CA1154137A - Coupling device for coupling signals into or out of a transmission glass-fibre - Google Patents
Coupling device for coupling signals into or out of a transmission glass-fibreInfo
- Publication number
- CA1154137A CA1154137A CA000349580A CA349580A CA1154137A CA 1154137 A CA1154137 A CA 1154137A CA 000349580 A CA000349580 A CA 000349580A CA 349580 A CA349580 A CA 349580A CA 1154137 A CA1154137 A CA 1154137A
- Authority
- CA
- Canada
- Prior art keywords
- lambda
- optical
- grating
- fibre
- phase grating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
- G02B6/4215—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers
-
- 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
- G02B6/29307—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 components assembled in or forming a solid transparent unitary block, e.g. for facilitating component alignment
-
- 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
-
- 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
- G02B6/29311—Diffractive element operating in transmission
-
- 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
- G02B6/29379—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 characterised by the function or use of the complete device
- G02B6/2938—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 characterised by the function or use of the complete device for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2589—Bidirectional transmission
Abstract
PHD. 79-047 ABSTRACT:
A device for coupling a first optical signal of a first wavelength into a transmission glass-fibre and for coupling out a second optical signal, which has at least a second wavelength which differs from the first wavelength and which travels in the transmission glass-fibre in a direction opposite to that of the first optical signal, the optical signals to be coupled in and coupled out travelling in spatially separated further glass fibres comprising an imaging device arranged between the transmission glass-fibre and the further glass fibres, in whose pupil a binary optical grating is disposed, further glass fibres receiving the second optical signals which have been diffracted into the diffraction orders of the grating. The grating takes the form of a phase grating and is arranged on an optical axis which it has in common with the imaging device, It has a duty factor of at least substantially 1: 1 as well as an optical path difference of substantially H = (N-1) h = n1 .lambda. I, where nl , 1,2,3,...
and in addition substantially complies with the requirement (N-l)h = (m1 + ?) .lambda. k where m1 = 0, 1, 2, ...
and k = II, III, ...
A device for coupling a first optical signal of a first wavelength into a transmission glass-fibre and for coupling out a second optical signal, which has at least a second wavelength which differs from the first wavelength and which travels in the transmission glass-fibre in a direction opposite to that of the first optical signal, the optical signals to be coupled in and coupled out travelling in spatially separated further glass fibres comprising an imaging device arranged between the transmission glass-fibre and the further glass fibres, in whose pupil a binary optical grating is disposed, further glass fibres receiving the second optical signals which have been diffracted into the diffraction orders of the grating. The grating takes the form of a phase grating and is arranged on an optical axis which it has in common with the imaging device, It has a duty factor of at least substantially 1: 1 as well as an optical path difference of substantially H = (N-1) h = n1 .lambda. I, where nl , 1,2,3,...
and in addition substantially complies with the requirement (N-l)h = (m1 + ?) .lambda. k where m1 = 0, 1, 2, ...
and k = II, III, ...
Description
~iL54~3~
"Coupling device for coupling signals into or out of a transmission glass-fibre."
The invention relates to a device for coupling a first optical signal of a first wavelength into a trans-mission glass-fibre and for coupling out a seco~d optical signal which travels in the transmission glass-fibre in a 5 direction opposed to that of the first optical signal and -~hich has a second wavelsngth which differs from the first wavelength, the optical signals to be coupled in and coupled out travelling in spatially separated further glass fibres, which de~ice comprise~ an imaging device arranged between the transmission glass-fibre and the further glass fibres, ~ in whose pupil a binary optical grating is situated, - further glass fibres receiving the second optical~signals `diffracted into~the diffraction orders of the grating.
In;the simplest case inforrnation or data-trans-mission~with the aid of glas~s~fibres~ is e~fected as a ~diaLog e between~two sta~ions or terminals E1,~E2 which are connected to;each other by means of the trànsmission glass-fibres. An e~ample of this is a;telephone terminal and ~an as~ociated exchange. For a more effective use of the oapacity o~ the~tran~mission glass-fibres and in order to obtain a more economic system~ it is advantageous if only one transmission glas~-fibre is required for the transmis-sion in both directions. For each subscriber (terminals E1, E2) this presents the problem of coupling optical 25 signals of a first wavelength (transmitted signals) into the transmission glass-fibre and c~upling optical signals of a second wavelength~which differs from the first wave-length (recei~ed signals) out of the transmission glass~
fibre.
Such devices are already known from "SPIE", Vol. 139, Guided Wave optical Systems and Devices (1978)~
pages 63-69, ~or example Fig. 2. The optical sigrlals are . then di~fracted differently b~ a diffraction grating in ~ 413 PHD. 79-047 2 accordance with their wavelengths.
