CA2318080C - Wavelength-selective optical add/drop using tilting micro-mirrors - Google Patents
Wavelength-selective optical add/drop using tilting micro-mirrors Download PDFInfo
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- CA2318080C CA2318080C CA002318080A CA2318080A CA2318080C CA 2318080 C CA2318080 C CA 2318080C CA 002318080 A CA002318080 A CA 002318080A CA 2318080 A CA2318080 A CA 2318080A CA 2318080 C CA2318080 C CA 2318080C
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
- G02B6/29305—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating as bulk element, i.e. free space arrangement external to a light guide
- G02B6/2931—Diffractive element operating in reflection
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0201—Add-and-drop multiplexing
- H04J14/0202—Arrangements therefor
- H04J14/021—Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM]
- H04J14/0212—Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM] using optical switches or wavelength selective switches [WSS]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0005—Switch and router aspects
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0005—Switch and router aspects
- H04Q2011/0007—Construction
- H04Q2011/0022—Construction using fibre gratings
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0005—Switch and router aspects
- H04Q2011/0007—Construction
- H04Q2011/0026—Construction using free space propagation (e.g. lenses, mirrors)
Abstract
An optical switch particularly usable as a wavelength-division add/drop multiplexer (WADM) in a multi-wavelength communication system. Four multi-wavelength beams optically coupled to the input, output, add, and drop channels are arranged in parallel in a rectangular array and are incident upon a diffraction grating. The grating operating in one direction disperses the beams into their wavelength components and operating in the other direction recombines the wavelength components into a multi-wavelength beam. A lens focuses the components of the beams having a particular wavelength upon one of an array of tiltable micro-mirrors integrated on a silicon substrate. In one position, the mirror for a particular wavelength reflects that wavelength component from the input beam back to the output beam. In a second position, that mirror reflects that wavelength component from the input beam back to the drop beam and reflects that same wavelength component from the add beam back to the output beam. The same optics can be used for a second set of beams which are switched in synchronism with the first set. The array of mirrors can be fabricated to be tiltable to more than two positions so that the input beam can be selectively coupled to either the output beam or one of at least two drop beams while the ouput beam is correspondingly selectively coupled to either the input beam or one of at least two add beams.
Description
Wavelength-Selective Optical Add/Drop Using Tilting Micro-Mirrors FIELD OF THE INVENTION
The invention relates generally to optical communication systems. In particular, the invention relates to an optical add/drop.
BACKGROUND ART
Communication systems are being increasingly implemented on silica optical fibers that favorably transmit in optical bands around 1300nm and 1550nm. In older fiber transmission systems, an optical transmitter modulates a laser emitting in one of these two bands according to an electrical data signal. At the receiving end, an optical detector converts the modulated optical signal to an electrical signal corresponding to the originally impressed data signal. Typically, the capacity of such fiber transmission systems is limited by the opto-electronics at the two ends.
Systems having electronic data rates near 2.SGb/s are entering service, and systems at IOGb/s are being developed. Further significant increases in electronic speed are not anticipated for the near future.
More recent systems have nonetheless multiplied the data capacity of an optical fiber channel by means of wavelength-division multiplexing. The transmitting end includes multiple optical transmitters, each with its own laser, and the respective lasers have slightly different but well determined wavelengths. The separate optical carriers are modulated by respective data signals, and the multiple carriers are then combined (optically multiplexed) onto a single fiber.
At the receiving end, the process is reversed. An optical demultiplexer separates the WDM
signal into its wavelength-designated components. Separate detectors received the different components and provide separate electrical data signals. WDM systems are being fielded with four wavelengths, and even larger numbers of WDM channels may be feasible in the future.
What has been described to this point is a point-to-point WDM
telecommunications system in which all the optical signals are generated and transmitted from one point and are received and detected at another point. That is, opto-electronic conversion is required at each point of a network in which signals need to be switched into or aut of transmission path. Such opto-electronic circuitry is expensive.
The most frequent form of electrical multiplexing is time-division multiplexing, in which the transmitted signal is divided into a multiple time slots organized into blocks. One data signal is assigned one slot in each block, and the destination of that data signal may well differ from data signals in adjacent time slots. One of the most fundamental components of a multiplexed electrical communication network is an add/drop multiplexes (ADM). As illustrated in FIG. 1, an add/drop muftiplexer 10 receives a transport signal from an input fiber 12 and transmits the transport signal to an output fiber 14. Typically, most of the multiplexed signals pass through the add/drop multiplexes l0 from the input fiber 12 to the output fiber 14 with no change. However, the add/drop multiplexes I O has the capability to remove one or more of the multiplexed signals from the input fiber 12 and puts them on a drop line 16. Simultaneously, it puts replacement multiplexed signals from an add line 18 onto the output fiber 14.
.20 A wavelength-division add/drop multiplexes (WARM) is greatly desired for WDM
communication networks having more than two nodes between which data is transmitted and, usually, selectively switched to other nodes according to wavelength. It is possible to include complete optical-to-electrical-to-optical conversion at the WAI)M, but the expense is great. It is instead desired to use an all-optical WADM in which one or more wavelengths are selectively dropped and added at the node without the need to convert the optical signals on the fiber to electrical form.
Optical wavelength-selective ADMs have been fabricated by using available wavelength multiplexers and demultiplexers, such as conventional gratings or waveguide array gratings, to 3.18 PCT/US99/Ot620 demultiplex ali the wavelength channels onto individual fibers. using individual 2X2 switches on each single-wavelength fiber to configure it for pass through or add/drop, and then remultiplexing all the signals back onto a single fiber. However, the components used in this approach introduce large losses for the pass-through channels, and the 4 equipment is costly and bulky.
Ford et al. has disclosed a WADM utilizing a linear array of micro electromechanical (MEM) minors in "Wavelength-selectable add/drop with tilting'micromirrors,"
Postdeadline Papers, LEOS '97, IEEE Lasers and Electro-Optics Society 199'7 Annual Meeting, November 1997, San Francisco, California, pp. PD2.3, 2.4. A simplified and modified view of the optics 19 of Ford et al. is shown in the schematic diagram of FIG. 2. Two ports P,, Pi provide generally parallel but separated optical paths 20, 22 incident upon a grating 24, which wavelength separates the beams 20, 22 into their respective wavelength components. In the illustration, only two wavelengths are illustrated, the one wavelength by solid lines 20" 22, and the other by dashed lines 20z, 22=. Importantly, the beams of different wavelengths are angularly separated while those of the same wavelength remain substantially parallel. A
lens 25 focuses all the beams onto a micro-mirror array 26 comprising separately tiltable micro-mirrors 28" 28,. In the first position of the micro-mirrors 28" 282, illustrated by the solid lines, they reflect light input from the first port P, directly back to the first port P,. That is, in these first positions, the mirrors are perpendicular to the beams 20,, 202. However, in the second position, illustrated by dotted lines, the mirrors 28,, 282 reflect light received from the first port P, to the second port P,.
That is, in the second positions the first mirror 28, is perpendicular to the bisector of the beams 20" 22" and the second minor 28i is perpendicular to the bisector of the beams 20" 22z. In the second positions, the mirrors 28,, 282 also reflect light received from the second port P~ to the first port P,.
As mentioned, there may be additional mirrors 28 for additional WDM
wavelengths, and all the mirrors are separately controllable between their two positions. A
tilting angle for the mirrors 28 of about 7° is sufficient. The figure shows neither the collimating lenses associated with the two ports P,, P,, nor a quarter-wave plate disposed between the grating 24 and lens 25 to average out polarization effects of the grating 24, nor a folding mirror arranged in the beam for one of the ports.
Ford et al. incorporate their optics 19 into a wavelength-division add/drop multiplexer illustrated schematically in FIG. 3. The input fiber 12, the output fiber 14 and a bi-directional optical transport path 30 are connected to a first optical circulator 31 such that optical signals received from the input fiber 12 are routed to the bi-directional transport path 30 and signals received from the bi-directional transport path are routed to the autput fiber 14. The other end of the bi-directional transport path 30 is connected to the first port P, of the optics 19, and a bi-directional client path 32 is connected to the second port P, of the optics 19. The bi-directional client path 32, the optical add line 18 and the optical drop line 16 are connected to a second optical circulator 34 such that signals received from the add line 18 are routed to the bi-directional client path 32 and signals received from the bi-directional client path 32 are routed to the drop line 16.
Considering only one wavelength, if the micro-mirror 28, is set in its retroreflective first position, the multiplexed signal of that wavelength is routed from the input fiber 12 into the optics 19 through the first port P, and is reflected back out the same port P, to be thereafter routed to the output fiber 14. However, if the micro-mirror 28, is set in its transreflective second position, the multiplexed signal of that wavelength is instead reflected in a different direction and exits the optics 19 on the second port PZ, from where is it routed to the drop line I6.
Simultaneously, with the micro-minror 28, in its second position, a signal received from the add line 18 is routed by the second circulator 34 to the second port PZ of the optics 19 and is transreflected to the first port P,. The first circulator 31 then routes the added signal to the output fiber 14.
An interesting characteristic of the WADM structure of Ford et al. is the inability of the micro-mirrors 28 to retroreflect a signal input from the ADD line 18 through the second port P, back to the drop line 16. In fact, this is not a problem for an ADM, since an ADM is not usually designed for a connection between the add and the drop lines. However, the Ford device cannot be used as a 2X2 interconnect between two transport paths. An interconnect does require WO 99/383x8 PCT/US99/01620 transmission between the ports that Ford et al. label as the add and drop pons.
I have discovered that a good way to visualize the WADM of Ford et al. is shown in FIGS. 4A and 4B, which illustrate the angular arrangements of the beam incident on or reflected from one of the micro-mirrors in the micro-mirror array 26. The beams are shown passing through a spherical surface 40 centered on the first micro-mirror 28, and located between the micro-mirror array 26 and the lens 25. The same basic arrangement exists for all the micro-mirrors 28 so only a single wavelength-separated beam 20, 22 needs to be considered. To be precise, each beam 20, 22 represents an angular range of a comically shaped beam. Figures 4A
and 4B show the angular relationship between the beams 20, 22 and a normal 42 (represented by a cross) of the tilting mirror 28. In the first mirror position of F1G. 4A, the mirror normal 42 is~
coincident with the beam 20 from the first port P, to thereby reflect radiation received from that port directly back to that port. Whatever radiation the mirror 28 receives from the second beam 22 from the second port PZ is reflected to a spurious beam 44, marked by a dashed circle, which is lost from the system. This spurious reflection may be described as resulting from the mirror normal 42 acting as a symmetry direction for reflections of the beam 22. In the second mirror position of FIG. 4B, the mirror normal 42 falls between the two beams 20, 22.
That is, the normal is coincident with the bisector of the angle between the two beams 20, 22. As a result, the light that the mirror 28 receives from the first beam 20 through the first port P, is reflected along the second beam 22 to the second port PZ. Also, the light that the mirror 28 receives from the second beam 22 through the second port P2 is reflected along the first beam 20 to the first port P,. Both these reflections can be described in terms of the mirror normal 42 being a mirror point.
The combination of movable mirrors and a grating as shown by Ford et al. has many desirable characteristics and is able to independently add and drop at the ADM
any of a number of wavelengths on the transport fiber.
However, this design suffers at least two problems. It requires two circulators to separate signals going in opposite directions on the bi-directional paths 30, 32.
Circulators are expensive and add loss. In addition, the experimental results presented by Ford et al.
for a device with _5_ 200GHz channel spacings show very sharply peaked channel passbands, rather the desired flat-topped passbands.
A further problem shared by Ford et al. with many types of optical add/drop circuits is that the add and drop lines as well as the input and output lines are wavelength-division multiplexed. For the near future, a WADM represents a demarcation point between a multi-wavelength optical network for transport and an electronic network or digital switch for a client interface. Hence, a WARM having a multi-wavelength add and drop lines requires additional optical multiplexing and demultiplexing on the side of the client interface.
As the number of WDM wavelength channels increases, the losses associated with the splitters and combiners begin to significantly impact the system. Equipping the detectors of the receiver with wavelength filters adds to its cost and results in an inflexibility in wavelength assignment.
SUMMARY OF THE INVENTION
The invention may be summarized as an add/drop optical circuit in which four beam paths arranged in a two-dimensional array are incident upon a tiltable mirror.
In one position of the mirror, two of the beams on one side of the array are reflectively coupled. In the other position of the mirrors, respective pairs of beams at opposed diagonal comers of the array are reflectively coupled. The invention may be extended to a multiple-wavelength signal using a grating to complementarily disperse and combine the wavelength components.
The addldrop optical circuit is particularly useful in a wavelength-division multiplexed (WDM) fiber communications network for add/dropping of one or more wavelength channels at a node.
The invention can be further extended to a dual ADM proving synchronous switching of at least two sets of four beam paths, as is particularly useful for two-ring WDM networks in which a working and a protection fiber are synchronously switched at a network node.
2S Yet another extension of the invention includes an array of tiltable mirrors having three or more positions such that the input and output beams can be routed to one of multiple pairs of add and drop beams.
In another aspect of the invention applicable to many embodiments, the spurious coupling between multiple add and drop lines can be avoided by arranging the beams in a more irregular array.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is schematic illustration of the functions of an add/drop multiplexer.
FIG. 2 is a schematic illustration of the optics of a prior-art wavelength-division add/drop multiplexer (WADM).
FIG. 3 is a schematic illustration of the WARM of FIG. 2.
FIGS. 4A and 4B are schematic illustrations of the relationship between the mirror angle and the beams in the WADM of FIG. 3.
FIG. 5 is a schematic isometric representation of the wavelength-division add/drop multiplexer.
FIGS. 6A and 6B are schematic illustrations of the angular relationships between the four beams of the WADM of FIG. 5 and one of the micro-mirrors in its two tilting positions.
FIG. 7 is a schematic illustration of the angular relations between the four beams and the micro-mirror in a generalized arrangement of the beams.
FIGS. 8A and 8B are schematic illustrations of the angular relationships between the eight beams of a dual WADM and one of the micro-mirrors in its two tilting positions.
FiG. 9 is a schematic representation of the three positions of tiltable mirror providing the ability to selectively couple input and output beams to more than one set of add and drop lines.
FIGS. 10A, l OB, and l OC show the angular arrangements of the beams and mirror normal for the embodiment of FIG. 9.
FIG. 11 shows the extension of the embodiment of FIGS. 9 and l0A through l OB
to separated input and output beams and separated add and drop beams.
2~ FIG. 12 illustrates the arrangement of beams and mirror normals for a large number of add and drop beams.
FIG. 13 illustrates an improvement on the arrangement of FIG. 13 that eliminates _7_ spurious coupling between add and drop beams.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The wavelength-division add/drop multiplexes (WADM) of Ford et al. uses two bi-directional beam paths with respective ports to from its optics section.
Necessarily, the two beam paths are arranged in a linear array. I propose, as illustrated in the isometric view of FIG. 5, the use of four parallel, directional, input and output beam paths 50, 52, 54, 56 arranged in a two-dimensional array. The four beams in this arrangement are the input beam 50, the output beam 52, the add beam 54, and the drop beam 56, the input and add beams 50, 54 propagating oppositely from the output and drop beams 52, 56. The four beams are incident on the diffraction grating 24, which wavelength separates the beams into the same wavelength-dispersed pattern. It is noted that the diffraction grating diffractively separates the incident beams 50, 54 into their wavelength component, and ii also diffractively combines the respective wavelength components into the exiting beariis 52, 56. In the linear reciprocal system of FIG. 5, the four beams S0, 52, 54, 56 wil! be similarly explained as though they were propagating in a single direction. The illustration of FIG. S does not show the lenses at the exterior ends of the four beams which substantially collimate those beams so that resolution of the diffraction grating is increased. Also not shown are the fibers coupled to the beams and possibly folding mirrors to reduce the overall size of the system.
The grating 24 diffracts each of the four beams 50, 52, 54, 56 into their respective wavelength components towards the lens 25, which focuses the different wavelength components towards the respective micro-mirrors 28,, 28z. Only two micro-mirrors 28 are illustrated here.
For an N wavelength WDM system, N micro-mirrors 28 are required. The micro-mirror 28 for each wavelength has two positions. The technology for fabricating such mirrors is disclosed by:
(1) Lornbeck in "Defonnable-minor spatial-light modulators," Proceedings ojrhe SPIE, vol. 1150, August 1989, pp. 86-102; (2) Boysel et al. in ''Integration of deformable mirror devices with optical filters and waveguides," Proceedings ojthe SPIE, vol.
1793, Integrated Optics and Microstructures, 1992, pp. 34-39; and (3) Peterson, "Micromechanical light _g_ modulator array fabricated on silicon," Applied Physics Letters, vol. 3 l, 1977, p. X21. Foundry service and design information are available from the MEMS Technology Application Center.
MCNC, Research Triangle Park, North Carolina. The information is available on the Internet at http://www.mcnc.org/mumps.html.
The following discussion with respect to the mirror reflections will refer to the beams ~0, 52, 54, 56 prior to the grating 24, but it is understood that the corresponding wavelength-separated beam is intended. In the first position, the micro-mirror 28 reflects the light it receives from the input beam SO to the output beam 52. In the second position, the micro-mirror 28 reflects the light it receives from the input beam 50 to the drop beam 56 and reflects the light it receives from the add beam 54 to the output beam 52.
The wavelength-components of any beam reflected from the mirrors 28,, 28, are collimated by the lens 25, and the diffraction grating 24 recombines them into the output beam 52 and drop beam 56. The beams 50, 52, 54, 56 directly correspond to the four ports of the desired wavelength-division add/drop multiplcxer. No circulators are required.
The angular distributions of the beams at the micro-mirror 28 are illustrated by FIGS. 6A
and 6B. In the first position illustrated in FIG. 6A, the mirror normal 42 is directed midway between the input and output beams 50, 52. That is, the mirror normal 42 is coincident with the bisector of the angle between the input and output beams 50, 52. In this position, the input beam 50 is reflected to the output beam 52. Also in this position, the add beam 54 is reflected to a spurious drop beam 60, and the drop beam is reflected to a spurious add beam 62. In an ADM, these spuriotu beams 60, 62 are only a nuisance to be absorbed if necessary.
In the second position, the mirror normal 42 is located midway between the output beam 52 and the add beam 54 and also midway between the input beam 50 and the drop beam 56, thereby reflecting the input beam 50 to the drop beam and reflecting the add beam 54 to the output beam 52.
The beams illustrated in FIGS. 6A and 6B have been arranged in a square configuration.
However, it is also possible to arranged them in a rectangular configuration.
Indeed, the beams ~0, ~2, 54, 56 may be arranged in a parallelepiped arrangement illustrated in FIG. 7. A
parallelepiped is a quadrilateral figure having two pair of opposed sides.
Within a pair, the _g-opposed sides are parallel and of equal length, but there is no additional resuiction between the pairs. For an add/drop, the input and drop beams have to be on the opposed corners of the parallelepiped, and the add and output beams have to be on the other opposed corners. The first position 42, is located between the input and output beams 50, 52, and the second position 42, is located at the midpoint between input and drop beams 50, ~6, which is also the midpoint between the add and output beams 54, 52. Strictly speaking, the above description of rectangular and parallelepipedal arrangements is not completely accurate in the space between the lens 25 and the micro-mirror array 26 since these planar features are being mapped onto a spherical surface 40. The description in terms of angular arcs passing through the mirror norms! in its two positions is more acctuate.
This invention is not limited to a single add/drop but may extended to multiple add/drops.
A dual add/drop is the most immediately useful. and is applicable to dual-ring communication networks. In a dual-ring network, two fibers run in parallel around a ring, and signals propagate in anti-parallel directions on the two ring. In the simplest cxample, the first fiber serves as a 1 S protection fiber for the primary working fiber. Even if both fibers are cut at the same point in the ring, traffic can be rerouted to all nodes on the ring. The dual add/drop includes a similar adding and dropping function synchronously performed on both fibers.
The beams for the first ring fiber will be labeled by 50-l, 52-1, 54-1, 56-1 in correspondence to the labeling of FIGS. 5 through 7; those for the second ring fiber, by 50-2, 52-2, 54-2, 56-2. The beads external to the dual add/drop are arranged in a 2X8 array with the beams for the second fiber arranged outside those for the first ring fiber with all the input and output beams arranged along one long side of the array and all the add and drop beams arranged along the other long side. All eight beams use the same grating ~'.4, lens 25, and micro-minor array 26, as in FIG. 5.
The angular distributions of the beams at a micro-mirror for a dual add/drop are illustrated in FIGS. 8A and 8B. The positions of the mirror normal 42 with respect to the beams 50-1, ~2-1, ~4-l, 56-1 of the first ring fiber are the same as for the system of FIGS. ~, 6A, and 6B, whether in the first or the second position of the mirror. In the first position of FIG. 7A, the - l 0-mirror 28 reflects the first input beam ~0-1 to the first output beam ~2-2 and simultaneously reflects the second input beam SO-2 to the second output beam ~2-2. In the second position of FIG. 7B, the mirror reflects the first add beam 54-1 to the first output beam 52-1 and reflects the first input beam SO-1 to the first drop beam 56-1. Simultaneously, it reflects the second add beam 54-2 to the second output beam 52-2 and reflects the second input beam 50-2 to the second drop beam 56-2. There is no inherent mixing of the signals associated with the first and second ring fibers. Obviously, the dual add/drop provides substantial savings over two single add/drops.
For the dual add/drop, the arrangement of the beams may vary somewhat between the first and second ring fiber. The replication of beams can be extended to further ring fibers or the like, but the optics become increasingly difficult.
The preceding embodiments have relied upon arrays of tiltable mirrors having two positions providing a selection of passing through the input beam to the output beam or of coupling the input and output beams respectively to a single set of drop and add beams. As mentioned previously, it is desirable to provide multiple sets of drop and add beams for the client interface. This can be accomplished by the use of tiltable mirrors having three or more positions.
A first embodiment of a mufti-add/drop ADM illustrated in FIG. 9 follows the apparatus of Ford et al., which is illustrated in FIGS. 2 and 3. For each micro-mirror 28 in the micro-minor array 26, there is one central input/output beam 20 bracketed by two add/drop beams 22-1, 22-2.
The input/output beam 20, after collimation by the lens 25 and wavelength dispersion by the grating 24 is associated with the first port P, of the switching optics 19 while the two add/drop beams 22-1, 22-2 are respectively associated with two second ports PZ." Pz.z, each having its own circulator 34 and input and output lines 16, 18.
In this embodiment, the micro-mirror 28 has three possible positions. In a first position 70, its normal is coincident with the inputJoutput beam 20 so as to retroreflect the input to the output. In a second position 72, its normal is coincident with the angular bisector of the inputJoutput beam 20 and the first add/drop beam 22-1 so as to transreflect signals between those two beams. In a third position 74, its normal is coincident with the angular bisector of the input/output beam 20 and the second add/drop beam 22-2 so as to transreflect signals between -l l-these two beams.
The angular relationships between the beams in the various positions are illustrated in FIGS. 10A, IOB, and IOC. In the first mirror position 70 illustrated in FIG.
10A. the mirror normal 42 is incident with the input/output beam 20 so as to retroreflect any light. In this position, however, the two drop/add beams 22-1, 22-2 are reflectively coupled.
This is generally not a desired coupling, and the management of the add/drop net<vork element should be designed to prevent either the transmission or reception of such coupled signals. In the second minor position 72 illustrated in FIG. IOB, the mirror normal 42 is directed midway between the input/output beam 20 and the first add/drop beam 22-1 so as to reflectively couple them. As a result, the input beam is coupled to the first drop beam, and the first add beam is coupled to the output beam. This configuration also couples the second add/drop beam 22-2 to an undesired spurious beam.44, which may require special absorption of the spurious beam 44. Similarly, in the third mirror position 74, illustrated in FIG. 1 OC, the mirror normal 42 is directed to between the input/output beam 20 and the second add/drop beam 22-2 to thereby reflectively coupled those two beams 20, 22-2. Again disadvantageously, the first add/drop beam 22-1 is reflectively coupled to a spurious beam 44.
The extension of the dual add/drop ports to the embodiment of FIG. 5 is straightforward, as illustrated in FIG. 1 I for the relative angular orientations of the six beams and the mirror normais. There is one input beam S0, one output beam 52, a first and a second add beam 54-1, 54-2, and a first and a second drop beam 56-1, 56-2. These beams are arranged in a rectangular 2x3 array, but the array may be in the form of a parallelepiped. The mirror normal 44 may have three positions, the first position between the input and output beams ~0, 52, the second position at the central bisector of the input and output beams S0, 52 and the first add and drop beams 54-1, 56-1, and the third position at the central bisector of the input and output beams 50, 52 and the second add and drop beams 54-2, 56-2. These six beams are optically coupled to six fibers or other optical paths at the exterior of the WADM.