In this way a geometrical separation of the optical signals to be coupled into the transmission glass-fi~re or coupled out of the transmission glass-fibre can be obtained, which signals are transmitted by means of two further glass fibres, to which a transmitter or a detector is coupled.
However, because of the reflection gratings used, the optical signals as they travel through the device are subject to comparatively high losses as a result of reflec-tion and dispersion. In addition, said device has no common optical axis, which leads to constructional and alignment .
problems.
Therefore, it is the object of the invention to provide a device of the aforementioned type, in which the losses of the radiation travelling through it are minimized and which has only one optical axis. ~ ;
Starting.from a device.as described above, these objects are achieved in that the grating takes the form of .
a phase grating and is arranged on an optical axis which it has in common with:the imaging device, that the phase grating having, at least, substantially a duty factor of 1 : 1 and an optical path difference H of at least substan-tially H = (N-l)h - n.l ~ I in which nl = 1, 2, 3, .. , N is the refra~cti~e index of the phase grating material, h the grating height, and ~I the wavelength of the optical signal to be coupled into the transmission glass-fibre, and *hat the phase grating in addition at least substantiall~
complies with the requirement (N-l)h = (ml ~ ~) A k where mI = ~ 1, 2, ...
and k - II, III, ...
In the device in ac.cordance with the in~ention the particular choice of. the optical path difference H
of the transparen.t phase grating which is disposed in the pupil of the ima.gin.g device ensures that a transmitted signal of a first wa~elength A I~ which issues.from a .
~L5~137 glass fibre (transmi-tting fibre) which is di~sposed on the optical axis, is coupled into a transmission glass-fibre situated on the optical axis at the other side of the device~ without the transmitted signal being in~luenced by the phase grating.
However, an optical signal of a second wavelength ~ II to be coupled out of the transmission glass-fibre) and travelling in a direction opposed to that Or the ~irst optical sig~al,~is influenced by the phase grating in such a way that it is diffracted into the ~lst and -1st di~rac tion orders. The radiation which has been di~fracted into ~the two grating orders is then coupled into other further glass ~ibres (receiving fibres) and applied to a common detector.
The phase grating itself i9 ;of the binary type and at least substantiaIly has a duty~factor of 1 : 1.
Such a phase grating has a~ grating structure wibh only two dif~erent grating heights (meander-shaped phase grating), In the case o~ a duty factor of 1 : 1 such structures have 20;the~same planar~dimension within one grating period. There-fore, such a phase grating can be manu~actured~very simply.
If the phase grating at least substantially complies with the requirement ~ ~ (N-1)h = (m1 ~ 2) ~k~ where m1 = - 1, 2, :
and k = II~ III, ....
it is achieved that the optical signal of the wavelength ~ II to be coupled out of the transmission glass fibre is diffracted in the +1st and 1st grating orders with 30 maxlmum intensity, so that the detector to which the ~ig-naLs which have been diffracted into the two grating orders are applied, produoes a maximum detector output ~ignal.
The diffraction of radiation of a different wavelangth, ; P III~ ~ IV~ into ths ~1st and ~1st diffrac-35 tion orders oan be optimized in a similar way if this re-quirement is met.
In a further advantageous embodiment o~ the in--vention the pha9e grating is located between two lenses . .
~ .
. .
l~S~1.3~
PHD 79 o47 4 25-3-1980 arranged on the optical axis, which lenses take the form of selfoc lenses. Selfoc lenses are cylindrioal lenses, whose optical axis is the cylinder axis and which have such a radial refractive-index profile that a light point situated on the optical axis and on the entrance surface of the selfoc lens can leave the selfoc lens, which for this purpose has a specific length~ as a parallel radiation beam. ~y means of such lenses devices of the said type can be constructed in a particularly compact and stable manner.
In a further advantageous embodiment of the in-vention the phase grating i9 formed in one of t~e ~acing surfaces of the selfoc lenses, so that the separate manu-facture of a phase grating and its alignment between the sel~oc lenses may be dispensed~with.~The phase grating can for example be formed by means o~ photolithographic tech-niques in combination with wet chemical etching or with reactive sputtering.
In the case of reactive sputtering the glass or quartz surface* exposed during the photolithographic pro-20 cess are~removed~in that a reactive substance enters into a volatile compound with the surface material. The resul- -~;
ting structure has very sharp edges.
~ The drawing shows an embodiment of the invention.
In the drawing:
Fig, 1 schematically represents an information ~transmissio~ path for operation with two wavelengths~
Fig. 2 represents a device for,coupl:Ln~ optical signals into or out of a transmisYion glas3-fibre, Fig. 3 graphically represants the coupling losses 30 depending on the quotient ~ and . Fig. 4 represents a binary phase grating with a duty factor of 1 : 1.