The extension of FIGS. 9, l0A-l OC, and 11 can be extended to yet more positions of the tiltable mirrors and more than two sets of add/drop lines. A beam configuration for a multiple add/drop for an ADM is illustrated in FIG. 12. The add and drop beams 50, 52 are arranged in a 2x7 regular rectangular array with first through sixth add beams ~4-1 through 54-6 and first through six drop beams 56-1 through ~6-6. The tiltable minor 28 can assume any of seven positions indicated by the mirror normals 42 illustrated in the figure. In the first position, with the minor normal between the input and output beams 50, 52, those two beams are reflectively coupled. In each of the remaining six positions, the input beam SO is reflectively coupled to a selected one of the six drop beams 56-1 through 56-6 while the output beam 52 is reflectively coupled to a corresponding one of the six add beams 54-1 through 54-6. The position of the input and output beams 50, 52 within the 2x7 array is fairly arbitrary as long as they are vertically paired.
The configurations of FIGS. I OA, 11, and 12 produce undesirable coupling between different ones of the drop and add lines. Although the coupling can be avoided through a systems approach of inactivating the so coupled lines, another solution rests on the fact that the undesired couplings arise from the regular arrangement of all the beams. One example of the angular beam arrangement for six add and drop beams which are not extraneously coupled is illustrated in FIG. 13. The six add beams 54-1 through 54-6 and the six drop beams 56-1 through 56-6 are arranged in a regular rectangular 2x6 array with the vertical spacings being at least two beam widths at the diffraction grating and at the parallel beams external to the WDM. The add and drop beams 50, 52 are positioned with respect to this add/drap array but are spaced from them by a vertical spacing other than an even multiple of add/drap vertical spacing. As an example, let the input and output beams be vertically located at a height of 0, let the first drop and add beams 54-1, 56-2 be located at a height of 3, and let the vertical add/drop spacings be 2, all the distances being in arbitrary or normalized units.
The micro-mirror can assume any of seven positions. In the first position, the mirror 2~ normal 42 falls at a height of 0 between the input and output beams 50, 52 and reflectively couple them. In the second position, the mirror normal 42 falls at a height of 1'/~ so that the mirror 28 couples the input beam to the first drop beam 56-1 and couples the output beam 52 to the first add beam 54-1. The remaining positions of the mirror normal 42 fall at 2'/~, 3 '/~, 4'/Z, and 5%. In no case is an add beam 54 reflectively coupled to a drop beam 56.
Spurious beams 44 do fall within the area of the array, as indicated by dotted circles, but the spurious beams 44 are located between the add and drop beams 54, 56. Other irregular arrangement of beams is possible, as is now apparent to the ordinary artisan. In particular', in the three-beam arrangement of FIGS. 9 and l0A through lOC and in the six-beam arrangement of FIG. 11, spurious add/drop coupling can be eliminated by different vertical spacings between the middle and top beams than between the middle and bottom beams.
Although a conventional reflective diffraction grating has been shown, other wavelength dispersive media may be used, such as a transmissive diffraction grating or a hologram that additionally includes focusing functions.
The invention thus provides an compact and economical optical add/drop circuitry, and one providing flexibility in its design.
The invention relates generally to optical communication systems. In particular, the invention relates to an optical add/drop.
BACKGROUND ART
Communication systems are being increasingly implemented on silica optical fibers that favorably transmit in optical bands around 1300nm and 1550nm. In older fiber transmission systems, an optical transmitter modulates a laser emitting in one of these two bands according to an electrical data signal. At the receiving end, an optical detector converts the modulated optical signal to an electrical signal corresponding to the originally impressed data signal. Typically, the capacity of such fiber transmission systems is limited by the opto-electronics at the two ends.
Systems having electronic data rates near 2.SGb/s are entering service, and systems at IOGb/s are being developed. Further significant increases in electronic speed are not anticipated for the near future.
More recent systems have nonetheless multiplied the data capacity of an optical fiber channel by means of wavelength-division multiplexing. The transmitting end includes multiple optical transmitters, each with its own laser, and the respective lasers have slightly different but well determined wavelengths. The separate optical carriers are modulated by respective data signals, and the multiple carriers are then combined (optically multiplexed) onto a single fiber.
At the receiving end, the process is reversed. An optical demultiplexer separates the WDM
signal into its wavelength-designated components. Separate detectors received the different components and provide separate electrical data signals. WDM systems are being fielded with four wavelengths, and even larger numbers of WDM channels may be feasible in the future.
What has been described to this point is a point-to-point WDM
telecommunications system in which all the optical signals are generated and transmitted from one point and are received and detected at another point. That is, opto-electronic conversion is required at each point of a network in which signals need to be switched into or aut of transmission path. Such opto-electronic circuitry is expensive.
The most frequent form of electrical multiplexing is time-division multiplexing, in which the transmitted signal is divided into a multiple time slots organized into blocks. One data signal is assigned one slot in each block, and the destination of that data signal may well differ from data signals in adjacent time slots. One of the most fundamental components of a multiplexed electrical communication network is an add/drop multiplexes (ADM). As illustrated in FIG. 1, an add/drop muftiplexer 10 receives a transport signal from an input fiber 12 and transmits the transport signal to an output fiber 14. Typically, most of the multiplexed signals pass through the add/drop multiplexes l0 from the input fiber 12 to the output fiber 14 with no change. However, the add/drop multiplexes I O has the capability to remove one or more of the multiplexed signals from the input fiber 12 and puts them on a drop line 16. Simultaneously, it puts replacement multiplexed signals from an add line 18 onto the output fiber 14.
.20 A wavelength-division add/drop multiplexes (WARM) is greatly desired for WDM
communication networks having more than two nodes between which data is transmitted and, usually, selectively switched to other nodes according to wavelength. It is possible to include complete optical-to-electrical-to-optical conversion at the WAI)M, but the expense is great. It is instead desired to use an all-optical WADM in which one or more wavelengths are selectively dropped and added at the node without the need to convert the optical signals on the fiber to electrical form.
Optical wavelength-selective ADMs have been fabricated by using available wavelength multiplexers and demultiplexers, such as conventional gratings or waveguide array gratings, to 3.18 PCT/US99/Ot620 demultiplex ali the wavelength channels onto individual fibers. using individual 2X2 switches on each single-wavelength fiber to configure it for pass through or add/drop, and then remultiplexing all the signals back onto a single fiber. However, the components used in this approach introduce large losses for the pass-through channels, and the 4 equipment is costly and bulky.
Ford et al. has disclosed a WADM utilizing a linear array of micro electromechanical (MEM) minors in "Wavelength-selectable add/drop with tilting'micromirrors,"
Postdeadline Papers, LEOS '97, IEEE Lasers and Electro-Optics Society 199'7 Annual Meeting, November 1997, San Francisco, California, pp. PD2.3, 2.4. A simplified and modified view of the optics 19 of Ford et al. is shown in the schematic diagram of FIG. 2. Two ports P,, Pi provide generally parallel but separated optical paths 20, 22 incident upon a grating 24, which wavelength separates the beams 20, 22 into their respective wavelength components. In the illustration, only two wavelengths are illustrated, the one wavelength by solid lines 20" 22, and the other by dashed lines 20z, 22=. Importantly, the beams of different wavelengths are angularly separated while those of the same wavelength remain substantially parallel. A
lens 25 focuses all the beams onto a micro-mirror array 26 comprising separately tiltable micro-mirrors 28" 28,. In the first position of the micro-mirrors 28" 282, illustrated by the solid lines, they reflect light input from the first port P, directly back to the first port P,. That is, in these first positions, the mirrors are perpendicular to the beams 20,, 202. However, in the second position, illustrated by dotted lines, the mirrors 28,, 282 reflect light received from the first port P, to the second port P,.
That is, in the second positions the first mirror 28, is perpendicular to the bisector of the beams 20" 22" and the second minor 28i is perpendicular to the bisector of the beams 20" 22z. In the second positions, the mirrors 28,, 282 also reflect light received from the second port P~ to the first port P,.
As mentioned, there may be additional mirrors 28 for additional WDM
wavelengths, and all the mirrors are separately controllable between their two positions. A
tilting angle for the mirrors 28 of about 7° is sufficient. The figure shows neither the collimating lenses associated with the two ports P,, P,, nor a quarter-wave plate disposed between the grating 24 and lens 25 to average out polarization effects of the grating 24, nor a folding mirror arranged in the beam for one of the ports.
Ford et al. incorporate their optics 19 into a wavelength-division add/drop multiplexer illustrated schematically in FIG. 3. The input fiber 12, the output fiber 14 and a bi-directional optical transport path 30 are connected to a first optical circulator 31 such that optical signals received from the input fiber 12 are routed to the bi-directional transport path 30 and signals received from the bi-directional transport path are routed to the autput fiber 14. The other end of the bi-directional transport path 30 is connected to the first port P, of the optics 19, and a bi-directional client path 32 is connected to the second port P, of the optics 19. The bi-directional client path 32, the optical add line 18 and the optical drop line 16 are connected to a second optical circulator 34 such that signals received from the add line 18 are routed to the bi-directional client path 32 and signals received from the bi-directional client path 32 are routed to the drop line 16.
Considering only one wavelength, if the micro-mirror 28, is set in its retroreflective first position, the multiplexed signal of that wavelength is routed from the input fiber 12 into the optics 19 through the first port P, and is reflected back out the same port P, to be thereafter routed to the output fiber 14. However, if the micro-mirror 28, is set in its transreflective second position, the multiplexed signal of that wavelength is instead reflected in a different direction and exits the optics 19 on the second port PZ, from where is it routed to the drop line I6.
Simultaneously, with the micro-minror 28, in its second position, a signal received from the add line 18 is routed by the second circulator 34 to the second port PZ of the optics 19 and is transreflected to the first port P,. The first circulator 31 then routes the added signal to the output fiber 14.
An interesting characteristic of the WADM structure of Ford et al. is the inability of the micro-mirrors 28 to retroreflect a signal input from the ADD line 18 through the second port P, back to the drop line 16. In fact, this is not a problem for an ADM, since an ADM is not usually designed for a connection between the add and the drop lines. However, the Ford device cannot be used as a 2X2 interconnect between two transport paths. An interconnect does require WO 99/383x8 PCT/US99/01620 transmission between the ports that Ford et al. label as the add and drop pons.
I have discovered that a good way to visualize the WADM of Ford et al. is shown in FIGS. 4A and 4B, which illustrate the angular arrangements of the beam incident on or reflected from one of the micro-mirrors in the micro-mirror array 26. The beams are shown passing through a spherical surface 40 centered on the first micro-mirror 28, and located between the micro-mirror array 26 and the lens 25. The same basic arrangement exists for all the micro-mirrors 28 so only a single wavelength-separated beam 20, 22 needs to be considered. To be precise, each beam 20, 22 represents an angular range of a comically shaped beam. Figures 4A
and 4B show the angular relationship between the beams 20, 22 and a normal 42 (represented by a cross) of the tilting mirror 28. In the first mirror position of F1G. 4A, the mirror normal 42 is~
coincident with the beam 20 from the first port P, to thereby reflect radiation received from that port directly back to that port. Whatever radiation the mirror 28 receives from the second beam 22 from the second port PZ is reflected to a spurious beam 44, marked by a dashed circle, which is lost from the system. This spurious reflection may be described as resulting from the mirror normal 42 acting as a symmetry direction for reflections of the beam 22. In the second mirror position of FIG. 4B, the mirror normal 42 falls between the two beams 20, 22.
That is, the normal is coincident with the bisector of the angle between the two beams 20, 22. As a result, the light that the mirror 28 receives from the first beam 20 through the first port P, is reflected along the second beam 22 to the second port PZ. Also, the light that the mirror 28 receives from the second beam 22 through the second port P2 is reflected along the first beam 20 to the first port P,. Both these reflections can be described in terms of the mirror normal 42 being a mirror point.
The combination of movable mirrors and a grating as shown by Ford et al. has many desirable characteristics and is able to independently add and drop at the ADM
any of a number of wavelengths on the transport fiber.
However, this design suffers at least two problems. It requires two circulators to separate signals going in opposite directions on the bi-directional paths 30, 32.
Circulators are expensive and add loss. In addition, the experimental results presented by Ford et al.
for a device with _5_ 200GHz channel spacings show very sharply peaked channel passbands, rather the desired flat-topped passbands.
A further problem shared by Ford et al. with many types of optical add/drop circuits is that the add and drop lines as well as the input and output lines are wavelength-division multiplexed. For the near future, a WADM represents a demarcation point between a multi-wavelength optical network for transport and an electronic network or digital switch for a client interface. Hence, a WARM having a multi-wavelength add and drop lines requires additional optical multiplexing and demultiplexing on the side of the client interface.
As the number of WDM wavelength channels increases, the losses associated with the splitters and combiners begin to significantly impact the system. Equipping the detectors of the receiver with wavelength filters adds to its cost and results in an inflexibility in wavelength assignment.
SUMMARY OF THE INVENTION
The invention may be summarized as an add/drop optical circuit in which four beam paths arranged in a two-dimensional array are incident upon a tiltable mirror.
In one position of the mirror, two of the beams on one side of the array are reflectively coupled. In the other position of the mirrors, respective pairs of beams at opposed diagonal comers of the array are reflectively coupled. The invention may be extended to a multiple-wavelength signal using a grating to complementarily disperse and combine the wavelength components.
The addldrop optical circuit is particularly useful in a wavelength-division multiplexed (WDM) fiber communications network for add/dropping of one or more wavelength channels at a node.
The invention can be further extended to a dual ADM proving synchronous switching of at least two sets of four beam paths, as is particularly useful for two-ring WDM networks in which a working and a protection fiber are synchronously switched at a network node.
2S Yet another extension of the invention includes an array of tiltable mirrors having three or more positions such that the input and output beams can be routed to one of multiple pairs of add and drop beams.
In another aspect of the invention applicable to many embodiments, the spurious coupling between multiple add and drop lines can be avoided by arranging the beams in a more irregular array.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is schematic illustration of the functions of an add/drop multiplexer.
FIG. 2 is a schematic illustration of the optics of a prior-art wavelength-division add/drop multiplexer (WADM).
FIG. 3 is a schematic illustration of the WARM of FIG. 2.
FIGS. 4A and 4B are schematic illustrations of the relationship between the mirror angle and the beams in the WADM of FIG. 3.
FIG. 5 is a schematic isometric representation of the wavelength-division add/drop multiplexer.
FIGS. 6A and 6B are schematic illustrations of the angular relationships between the four beams of the WADM of FIG. 5 and one of the micro-mirrors in its two tilting positions.
FIG. 7 is a schematic illustration of the angular relations between the four beams and the micro-mirror in a generalized arrangement of the beams.
FIGS. 8A and 8B are schematic illustrations of the angular relationships between the eight beams of a dual WADM and one of the micro-mirrors in its two tilting positions.
FiG. 9 is a schematic representation of the three positions of tiltable mirror providing the ability to selectively couple input and output beams to more than one set of add and drop lines.
FIGS. 10A, l OB, and l OC show the angular arrangements of the beams and mirror normal for the embodiment of FIG. 9.
FIG. 11 shows the extension of the embodiment of FIGS. 9 and l0A through l OB
to separated input and output beams and separated add and drop beams.
2~ FIG. 12 illustrates the arrangement of beams and mirror normals for a large number of add and drop beams.
FIG. 13 illustrates an improvement on the arrangement of FIG. 13 that eliminates _7_ spurious coupling between add and drop beams.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The wavelength-division add/drop multiplexes (WADM) of Ford et al. uses two bi-directional beam paths with respective ports to from its optics section.
Necessarily, the two beam paths are arranged in a linear array. I propose, as illustrated in the isometric view of FIG. 5, the use of four parallel, directional, input and output beam paths 50, 52, 54, 56 arranged in a two-dimensional array. The four beams in this arrangement are the input beam 50, the output beam 52, the add beam 54, and the drop beam 56, the input and add beams 50, 54 propagating oppositely from the output and drop beams 52, 56. The four beams are incident on the diffraction grating 24, which wavelength separates the beams into the same wavelength-dispersed pattern. It is noted that the diffraction grating diffractively separates the incident beams 50, 54 into their wavelength component, and ii also diffractively combines the respective wavelength components into the exiting beariis 52, 56. In the linear reciprocal system of FIG. 5, the four beams S0, 52, 54, 56 wil! be similarly explained as though they were propagating in a single direction. The illustration of FIG. S does not show the lenses at the exterior ends of the four beams which substantially collimate those beams so that resolution of the diffraction grating is increased. Also not shown are the fibers coupled to the beams and possibly folding mirrors to reduce the overall size of the system.
The grating 24 diffracts each of the four beams 50, 52, 54, 56 into their respective wavelength components towards the lens 25, which focuses the different wavelength components towards the respective micro-mirrors 28,, 28z. Only two micro-mirrors 28 are illustrated here.
For an N wavelength WDM system, N micro-mirrors 28 are required. The micro-mirror 28 for each wavelength has two positions. The technology for fabricating such mirrors is disclosed by:
(1) Lornbeck in "Defonnable-minor spatial-light modulators," Proceedings ojrhe SPIE, vol. 1150, August 1989, pp. 86-102; (2) Boysel et al. in ''Integration of deformable mirror devices with optical filters and waveguides," Proceedings ojthe SPIE, vol.
1793, Integrated Optics and Microstructures, 1992, pp. 34-39; and (3) Peterson, "Micromechanical light _g_ modulator array fabricated on silicon," Applied Physics Letters, vol. 3 l, 1977, p. X21. Foundry service and design information are available from the MEMS Technology Application Center.
MCNC, Research Triangle Park, North Carolina. The information is available on the Internet at http://www.mcnc.org/mumps.html.
The following discussion with respect to the mirror reflections will refer to the beams ~0, 52, 54, 56 prior to the grating 24, but it is understood that the corresponding wavelength-separated beam is intended. In the first position, the micro-mirror 28 reflects the light it receives from the input beam SO to the output beam 52. In the second position, the micro-mirror 28 reflects the light it receives from the input beam 50 to the drop beam 56 and reflects the light it receives from the add beam 54 to the output beam 52.
The wavelength-components of any beam reflected from the mirrors 28,, 28, are collimated by the lens 25, and the diffraction grating 24 recombines them into the output beam 52 and drop beam 56. The beams 50, 52, 54, 56 directly correspond to the four ports of the desired wavelength-division add/drop multiplcxer. No circulators are required.
The angular distributions of the beams at the micro-mirror 28 are illustrated by FIGS. 6A
and 6B. In the first position illustrated in FIG. 6A, the mirror normal 42 is directed midway between the input and output beams 50, 52. That is, the mirror normal 42 is coincident with the bisector of the angle between the input and output beams 50, 52. In this position, the input beam 50 is reflected to the output beam 52. Also in this position, the add beam 54 is reflected to a spurious drop beam 60, and the drop beam is reflected to a spurious add beam 62. In an ADM, these spuriotu beams 60, 62 are only a nuisance to be absorbed if necessary.
In the second position, the mirror normal 42 is located midway between the output beam 52 and the add beam 54 and also midway between the input beam 50 and the drop beam 56, thereby reflecting the input beam 50 to the drop beam and reflecting the add beam 54 to the output beam 52.
The beams illustrated in FIGS. 6A and 6B have been arranged in a square configuration.
However, it is also possible to arranged them in a rectangular configuration.
Indeed, the beams ~0, ~2, 54, 56 may be arranged in a parallelepiped arrangement illustrated in FIG. 7. A
parallelepiped is a quadrilateral figure having two pair of opposed sides.
Within a pair, the _g-opposed sides are parallel and of equal length, but there is no additional resuiction between the pairs. For an add/drop, the input and drop beams have to be on the opposed corners of the parallelepiped, and the add and output beams have to be on the other opposed corners. The first position 42, is located between the input and output beams 50, 52, and the second position 42, is located at the midpoint between input and drop beams 50, ~6, which is also the midpoint between the add and output beams 54, 52. Strictly speaking, the above description of rectangular and parallelepipedal arrangements is not completely accurate in the space between the lens 25 and the micro-mirror array 26 since these planar features are being mapped onto a spherical surface 40. The description in terms of angular arcs passing through the mirror norms! in its two positions is more acctuate.
This invention is not limited to a single add/drop but may extended to multiple add/drops.
A dual add/drop is the most immediately useful. and is applicable to dual-ring communication networks. In a dual-ring network, two fibers run in parallel around a ring, and signals propagate in anti-parallel directions on the two ring. In the simplest cxample, the first fiber serves as a 1 S protection fiber for the primary working fiber. Even if both fibers are cut at the same point in the ring, traffic can be rerouted to all nodes on the ring. The dual add/drop includes a similar adding and dropping function synchronously performed on both fibers.
The beams for the first ring fiber will be labeled by 50-l, 52-1, 54-1, 56-1 in correspondence to the labeling of FIGS. 5 through 7; those for the second ring fiber, by 50-2, 52-2, 54-2, 56-2. The beads external to the dual add/drop are arranged in a 2X8 array with the beams for the second fiber arranged outside those for the first ring fiber with all the input and output beams arranged along one long side of the array and all the add and drop beams arranged along the other long side. All eight beams use the same grating ~'.4, lens 25, and micro-minor array 26, as in FIG. 5.
The angular distributions of the beams at a micro-mirror for a dual add/drop are illustrated in FIGS. 8A and 8B. The positions of the mirror normal 42 with respect to the beams 50-1, ~2-1, ~4-l, 56-1 of the first ring fiber are the same as for the system of FIGS. ~, 6A, and 6B, whether in the first or the second position of the mirror. In the first position of FIG. 7A, the - l 0-mirror 28 reflects the first input beam ~0-1 to the first output beam ~2-2 and simultaneously reflects the second input beam SO-2 to the second output beam ~2-2. In the second position of FIG. 7B, the mirror reflects the first add beam 54-1 to the first output beam 52-1 and reflects the first input beam SO-1 to the first drop beam 56-1. Simultaneously, it reflects the second add beam 54-2 to the second output beam 52-2 and reflects the second input beam 50-2 to the second drop beam 56-2. There is no inherent mixing of the signals associated with the first and second ring fibers. Obviously, the dual add/drop provides substantial savings over two single add/drops.
For the dual add/drop, the arrangement of the beams may vary somewhat between the first and second ring fiber. The replication of beams can be extended to further ring fibers or the like, but the optics become increasingly difficult.
The preceding embodiments have relied upon arrays of tiltable mirrors having two positions providing a selection of passing through the input beam to the output beam or of coupling the input and output beams respectively to a single set of drop and add beams. As mentioned previously, it is desirable to provide multiple sets of drop and add beams for the client interface. This can be accomplished by the use of tiltable mirrors having three or more positions.
A first embodiment of a mufti-add/drop ADM illustrated in FIG. 9 follows the apparatus of Ford et al., which is illustrated in FIGS. 2 and 3. For each micro-mirror 28 in the micro-minor array 26, there is one central input/output beam 20 bracketed by two add/drop beams 22-1, 22-2.
The input/output beam 20, after collimation by the lens 25 and wavelength dispersion by the grating 24 is associated with the first port P, of the switching optics 19 while the two add/drop beams 22-1, 22-2 are respectively associated with two second ports PZ." Pz.z, each having its own circulator 34 and input and output lines 16, 18.
In this embodiment, the micro-mirror 28 has three possible positions. In a first position 70, its normal is coincident with the inputJoutput beam 20 so as to retroreflect the input to the output. In a second position 72, its normal is coincident with the angular bisector of the inputJoutput beam 20 and the first add/drop beam 22-1 so as to transreflect signals between those two beams. In a third position 74, its normal is coincident with the angular bisector of the input/output beam 20 and the second add/drop beam 22-2 so as to transreflect signals between -l l-these two beams.
The angular relationships between the beams in the various positions are illustrated in FIGS. 10A, IOB, and IOC. In the first mirror position 70 illustrated in FIG.
10A. the mirror normal 42 is incident with the input/output beam 20 so as to retroreflect any light. In this position, however, the two drop/add beams 22-1, 22-2 are reflectively coupled.