Fi~. 1 schematioally represents an in~ormation transmission path for operatlon with two wavelengths between 35 two terminals E1, E2, for example, one telephone terminal and one associated exchange. The terminal E1 comprises an optical transmitter S1, which transmits optical signals having a wavelength ~ I~ a detector D2 for receiving optical :
, . . . :
~15~3~
signals of a wavelengt'l~ as well as a device Kl~ which via glass fibres 1 and 2 is respectively con-nected to the transmitter S1 and the detector D2. Said device K1, which is ~urther connected to the transmission glass-fibre 3 which connects the terminals El, E2, serves to couple the transmitted signals of the wavelength ~ I into the trans-mission glass-fibre 3 and at the same time to couple the signals of the wavele.ngth ~II out of the transrnission glass-: fibre 3, which signal.s travel in the transmission glass-~ibre 3 in an opposite direction and are transmitted by the transmitter S2 of the terminal E2, and to appIy them to the~detector D2.
The device K2 in the terminal E2, however, serves to couple signals of the wavelength ~ which have been transmitted ovar:a glass fibre 4 by a transmitter S2, into the~ translnission glass-fibre 3~ whilst it coupla~ signals of the wavelength ~I out o~ the transmission glass-fibre 3 and applies~them to the detector D1 via a glass ~ibre 5.
The two terminals E1, E2 are :thus interoonnected : 20 by a single tra.tIsmission glass-fibre 3 only, ln which:op-~tical signals o~ dif~erent wavelengths ~ II travel in opposite directions. In this way the capacity o~ the transmission glass-fibre 3 is used mo;re effectively, so that uch an information transmission path can be manu*ac-25 tured in~a:more eoonomic manner.
Fig. 2 by way of example shows the de~ice Kl of , the terminal El in more detail. It comp:r.ises two c~lindri-cal sel-foc lenses 7 and ~, which ha~e a.length L and are disposed on a common optical axis 6, between whlch lenses 30 a phase grating 9 with a suitable structu.re is arranged.
The transmission glass-fibre 3 (Flg. 1) is positioned per-pendicularl~ on the outer surface 7a of the selfoc lens 7, ,the contact~sur~aca o~ said fibre with the selfoc lens 7 being concentric with the optical axis 6. The transmis-35 sion glass-~ibre 3 i9 rigidly connected to the selfoc lens 6, ~or example camented.
A transmitting fibre 1 and two receiving ~ibres ~-, 2a, b, whioh connect the detector D2 and the selfoc lens 8, .
~154i3~
PHD 79 0~7 6 25-3-1980 are positioned perpendicularly on the outer surface 8a of the sel~oc lens 8. The cont~ct surface of the transmitt.ing fibre 1 with the .selfoc lens 8 is again concentric with the optical a~is 6, whilst the receiving fibres 2a, b are 5: situated at a distance l, to be speci~ied hereinafter, from the optical axis 6 and receive the radiation of the wave-length A ~I which has been diffracted into the +1st diffrac-tion order by~the phase grating 9. Said rece.iving fibres 2a, b are al90 rigidly connected to the selfoc lens 8, for e~ample b~ cementing.
The sel~oc lenses 7, 8 have such a length L, : that ther convert the point-shaped light source formed on : the outer surfaces 8a and 7a by the glass fibres 1 and ~ in-to parallel rays. ~ithout the phase~grating 9 the glass fibres 1 and 3 would be image~:onto~each other in an 1 : 1 . ratio. : ~ ~
The optical path differe.nce H1 of tha phase grat-~; ~ ing 9 of the~terminal E1 is now~se:leGted so that~it is a mul*iple of the:wavelength ~ I of the optical signals 20~transmitted br the~bransmitter S1.. Thus, the optical path i~
di~ference H1:will be H1 = (N1-1)h1 = n~ where n1 = 1, 2, 3~ 0.. (1) : In this~equation N1 is the refractive index of the material used for~the phase grating 9,~ whilst h1 is the grating :25 height~-(h in;Fig~ 4). By the inclusion of the phase grating ~ ::; 9, the situatiOn does not change ~or the wavelength ~ I~
;:~ . beoause a phase grating 9 with such a phase height H1 will not :influence radiation of the wavelength ~I. The optical signal from the transmitter S1 is thus coupled into the : 30 transmission glass fibre 3 wibhout any sub~tantial radi-ation losse~. Cross-talk betweerl the transmitting and re-ceiving fibres 1 and 2a, b, i.e a transmission of signals ; of the wavelength ~I in the receiving fibres 2a, b, the.n hardly occ~lr 9 .