This is generally not a desired coupling, and the management of the add/drop net<vork element should be designed to prevent either the transmission or reception of such coupled signals. In the second minor position 72 illustrated in FIG. IOB, the mirror normal 42 is directed midway between the input/output beam 20 and the first add/drop beam 22-1 so as to reflectively couple them. As a result, the input beam is coupled to the first drop beam, and the first add beam is coupled to the output beam. This configuration also couples the second add/drop beam 22-2 to an undesired spurious beam.44, which may require special absorption of the spurious beam 44. Similarly, in the third mirror position 74, illustrated in FIG. 1 OC, the mirror normal 42 is directed to between the input/output beam 20 and the second add/drop beam 22-2 to thereby reflectively coupled those two beams 20, 22-2. Again disadvantageously, the first add/drop beam 22-1 is reflectively coupled to a spurious beam 44.
The extension of the dual add/drop ports to the embodiment of FIG. 5 is straightforward, as illustrated in FIG. 1 I for the relative angular orientations of the six beams and the mirror normais. There is one input beam S0, one output beam 52, a first and a second add beam 54-1, 54-2, and a first and a second drop beam 56-1, 56-2. These beams are arranged in a rectangular 2x3 array, but the array may be in the form of a parallelepiped. The mirror normal 44 may have three positions, the first position between the input and output beams ~0, 52, the second position at the central bisector of the input and output beams S0, 52 and the first add and drop beams 54-1, 56-1, and the third position at the central bisector of the input and output beams 50, 52 and the second add and drop beams 54-2, 56-2. These six beams are optically coupled to six fibers or other optical paths at the exterior of the WADM.
The extension of FIGS. 9, l0A-l OC, and 11 can be extended to yet more positions of the tiltable mirrors and more than two sets of add/drop lines. A beam configuration for a multiple add/drop for an ADM is illustrated in FIG. 12. The add and drop beams 50, 52 are arranged in a 2x7 regular rectangular array with first through sixth add beams ~4-1 through 54-6 and first through six drop beams 56-1 through ~6-6. The tiltable minor 28 can assume any of seven positions indicated by the mirror normals 42 illustrated in the figure. In the first position, with the minor normal between the input and output beams 50, 52, those two beams are reflectively coupled. In each of the remaining six positions, the input beam SO is reflectively coupled to a selected one of the six drop beams 56-1 through 56-6 while the output beam 52 is reflectively coupled to a corresponding one of the six add beams 54-1 through 54-6. The position of the input and output beams 50, 52 within the 2x7 array is fairly arbitrary as long as they are vertically paired.
The configurations of FIGS. I OA, 11, and 12 produce undesirable coupling between different ones of the drop and add lines. Although the coupling can be avoided through a systems approach of inactivating the so coupled lines, another solution rests on the fact that the undesired couplings arise from the regular arrangement of all the beams. One example of the angular beam arrangement for six add and drop beams which are not extraneously coupled is illustrated in FIG. 13. The six add beams 54-1 through 54-6 and the six drop beams 56-1 through 56-6 are arranged in a regular rectangular 2x6 array with the vertical spacings being at least two beam widths at the diffraction grating and at the parallel beams external to the WDM. The add and drop beams 50, 52 are positioned with respect to this add/drap array but are spaced from them by a vertical spacing other than an even multiple of add/drap vertical spacing. As an example, let the input and output beams be vertically located at a height of 0, let the first drop and add beams 54-1, 56-2 be located at a height of 3, and let the vertical add/drop spacings be 2, all the distances being in arbitrary or normalized units.
The micro-mirror can assume any of seven positions. In the first position, the mirror 2~ normal 42 falls at a height of 0 between the input and output beams 50, 52 and reflectively couple them. In the second position, the mirror normal 42 falls at a height of 1'/~ so that the mirror 28 couples the input beam to the first drop beam 56-1 and couples the output beam 52 to the first add beam 54-1. The remaining positions of the mirror normal 42 fall at 2'/~, 3 '/~, 4'/Z, and 5%. In no case is an add beam 54 reflectively coupled to a drop beam 56.
Spurious beams 44 do fall within the area of the array, as indicated by dotted circles, but the spurious beams 44 are located between the add and drop beams 54, 56. Other irregular arrangement of beams is possible, as is now apparent to the ordinary artisan. In particular', in the three-beam arrangement of FIGS. 9 and l0A through lOC and in the six-beam arrangement of FIG. 11, spurious add/drop coupling can be eliminated by different vertical spacings between the middle and top beams than between the middle and bottom beams.
Although a conventional reflective diffraction grating has been shown, other wavelength dispersive media may be used, such as a transmissive diffraction grating or a hologram that additionally includes focusing functions.
The invention thus provides an compact and economical optical add/drop circuitry, and one providing flexibility in its design.
Claims (15)
1. An optical switching system, comprising:
at least four optical beams;
a wavelength-dispersive medium dispersing wavelength components of said at least four optical beams incident thereupon into respective wavelength-dispersed sub-beams;
an array of tiltable mirrors having reflective surfaces angularly movable between a first position and a second position; and a lens focusing said sub-beams of a respective wavelength upon a respective one of said mirrors;
wherein a respective one of said mirrors:
in said first position, optically couples a first one to a second one of said respective sub-beams; and in said second position, optically couples said first one to a third one of said respective sub-beams and optically couples said second one to a fourth one of said respective sub-beams.
at least four optical beams;
a wavelength-dispersive medium dispersing wavelength components of said at least four optical beams incident thereupon into respective wavelength-dispersed sub-beams;
an array of tiltable mirrors having reflective surfaces angularly movable between a first position and a second position; and a lens focusing said sub-beams of a respective wavelength upon a respective one of said mirrors;
wherein a respective one of said mirrors:
in said first position, optically couples a first one to a second one of said respective sub-beams; and in said second position, optically couples said first one to a third one of said respective sub-beams and optically couples said second one to a fourth one of said respective sub-beams.
2. The switching system of Claim 1, wherein said at least four optical beams consists of four generally parallel optical beams arranged in a parallelepipedal arrangement.
3. The switching system of Claim 2, wherein said parallelepipedal arrangement is a rectangular arrangement.
4. The switching system of Claim 1, further comprising a mufti-wavelength optical communications network having a switching node, wherein of said four optical beams:
a first one corresponding to said first sub-beams is connected to an input port of said switching node;
a second one corresponding to said second sub-beams is connected to an output port of said switching node;
a third one corresponding to said third sub-beams is connected to a drop port of said switching node; and a fourth one corresponding to said fourth sub-beams is connected to an add port of said switching node.
a first one corresponding to said first sub-beams is connected to an input port of said switching node;
a second one corresponding to said second sub-beams is connected to an output port of said switching node;
a third one corresponding to said third sub-beams is connected to a drop port of said switching node; and a fourth one corresponding to said fourth sub-beams is connected to an add port of said switching node.
5. The switching system of Claim 1, wherein said at least four optical beams comprise eight optical beams.
6. The switching system of Claim 5, wherein said eight optical beams are arranged in a rectangular arrangement.
7. The switching system of Claim 5, further comprising a multi-wavelength optical communications network having two counter-rotating optical paths and a switching node connected to said two optical paths, wherein of said optical beams:
first and fifth ones corresponding to said first sub-beams are connected to respective input ports of said switching node connected respectively to said first and second optical paths;
second and sixth ones corresponding to said second sub-beams are connected to respective output ports of said switching node connected respectively to said first and, second optical paths;
third and seventh ones corresponding to said third sub-beams are connected to respective drop ports of said switching node connected respectively to said first and second optical paths;
and fourth and eighth ones corresponding to said fourth sub-beams are connected to respective add ports of said switching node connected respectively to said first and second optical paths.
first and fifth ones corresponding to said first sub-beams are connected to respective input ports of said switching node connected respectively to said first and second optical paths;
second and sixth ones corresponding to said second sub-beams are connected to respective output ports of said switching node connected respectively to said first and, second optical paths;
third and seventh ones corresponding to said third sub-beams are connected to respective drop ports of said switching node connected respectively to said first and second optical paths;
and fourth and eighth ones corresponding to said fourth sub-beams are connected to respective add ports of said switching node connected respectively to said first and second optical paths.
8. The switching system of Claim 1, wherein said at least four optical beams comprise six optical beams;
wherein said mirrors in said array are angularly movable between said first position, said second position, and a third position; and wherein said respective one of said mirrors in said third position optically couples said first one to a fifth one of said respective sub-beams and optically couples said second one to a sixth one of said respective sub-beams.
wherein said mirrors in said array are angularly movable between said first position, said second position, and a third position; and wherein said respective one of said mirrors in said third position optically couples said first one to a fifth one of said respective sub-beams and optically couples said second one to a sixth one of said respective sub-beams.
9. The switching system of Claim 8, wherein said six beams are arranged in two linearly arranged triplets, spacings between said beams in each of said triplets being non-equal.
10. The switching system of Claim 1, wherein said mirrors are integrated in a silicon substrate.
11. An optical switching system, comprising:
three optical beams;
a wavelength-dispersive medium dispersing wavelength components of said three optical beams incident thereupon into respective wavelength-dispersed sub-beams;
an array of tiltable mirrors having reflective surfaces angularly movable between a first position, a second position, and a third position; and a lens focusing said sub-beams of a respective wavelength upon a respective one of said mirrors;
wherein a respective one of said mirrors:
in said first position, optically reflects a signal received from a first one of said respective sub-beams back to said first one of said respective sub-beams;
in said second position, optically couples said first one to a second one of said respective sub-beams; and in said third position, optically couples said first one to a third one of said respective sub-beams.
three optical beams;
a wavelength-dispersive medium dispersing wavelength components of said three optical beams incident thereupon into respective wavelength-dispersed sub-beams;
an array of tiltable mirrors having reflective surfaces angularly movable between a first position, a second position, and a third position; and a lens focusing said sub-beams of a respective wavelength upon a respective one of said mirrors;
wherein a respective one of said mirrors:
in said first position, optically reflects a signal received from a first one of said respective sub-beams back to said first one of said respective sub-beams;
in said second position, optically couples said first one to a second one of said respective sub-beams; and in said third position, optically couples said first one to a third one of said respective sub-beams.
12. The switching system of Claim 11, wherein said three beams are propagating generally in parallel within a plane.
13. The switching system of Claim 12, wherein said beams are unequally spaced in said plane.
14. A communications network, comprising a first optical path including optical fiber and a switching node including an optical switch comprising:
a first optical beam receiving an input signal from said first optical path;
a second optical beam transmitting output signal to said first optical path;
a third optical beam for selectively receiving said input signal from said first optical path and transmitting it to a third, optical path;
a fourth optical beam for selectively receiving an add signal from a fourth optical path and transmitting it to said first optical path;
a wavelength-dispersive medium dispersing wavelength components of said four optical beams incident thereupon into respective wavelength-dispersed sub-beams;
an array of tiltable mirrors having reflective surfaces angularly movable between a first position and a second position; and a lens focusing said sub-beams of a respective wavelength upon a respective one of said mirrors;
wherein a respective one of said minors:
in said first position, optically couples a first one to a second one of said respective sub-beams; and in said second position, optically couples said first one to a third one of said respective sub-beams and optically couples said second one to a fourth one of said respective sub-beams.
a first optical beam receiving an input signal from said first optical path;
a second optical beam transmitting output signal to said first optical path;
a third optical beam for selectively receiving said input signal from said first optical path and transmitting it to a third, optical path;
a fourth optical beam for selectively receiving an add signal from a fourth optical path and transmitting it to said first optical path;
a wavelength-dispersive medium dispersing wavelength components of said four optical beams incident thereupon into respective wavelength-dispersed sub-beams;
an array of tiltable mirrors having reflective surfaces angularly movable between a first position and a second position; and a lens focusing said sub-beams of a respective wavelength upon a respective one of said mirrors;
wherein a respective one of said minors:
in said first position, optically couples a first one to a second one of said respective sub-beams; and in said second position, optically couples said first one to a third one of said respective sub-beams and optically couples said second one to a fourth one of said respective sub-beams.
15. A switching method, comprising the steps of:
for a first, a second, a third, and a fourth beam, wavelength dispersing each of said beams into a plurality of corresponding first, second, third, and fourth sub-beams of different wavelengths;
directing each of said sub-beams having a respective wavelength toward a respective one of a plurality of mirrors;
selectively tilting each of said mirrors between two positions, wherein, in said first position, said respective mirror optically couples said respective first and second sub-beams, and wherein, in said second position, said respective mirror optically couples said respective first and third sub-beams and optically couples said respective second and fourth sub-beams.
for a first, a second, a third, and a fourth beam, wavelength dispersing each of said beams into a plurality of corresponding first, second, third, and fourth sub-beams of different wavelengths;
directing each of said sub-beams having a respective wavelength toward a respective one of a plurality of mirrors;
selectively tilting each of said mirrors between two positions, wherein, in said first position, said respective mirror optically couples said respective first and second sub-beams, and wherein, in said second position, said respective mirror optically couples said respective first and third sub-beams and optically couples said respective second and fourth sub-beams.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US09/013,842 US5960133A (en) | 1998-01-27 | 1998-01-27 | Wavelength-selective optical add/drop using tilting micro-mirrors |
| US09/013,842 | 1998-01-27 | ||
| PCT/US1999/001620 WO1999038348A1 (en) | 1998-01-27 | 1999-01-27 | Wavelength-selective optical add/drop using tilting micro-mirrors |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2318080A1 CA2318080A1 (en) | 1999-07-29 |
| CA2318080C true CA2318080C (en) | 2003-08-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002318080A Expired - Fee Related CA2318080C (en) | 1998-01-27 | 1999-01-27 | Wavelength-selective optical add/drop using tilting micro-mirrors |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5960133A (en) |
| EP (1) | EP1051876A1 (en) |
| AU (1) | AU2471799A (en) |
| CA (1) | CA2318080C (en) |
| WO (1) | WO1999038348A1 (en) |
Families Citing this family (216)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6097859A (en) | 1998-02-12 | 2000-08-01 | The Regents Of The University Of California | Multi-wavelength cross-connect optical switch |
| FR2781320B1 (en) * | 1998-07-06 | 2000-08-18 | Alsthom Cge Alcatel | DEVICE FOR COMPENSATING THE POLARIZATION DISPERSION OF THE CHANNELS IN A WAVELENGTH MULTIPLEXED SIGNAL |
| US6108471A (en) * | 1998-11-17 | 2000-08-22 | Bayspec, Inc. | Compact double-pass wavelength multiplexer-demultiplexer having an increased number of channels |
| US6310990B1 (en) | 2000-03-16 | 2001-10-30 | Cidra Corporation | Tunable optical structure featuring feedback control |
| US6721508B1 (en) | 1998-12-14 | 2004-04-13 | Tellabs Operations Inc. | Optical line terminal arrangement, apparatus and methods |
| US6342960B1 (en) * | 1998-12-18 | 2002-01-29 | The Boeing Company | Wavelength division multiplex transmitter |
| CA2361133A1 (en) | 1999-02-23 | 2000-09-08 | Jds Uniphase Corporation | Hybrid wavelength selective optical router and switch |
| US6263123B1 (en) * | 1999-03-12 | 2001-07-17 | Lucent Technologies | Pixellated WDM optical components |
| US6292281B1 (en) * | 1999-03-24 | 2001-09-18 | Tellium, Inc. | Protection for MEMS cross-bar switch |
| US6826330B1 (en) | 1999-08-11 | 2004-11-30 | Lightconnect, Inc. | Dynamic spectral shaping for fiber-optic application |
| US6501600B1 (en) | 1999-08-11 | 2002-12-31 | Lightconnect, Inc. | Polarization independent grating modulator |
| EP1203463A2 (en) * | 1999-08-11 | 2002-05-08 | Lightconnect, Inc. | Dynamic spectral shaping in optical fibre communication |
| US6337935B1 (en) * | 1999-08-16 | 2002-01-08 | Lucent Technologies | Dispersed image inverting optical wavelength multiplexer |
| EP1157584A1 (en) | 1999-08-23 | 2001-11-28 | Optical Coating Laboratory, Inc. | Hybrid optical add/drop multiplexing devices |
| US6408120B1 (en) * | 1999-10-20 | 2002-06-18 | Agere Systems Guardian Corp. | Fiber array alignment arrangement |
| US6724512B2 (en) | 1999-11-03 | 2004-04-20 | Optodot Corporation | Optical switch device |
| CA2389729A1 (en) | 1999-11-03 | 2001-05-25 | Optodot Corporation | Optical scanner |
| US6583916B2 (en) * | 1999-11-03 | 2003-06-24 | Optodot Corporation | Optical shutter assembly |
| US6501877B1 (en) * | 1999-11-16 | 2002-12-31 | Network Photonics, Inc. | Wavelength router |
| US6535311B1 (en) * | 1999-12-09 | 2003-03-18 | Corning Incorporated | Wavelength selective cross-connect switch using a MEMS shutter array |
| WO2001048961A1 (en) * | 1999-12-27 | 2001-07-05 | Optical Technologies U.S.A. Corp. | Optical apparatus for dropping and/or adding optical signals |
| US6253001B1 (en) * | 2000-01-20 | 2001-06-26 | Agilent Technologies, Inc. | Optical switches using dual axis micromirrors |
| US6407851B1 (en) | 2000-08-01 | 2002-06-18 | Mohammed N. Islam | Micromechanical optical switch |
| US6498872B2 (en) * | 2000-02-17 | 2002-12-24 | Jds Uniphase Inc. | Optical configuration for a dynamic gain equalizer and a configurable add/drop multiplexer |
| US20010046350A1 (en) * | 2000-02-25 | 2001-11-29 | Tedesco James M. | Configurable Wavelength routing device |
| CA2300780C (en) * | 2000-03-15 | 2007-08-07 | Nortel Networks Corporation | Integrated photonic switch |
| US6542656B1 (en) | 2000-04-05 | 2003-04-01 | Jds Uniphase Corporation | Add-drop optical switches including parallel fixed and movable reflectors and methods of fabricating same |
| US6445842B1 (en) | 2000-04-05 | 2002-09-03 | Jds Uniphase, Inc. | Microelectromechanical optical cross-connect switches including mechanical actuators and methods of operating same |
| US6456751B1 (en) | 2000-04-13 | 2002-09-24 | Calient Networks, Inc. | Feedback stabilization of a loss optimized switch |
| WO2001086825A2 (en) * | 2000-04-28 | 2001-11-15 | Confluent Photonics, Inc. | Miniature monolithic optical devices for dwdm |
| US6496616B2 (en) | 2000-04-28 | 2002-12-17 | Confluent Photonics, Inc. | Miniature monolithic optical demultiplexer |
| US6453087B2 (en) | 2000-04-28 | 2002-09-17 | Confluent Photonics Co. | Miniature monolithic optical add-drop multiplexer |
| US6434291B1 (en) | 2000-04-28 | 2002-08-13 | Confluent Photonics Corporations | MEMS-based optical bench |
| US6631222B1 (en) | 2000-05-16 | 2003-10-07 | Photuris, Inc. | Reconfigurable optical switch |
| AU2001266585A1 (en) * | 2000-05-16 | 2001-11-26 | Photuris, Inc. | A reconfigurable optical switch |
| US6585383B2 (en) | 2000-05-18 | 2003-07-01 | Calient Networks, Inc. | Micromachined apparatus for improved reflection of light |
| US6433911B1 (en) * | 2000-05-19 | 2002-08-13 | Massachusetts Institute Of Technology | Frustrated total internal reflection-based micro-opto-electro-mechanical modulator/demodulator |
| US6560384B1 (en) | 2000-06-01 | 2003-05-06 | Calient Networks, Inc. | Optical switch having mirrors arranged to accommodate freedom of movement |
| US6668108B1 (en) | 2000-06-02 | 2003-12-23 | Calient Networks, Inc. | Optical cross-connect switch with integrated optical signal tap |
| JP4460042B2 (en) * | 2000-07-07 | 2010-05-12 | 古河電気工業株式会社 | Optical switch module |
| US6525864B1 (en) | 2000-07-20 | 2003-02-25 | Nayna Networks, Inc. | Integrated mirror array and circuit device |
| US6763163B1 (en) * | 2000-07-26 | 2004-07-13 | Lucent Technologies Inc. | Method and apparatus for spatial-shift wavelength multiplexing in communication systems |
| AU2001282416A1 (en) * | 2000-07-27 | 2002-02-13 | Civcom Devices & Systems Ltd. | Data processing using polarization-based optical switching and broadcasting |
| US6795605B1 (en) * | 2000-08-01 | 2004-09-21 | Cheetah Omni, Llc | Micromechanical optical switch |
| US6810176B2 (en) | 2000-08-07 | 2004-10-26 | Rosemount Inc. | Integrated transparent substrate and diffractive optical element |
| US7003187B2 (en) | 2000-08-07 | 2006-02-21 | Rosemount Inc. | Optical switch with moveable holographic optical element |
| US6580845B1 (en) | 2000-08-11 | 2003-06-17 | General Nutronics, Inc. | Method and device for switching wavelength division multiplexed optical signals using emitter arrays |
| US6643425B1 (en) | 2000-08-17 | 2003-11-04 | Calient Networks, Inc. | Optical switch having switch mirror arrays controlled by scanning beams |
| US6636655B2 (en) | 2000-08-29 | 2003-10-21 | Memscap S.A. | MEMS optical switches having obliquely angled inputs and outputs relative to a face thereof and moveable reflectors with parallel positions therein and methods of forming same |
| US6845187B1 (en) | 2000-09-08 | 2005-01-18 | Pts Corporation | Linear optical beam translator for optical routing |
| EP1189476A1 (en) * | 2000-09-13 | 2002-03-20 | Corning Incorporated | Multi-order optical cross-connect |
| US6411424B1 (en) * | 2000-09-18 | 2002-06-25 | Intel Corporation | Integrated laser array devices |
| AU2001292895A1 (en) * | 2000-09-22 | 2002-04-02 | Movaz Networks, Inc. | Variable transmission multi-channel optical switch |
| US6825967B1 (en) | 2000-09-29 | 2004-11-30 | Calient Networks, Inc. | Shaped electrodes for micro-electro-mechanical-system (MEMS) devices to improve actuator performance and methods for fabricating the same |
| US6532318B1 (en) * | 2000-10-18 | 2003-03-11 | Corning Incorporated | Symmetric wavelength selective switch for interconnecting two WDM rings |
| US7324647B1 (en) | 2000-10-23 | 2008-01-29 | Bbn Technologies Corp. | Quantum cryptographic key distribution networks with untrusted switches |
| DE10053498A1 (en) * | 2000-10-27 | 2002-05-16 | Zeiss Carl | Cross coupler for optical communications |
| US6647164B1 (en) | 2000-10-31 | 2003-11-11 | 3M Innovative Properties Company | Gimbaled micro-mirror positionable by thermal actuators |
| US8457501B2 (en) * | 2000-11-03 | 2013-06-04 | Altera Corporation | Reduction of polarization-dependent loss in double-pass grating configurations |
| US6751415B1 (en) | 2000-11-03 | 2004-06-15 | Pts Corporation | Reduction of polarization-dependent loss from grating used in double-pass configuration |
| US6671428B1 (en) * | 2000-12-01 | 2003-12-30 | Bayspec, Inc. | Wavelength selective optical cross switch and optical add/drop multiplexer using volume phase grating and array of micro electro mechanical mirrors |
| US6678445B2 (en) | 2000-12-04 | 2004-01-13 | Jds Uniphase Corporation | Dynamic gain flattening filter |
| US6535664B1 (en) * | 2000-12-20 | 2003-03-18 | Network Photonics, Inc. | 1×2 optical wavelength router |
| US6542657B2 (en) | 2000-12-20 | 2003-04-01 | Network Photonics, Inc. | Binary switch for an optical wavelength router |
| US6873755B2 (en) | 2000-12-20 | 2005-03-29 | Pts Corporation | Wavelength router with staggered input/output fibers |
| US6901200B2 (en) * | 2000-12-22 | 2005-05-31 | Fiber Optic Network Solutions, Inc. | Module and housing for optical fiber distribution and DWDM equipment |
| US7136588B1 (en) * | 2000-12-22 | 2006-11-14 | Cheetah Omni, Llc | Apparatus and method for optical add/drop multiplexing |
| US6731833B2 (en) | 2001-01-16 | 2004-05-04 | T-Rex Enterprises Corp. | Optical cross connect switch |
| WO2002071671A2 (en) * | 2001-01-22 | 2002-09-12 | Essex Corporation | Wavelength division multiplexing add-drop multiplexer using an optical tapped delay line |
| US6807329B2 (en) * | 2001-07-17 | 2004-10-19 | Civcom Devices & Systems Ltd. | Method and device for polarization-based all-optical switching |
| US20050174639A1 (en) * | 2001-01-22 | 2005-08-11 | Zeev Zalevsky | Fast all-optical switches and attenuators |
| US6483957B1 (en) | 2001-01-29 | 2002-11-19 | 3M Innovative Properties Company | MEMS-based polarization mode dispersion compensator |
| US6711318B2 (en) | 2001-01-29 | 2004-03-23 | 3M Innovative Properties Company | Optical switch based on rotating vertical micro-mirror |
| US6445502B1 (en) * | 2001-02-02 | 2002-09-03 | Celeste Optics, Inc. | Variable blazed grating |
| US7145704B1 (en) | 2003-11-25 | 2006-12-05 | Cheetah Omni, Llc | Optical logic gate based optical router |
| US7339714B1 (en) | 2001-02-02 | 2008-03-04 | Cheetah Omni, Llc | Variable blazed grating based signal processing |
| US6721473B1 (en) | 2001-02-02 | 2004-04-13 | Cheetah Omni, Llc | Variable blazed grating based signal processing |
| US6766081B2 (en) * | 2001-02-13 | 2004-07-20 | Pts Corporation | Focal length dispersion compensation for field curvature |
| FR2821670B1 (en) * | 2001-03-02 | 2004-07-09 | Jobin Yvon Sas | SPECTROMETER WITH ADAPTABLE RESPONSE BY ACTIVE MATRIX OPTICS |
| US7330659B2 (en) * | 2001-03-02 | 2008-02-12 | Lucent Technologies Inc. | Wavelength filter that operates on sets of wavelength channels |
| US6792177B2 (en) | 2001-03-12 | 2004-09-14 | Calient Networks, Inc. | Optical switch with internal monitoring |
| WO2002075997A1 (en) * | 2001-03-16 | 2002-09-26 | Photuris, Inc. | Wavelength division multiplexed optical communication system having a reconfigurable optical switch and a tunable backup laser transmitter |
| US6625346B2 (en) * | 2001-03-19 | 2003-09-23 | Capella Photonics, Inc. | Reconfigurable optical add-drop multiplexers with servo control and dynamic spectral power management capabilities |
| WO2002075410A1 (en) * | 2001-03-19 | 2002-09-26 | Capella Photonics, Inc. | Reconfigurable optical add-drop multiplexers |
| US6549699B2 (en) | 2001-03-19 | 2003-04-15 | Capella Photonics, Inc. | Reconfigurable all-optical multiplexers with simultaneous add-drop capability |
| US6760511B2 (en) * | 2001-03-19 | 2004-07-06 | Capella Photonics, Inc. | Reconfigurable optical add-drop multiplexers employing polarization diversity |
| US6636654B2 (en) | 2001-03-30 | 2003-10-21 | Optical Research Associates | Programmable optical switching add/drop multiplexer |
| CA2443356A1 (en) * | 2001-04-03 | 2002-10-17 | Cidra Corporation | Dynamic optical filter having a spatial light modulator |
| US20020176149A1 (en) * | 2001-04-03 | 2002-11-28 | Michael Davis | Variable optical source |
| US6490384B2 (en) * | 2001-04-04 | 2002-12-03 | Yoon-Joong Yong | Light modulating system using deformable mirror arrays |
| US6694073B2 (en) | 2001-04-13 | 2004-02-17 | Movaz Networks, Inc. | Reconfigurable free space wavelength cross connect |
| US20030007202A1 (en) * | 2001-05-09 | 2003-01-09 | Ondax, Inc. | Microelectromechanical system (MEMS) based tunable hitless add-drop filter |
| US6608712B2 (en) | 2001-05-15 | 2003-08-19 | Network Photonics, Inc. | Hidden flexure ultra planar optical routing element |
| US6859578B2 (en) * | 2001-05-18 | 2005-02-22 | Nuonics, Inc. | Fault-tolerant fiber-optical multiwavelength processor |
| US6543087B2 (en) | 2001-06-01 | 2003-04-08 | Aip Networks, Inc. | Micro-electromechanical hinged flap structure |
| US20070047113A1 (en) * | 2001-06-02 | 2007-03-01 | Capella Photonics, Inc. | High fill-factor bulk silicon mirrors with reduced effect of mirror edge diffraction |
| US6882766B1 (en) | 2001-06-06 | 2005-04-19 | Calient Networks, Inc. | Optical switch fabric with redundancy |
| US6600591B2 (en) | 2001-06-12 | 2003-07-29 | Network Photonics, Inc. | Micromirror array having adjustable mirror angles |
| US6771851B1 (en) | 2001-06-19 | 2004-08-03 | Nayna Networks | Fast switching method for a micro-mirror device for optical switching applications |
| US6657770B2 (en) * | 2001-06-22 | 2003-12-02 | Lucent Technologies Inc. | Programmable optical multiplexer/demultiplexer |
| US6950609B2 (en) * | 2001-06-22 | 2005-09-27 | Lucent Technologies Inc. | Tunable, multi-port optical add-drop multiplexer |
| US6674584B2 (en) | 2001-07-03 | 2004-01-06 | Pts Corporation | Optical surface-mount lens cell |
| US6625342B2 (en) | 2001-07-03 | 2003-09-23 | Network Photonics, Inc. | Systems and methods for overcoming stiction using a lever |
| US6657759B2 (en) | 2001-07-03 | 2003-12-02 | Pts Corporation | Bistable micromirror with contactless stops |
| US6873447B2 (en) | 2001-07-03 | 2005-03-29 | Pts Corporation | Two-dimensional free-space optical wavelength routing element based on stepwise controlled tilting mirrors |
| US6535319B2 (en) | 2001-07-03 | 2003-03-18 | Network Photonics, Inc. | Free-space optical wavelength routing element based on stepwise controlled tilting mirrors |
| US7042609B2 (en) * | 2001-07-03 | 2006-05-09 | Pts Corporation | Two-dimensional stepwise-controlled microstructure |
| US6701037B2 (en) | 2001-07-03 | 2004-03-02 | Pts Corporation | MEMS-based noncontacting free-space optical switch |
| US6614581B2 (en) | 2001-07-03 | 2003-09-02 | Network Photonics, Inc. | Methods and apparatus for providing a multi-stop micromirror |
| US6778739B1 (en) | 2001-07-05 | 2004-08-17 | Calient Networks | Wavelength selective optical switch with aligned input and output substrates |
| WO2003009032A1 (en) | 2001-07-20 | 2003-01-30 | Essex Corporation | Method and apparatus for optical signal processing using an optical tapped delay line |
| US7110633B1 (en) | 2001-08-13 | 2006-09-19 | Calient Networks, Inc. | Method and apparatus to provide alternative paths for optical protection path switch arrays |
| US7298540B2 (en) * | 2001-08-22 | 2007-11-20 | Avanex Corporation | Equalizing optical wavelength routers |
| US6439728B1 (en) | 2001-08-28 | 2002-08-27 | Network Photonics, Inc. | Multimirror stack for vertical integration of MEMS devices in two-position retroreflectors |
| US7164859B2 (en) * | 2001-08-29 | 2007-01-16 | Capella Photonics, Inc. | Free-space dynamic wavelength routing systems with interleaved channels for enhanced performance |
| US7068790B1 (en) | 2001-08-31 | 2006-06-27 | Bbn Technologies Corp. | Systems and methods for path set-up in a quantum key distribution network |
| US7016098B2 (en) * | 2001-08-31 | 2006-03-21 | Lucent Technologies Inc. | Optical device with configurable channel allocation |
| GB0121308D0 (en) | 2001-09-03 | 2001-10-24 | Thomas Swan & Company Ltd | Optical processing |
| EP1298467B1 (en) * | 2001-09-10 | 2004-12-29 | JDS Uniphase, Inc | Optical wavelength selective switch without distortion of unblocked channels |
| WO2003028265A2 (en) * | 2001-09-25 | 2003-04-03 | Cidra Corporation | Reconfigurable optical add/drop multiplexer having an array of micro-mirrors |
| US7203421B2 (en) * | 2001-09-28 | 2007-04-10 | Optical Research Associates | Littrow grating based OADM |
| US6597825B1 (en) | 2001-10-30 | 2003-07-22 | Calient Networks, Inc. | Optical tap for an optical switch |
| US6747799B2 (en) | 2001-11-12 | 2004-06-08 | Pts Corporation | High-efficiency low-polarization-dependent-loss lamellar diffraction-grating profile and production process |
| US6798951B2 (en) * | 2001-11-12 | 2004-09-28 | Pts Corporation | Wavelength router with a transmissive dispersive element |
| US6879749B2 (en) * | 2001-11-27 | 2005-04-12 | Ec-Optics Technology Inc. | System and method for multiplexing and demultiplexing optical signals using diffraction gratings |
| US6847749B1 (en) | 2002-01-18 | 2005-01-25 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Diffraction-based optical switch |
| US20040208584A1 (en) * | 2002-01-29 | 2004-10-21 | Keller Robert C. | Reconfigurable optical add-drop multiplexer using an analog mirror device |
| US6987901B2 (en) * | 2002-03-01 | 2006-01-17 | Rosemount, Inc. | Optical switch with 3D waveguides |
| US6813408B2 (en) * | 2002-03-08 | 2004-11-02 | Pts Corporation | Methods for performing in-service upgrades of optical wavelength cross connects |
| US7155084B2 (en) * | 2002-05-17 | 2006-12-26 | Altera Corporation | Bidirectional wavelength cross connect architectures using wavelength routing elements |
| US6990268B2 (en) * | 2002-03-08 | 2006-01-24 | Pts Corporation | Optical wavelength cross connect architectures using wavelength routing elements |
| US8086101B2 (en) * | 2002-03-08 | 2011-12-27 | Altera Corporation | Multi-city DWDM wavelength link architectures and methods for upgrading |
| US7079723B2 (en) * | 2002-03-08 | 2006-07-18 | Pts Corporation | Optical wavelength cross connect architectures using wavelength routing elements |
| US6781730B2 (en) * | 2002-03-11 | 2004-08-24 | Pts Corporation | Variable wavelength attenuator for spectral grooming and dynamic channel equalization using micromirror routing |
| US6690853B1 (en) | 2002-03-11 | 2004-02-10 | Pts Corporation | Tunable DWDM demultiplexer |
| US6959132B2 (en) * | 2002-03-13 | 2005-10-25 | Pts Corporation | One-to-M wavelength routing element |
| US7177498B2 (en) * | 2002-03-13 | 2007-02-13 | Altera Corporation | Two-by-two optical routing element using two-position MEMS mirrors |
| US7194206B2 (en) * | 2002-05-15 | 2007-03-20 | Altera Corporation | Variable-density optical cross-connect architectures and upgrades |
| WO2003098856A2 (en) * | 2002-05-20 | 2003-11-27 | Metconnex Canada Inc. | Reconfigurable optical add-drop module, system and method |
| US6785039B2 (en) | 2002-06-03 | 2004-08-31 | Pts Corporation | Optical routing elements |
| US7058251B2 (en) * | 2002-06-12 | 2006-06-06 | Optical Research Associates | Wavelength selective optical switch |
| US7457416B1 (en) | 2002-07-17 | 2008-11-25 | Bbn Technologies Corp. | Key distribution center for quantum cryptographic key distribution networks |
| US6941073B2 (en) * | 2002-07-23 | 2005-09-06 | Optical Research Associates | East-west separable ROADM |
| US6809384B1 (en) | 2002-08-09 | 2004-10-26 | Pts Corporation | Method and apparatus for protecting wiring and integrated circuit device |
| US7002215B1 (en) | 2002-09-30 | 2006-02-21 | Pts Corporation | Floating entrance guard for preventing electrical short circuits |
| US6825981B2 (en) * | 2002-10-10 | 2004-11-30 | Sumitomo Electric Industries, Ltd. | Optical signal processor |
| US20060222180A1 (en) * | 2002-10-15 | 2006-10-05 | Elliott Brig B | Chip-scale transmitter for quantum cryptography |
| US7627126B1 (en) | 2002-10-15 | 2009-12-01 | Bbn Technologies Corp. | Systems and methods for implementing path length control for quantum cryptographic systems |
| US7184620B1 (en) | 2002-11-27 | 2007-02-27 | Oplink Communications, Inc. | 3-port optical add-drop multiplexer (OADM) |
| US7039271B2 (en) * | 2002-11-27 | 2006-05-02 | Oplink Communications, Inc. | Reduced element optical add-drop multiplexer |
| JP2004233951A (en) * | 2002-12-02 | 2004-08-19 | Seiko Instruments Inc | Optical switch and optical switch device |
| US7088497B1 (en) * | 2002-12-17 | 2006-08-08 | Silicon Light Machines Corporation | Optical device with polarization diversity module |
| US7460670B1 (en) | 2002-12-20 | 2008-12-02 | Bbn Technologies Corp. | Systems and methods for managing quantum cryptographic networks |
| US7236597B2 (en) | 2002-12-20 | 2007-06-26 | Bbn Technologies Corp. | Key transport in quantum cryptographic networks |
| US7277173B1 (en) * | 2002-12-24 | 2007-10-02 | Agere Systems Inc. | Active optical alignment using MEMS mirrors |
| JP3852409B2 (en) | 2003-02-04 | 2006-11-29 | 富士通株式会社 | Optical functional device |
| TWI220733B (en) * | 2003-02-07 | 2004-09-01 | Ind Tech Res Inst | System and a method for stack-caching method frames |
| JP4031998B2 (en) * | 2003-02-20 | 2008-01-09 | 富士通株式会社 | Wavelength multiplexing processor |
| US7203398B2 (en) * | 2003-03-20 | 2007-04-10 | Texas Instruments Incorporated | Compact DMD-based optical module |
| US7430295B1 (en) | 2003-03-21 | 2008-09-30 | Bbn Technologies Corp. | Simple untrusted network for quantum cryptography |
| US20040184615A1 (en) * | 2003-03-21 | 2004-09-23 | Elliott Brig Barnum | Systems and methods for arbitrating quantum cryptographic shared secrets |
| US7706535B1 (en) | 2003-03-21 | 2010-04-27 | Bbn Technologies Corp. | Systems and methods for implementing routing protocols and algorithms for quantum cryptographic key transport |
| US6954563B2 (en) * | 2003-03-28 | 2005-10-11 | Pts Corporation | Optical routing mechanism with integral fiber input/output arrangement on MEMS die |
| CA2523555A1 (en) * | 2003-04-25 | 2004-11-11 | Nikon Corporation | Attenuator device and optical switching device |
| JP4076917B2 (en) * | 2003-06-27 | 2008-04-16 | 富士通株式会社 | Optical wavelength switch having planar optical circuit structure |
| US7254293B1 (en) * | 2003-06-30 | 2007-08-07 | Calient Networks, Inc. | Wavelength routing optical switch |
| US8639069B1 (en) | 2003-06-30 | 2014-01-28 | Calient Technologies, Inc. | Wavelength dependent optical switch |
| US7068877B2 (en) * | 2003-07-10 | 2006-06-27 | Sumitomo Electric Industries, Ltd. | Movable mirror device, dispersion compensator, gain equalizer, and optical ADM apparatus |
| DE10337558A1 (en) * | 2003-08-14 | 2005-03-10 | Leica Microsystems | Optical device and microscope with an optical device |
| US7184666B1 (en) | 2003-10-01 | 2007-02-27 | Ciena Corporation | Reconfigurable optical add-drop multiplexer |
| US6983089B2 (en) * | 2003-11-20 | 2006-01-03 | Sumitomo Electric Industries, Ltd. | Method of fabricating optical signal processor |
| US7515716B1 (en) | 2004-02-26 | 2009-04-07 | Bbn Technologies Corp. | Systems and methods for reserving cryptographic key material |
| US7697693B1 (en) | 2004-03-09 | 2010-04-13 | Bbn Technologies Corp. | Quantum cryptography with multi-party randomness |
| US7408639B1 (en) | 2004-04-23 | 2008-08-05 | Nistica, Inc. | Tunable optical routing systems |
| US7257288B1 (en) | 2004-04-23 | 2007-08-14 | Nistica, Inc. | Tunable optical routing systems |
| JP2005321480A (en) * | 2004-05-06 | 2005-11-17 | Fujitsu Ltd | Wavelength selection device |
| US7272278B2 (en) * | 2004-06-04 | 2007-09-18 | Sumitomo Electric Industries, Ltd. | Optical multiplexer/demultiplexer |
| US7116463B2 (en) * | 2004-07-15 | 2006-10-03 | Optron Systems, Inc. | High angular deflection micro-mirror system |
| JP4445373B2 (en) * | 2004-10-29 | 2010-04-07 | 富士通株式会社 | Light switch |
| JP4530805B2 (en) * | 2004-11-02 | 2010-08-25 | 富士通株式会社 | Optical switch and optical transmission device |
| US7756368B2 (en) * | 2005-04-11 | 2010-07-13 | Capella Photonics, Inc. | Flex spectrum WSS |
| US7346234B2 (en) * | 2005-04-11 | 2008-03-18 | Capella Photonics | Reduction of MEMS mirror edge diffraction in a wavelength selective switch using servo-based multi-axes rotation |
| US7362930B2 (en) * | 2005-04-11 | 2008-04-22 | Capella Photonics | Reduction of MEMS mirror edge diffraction in a wavelength selective switch using servo-based rotation about multiple non-orthogonal axes |
| US7539371B2 (en) | 2005-04-11 | 2009-05-26 | Capella Photonics, Inc. | Optical apparatus with reduced effect of mirror edge diffraction |
| US7263253B2 (en) * | 2005-04-11 | 2007-08-28 | Capella Photonics, Inc. | Optimized reconfigurable optical add-drop multiplexer architecture with MEMS-based attenuation or power management |
| US7352927B2 (en) | 2005-04-11 | 2008-04-01 | Capella Photonics | Optical add-drop multiplexer architecture with reduced effect of mirror edge diffraction |
| US7567756B2 (en) * | 2005-08-03 | 2009-07-28 | Capella Photonics | Method of automatic adjustment of dither amplitude of MEMS mirror arrays |
| US7429983B2 (en) | 2005-11-01 | 2008-09-30 | Cheetah Omni, Llc | Packet-based digital display system |
| US20070130455A1 (en) * | 2005-12-06 | 2007-06-07 | Elliott Brig B | Series encryption in a quantum cryptographic system |
| US20070133798A1 (en) * | 2005-12-14 | 2007-06-14 | Elliott Brig B | Quantum cryptography on a multi-drop optical network |
| US8082443B2 (en) * | 2006-01-09 | 2011-12-20 | Bbnt Solutions Llc. | Pedigrees for quantum cryptography |
| US8000568B2 (en) * | 2006-11-07 | 2011-08-16 | Olympus Corporation | Beam steering element and associated methods for mixed manifold fiberoptic switches |
| US8131123B2 (en) * | 2006-11-07 | 2012-03-06 | Olympus Corporation | Beam steering element and associated methods for manifold fiberoptic switches and monitoring |
| US7769255B2 (en) * | 2006-11-07 | 2010-08-03 | Olympus Corporation | High port count instantiated wavelength selective switch |
| US7702194B2 (en) * | 2006-11-07 | 2010-04-20 | Olympus Corporation | Beam steering element and associated methods for manifold fiberoptic switches |
| US7873246B2 (en) * | 2006-11-07 | 2011-01-18 | Olympus Corporation | Beam steering element and associated methods for manifold fiberoptic switches and monitoring |
| US7720329B2 (en) * | 2006-11-07 | 2010-05-18 | Olympus Corporation | Segmented prism element and associated methods for manifold fiberoptic switches |
| DE102007004514A1 (en) | 2007-01-24 | 2008-07-31 | Schleifring Und Apparatebau Gmbh | Two-channel multimode rotary transmitter |
| DE102007004517A1 (en) * | 2007-01-24 | 2008-07-31 | Schleifring Und Apparatebau Gmbh | Two-channel multimode rotary transformer |
| US8224189B1 (en) | 2007-02-02 | 2012-07-17 | Sunlight Photonics Inc. | Retro-directive target for free-space optical communication and method of producing the same |
| US7864423B2 (en) * | 2007-08-10 | 2011-01-04 | Aegis Lightwave, Inc. | Spectrally adjustable filter |
| US8284489B2 (en) * | 2007-09-11 | 2012-10-09 | Aegis Lightwave, Inc. | Spectrally adjustable filter |
| US7664348B2 (en) * | 2007-12-21 | 2010-02-16 | Teledyne Scientific & Imaging, Llc | Optical switch with reconfigurable broadcasting and combining capabilities |
| US8190025B2 (en) * | 2008-02-28 | 2012-05-29 | Olympus Corporation | Wavelength selective switch having distinct planes of operation |
| US8049885B1 (en) | 2008-05-15 | 2011-11-01 | Ondax, Inc. | Method and apparatus for large spectral coverage measurement of volume holographic gratings |
| US7817272B2 (en) * | 2008-06-09 | 2010-10-19 | Aegis Lightwave, Inc. | High-resolution spectrally adjustable filter |
| US7986407B2 (en) | 2008-08-04 | 2011-07-26 | Ondax, Inc. | Method and apparatus using volume holographic wavelength blockers |
| US8369017B2 (en) | 2008-10-27 | 2013-02-05 | Ondax, Inc. | Optical pulse shaping method and apparatus |
| US8368987B1 (en) * | 2011-09-15 | 2013-02-05 | Nistica, Inc. | Optical processing device |
| US9849034B2 (en) | 2011-11-07 | 2017-12-26 | Alcon Research, Ltd. | Retinal laser surgery |
| ES2569257T3 (en) * | 2011-12-09 | 2016-05-09 | Alcon Research, Ltd. | Devices and procedures for reconfigurable multi-point scanning |
| GB2504970A (en) | 2012-08-15 | 2014-02-19 | Swan Thomas & Co Ltd | Optical device and methods to reduce cross-talk |
| US9599565B1 (en) | 2013-10-02 | 2017-03-21 | Ondax, Inc. | Identification and analysis of materials and molecular structures |
| US9329345B2 (en) * | 2013-11-22 | 2016-05-03 | Alcatel Lucent | Hybrid wavelength selective switch |
| US9429712B2 (en) * | 2014-07-23 | 2016-08-30 | Ii-Vi Incorporated | Dual-ganged optical switch |
| US9587983B1 (en) | 2015-09-21 | 2017-03-07 | Ondax, Inc. | Thermally compensated optical probe |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5210635A (en) * | 1989-04-17 | 1993-05-11 | Dainippon Screen Mfg. Co., Ltd. | Multibeam scanning system |
| US5126836A (en) * | 1989-11-01 | 1992-06-30 | Aura Systems, Inc. | Actuated mirror optical intensity modulation |
| US5199088A (en) * | 1991-12-31 | 1993-03-30 | Texas Instruments Incorporated | Fiber optic switch with spatial light modulator device |
| US5307358A (en) * | 1993-05-20 | 1994-04-26 | The United States Of America As Represented By The Secretary Of The Navy | Wavelength dispersive gain element for a tunable laser |
| US5428218A (en) * | 1993-09-30 | 1995-06-27 | The United States Of America As Represented By The Secretary Of The Air Force | Variable time-delay system for broadband phased array and other transversal filtering applications |
| US5550818A (en) * | 1994-09-19 | 1996-08-27 | Bell Communications Research, Inc. | System for wavelength division multiplexing/asynchronous transfer mode switching for network communication |
| IT1267645B1 (en) * | 1994-12-09 | 1997-02-07 | Cselt Centro Studi Lab Telecom | RING COMMUNICATION STRUCTURE ON OPTICAL VECTOR AND RELATIVE RECONFIGURABLE NODE. |
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1999
- 1999-01-27 AU AU24717/99A patent/AU2471799A/en not_active Abandoned
- 1999-01-27 CA CA002318080A patent/CA2318080C/en not_active Expired - Fee Related
- 1999-01-27 WO PCT/US1999/001620 patent/WO1999038348A1/en not_active Application Discontinuation
- 1999-01-27 EP EP99904289A patent/EP1051876A1/en not_active Withdrawn
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| US5960133A (en) | 1999-09-28 |
| AU2471799A (en) | 1999-08-09 |
| CA2318080A1 (en) | 1999-07-29 |
| EP1051876A1 (en) | 2000-11-15 |
| WO1999038348A1 (en) | 1999-07-29 |
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