Hiowe~er, a fraction ~ 1 of the radiation o~ the : wavelength ~ II whioh arrives via the transmis~ion glass flbre 3 and which has for e~ample been transmitted b~ bhe transmitber S2, is coupled into the reoeiving fibres 2a, 2b, `
.
i3~
i~ the distance l1 from the centre of the receivlng fibre.s 2a, b to the optical axis 6 is equal to the spacing o~ the 0th and the ~ 1st dif~ractinn orders o~ the phase grating 9~ i.e. when:
l = ~ ~
1 d1 II ( ) In this equatlo~ i9 the focal length of the Selfoc lens 8 and 11 the grating period (d in ~ig. 4) of the phase grating 9 in the :terminal E1.
The ~raction ~2 1 is ~ound to be ~ 1 = ~ 2 sin 2 ( 1(N1~
in which ~l 1 reaches its maximllm value o.~ 81% i~ thé re-( 1 1)h1 = (m~1 ~ 2)~ in which m = 0 - (4) is ab least substantially met. Pre~erably~ the equa-tions (1):and (4) should he satis~ied~with small values o~
and m1,:~so that the manu*acture~ o~;the phase gratilIg :9 is not complicated by excessively optical path dif~eren-20 ces H1. ~ ~ ~
In the present embodimenb the sel~oc~:lenses 7 and 8;(sel~oc lenses type SSSL ~rom Nippon Sheet Glass Co ;Lts.) and the sel~oc lenses disposed in the two te.rm~Lnals E1, E2 (Fig. 1) have a length of L = 7.85 mm~ a diameter 25~of 2:mm and a ~ocal length o~f:= 3.2 mm. The glass ~ibres 1 through 5,:however~ have an external diameter o~ 100/um.
In the terminal E1 the optical transmitter S1 co~sists o~ a light-emitting diode~ which emits radiation - ~ o~ a wavelength ~ I - 825 nm. A suitable phn.~e grati~g 9 30 in the terminal E1 has a grating height h1 a~ 3.0/um at a grating pexiod o~ :~or example d1 = 20/um - the maximum value d1 is obtained in the oase t:hat the case that the trans-mitting and receiving ~ibres 1, 2a, b ~ust contaot each other. The :~rac~ion ~1 ~ the radiation o~ the wavelength ; 35 ~ II coupled into bhe detector D2 is then 78~u.
The optical transmitter S2 to be arranged in the terminal E2 compr.ises a light-emitbing diode~ which emits : radiation o~ a wavelength ~ II = 1060 ~n, In the terminal ~' -' ~' . ' .... : . , . ~ , .
~5~13~
E2 the phase grating with an optical path difference of H2 = (N2 1)h2 = n2 ~ where n2 = 1, 2, 3, ... (~) has a gratin~ height h2 of 3.86/um for a grating period d~
of al~o 20/um. The fraction
"Coupling device for coupling signals into or out of a transmission glass-fibre."
The invention relates to a device for coupling a first optical signal of a first wavelength into a trans-mission glass-fibre and for coupling out a seco~d optical signal which travels in the transmission glass-fibre in a 5 direction opposed to that of the first optical signal and -~hich has a second wavelsngth which differs from the first wavelength, the optical signals to be coupled in and coupled out travelling in spatially separated further glass fibres, which de~ice comprise~ an imaging device arranged between the transmission glass-fibre and the further glass fibres, ~ in whose pupil a binary optical grating is situated, - further glass fibres receiving the second optical~signals `diffracted into~the diffraction orders of the grating.
In;the simplest case inforrnation or data-trans-mission~with the aid of glas~s~fibres~ is e~fected as a ~diaLog e between~two sta~ions or terminals E1,~E2 which are connected to;each other by means of the trànsmission glass-fibres. An e~ample of this is a;telephone terminal and ~an as~ociated exchange. For a more effective use of the oapacity o~ the~tran~mission glass-fibres and in order to obtain a more economic system~ it is advantageous if only one transmission glas~-fibre is required for the transmis-sion in both directions. For each subscriber (terminals E1, E2) this presents the problem of coupling optical 25 signals of a first wavelength (transmitted signals) into the transmission glass-fibre and c~upling optical signals of a second wavelength~which differs from the first wave-length (recei~ed signals) out of the transmission glass~
fibre.
Such devices are already known from "SPIE", Vol. 139, Guided Wave optical Systems and Devices (1978)~
pages 63-69, ~or example Fig. 2. The optical sigrlals are . then di~fracted differently b~ a diffraction grating in ~ 413 PHD. 79-047 2 accordance with their wavelengths.
In this way a geometrical separation of the optical signals to be coupled into the transmission glass-fi~re or coupled out of the transmission glass-fibre can be obtained, which signals are transmitted by means of two further glass fibres, to which a transmitter or a detector is coupled.
However, because of the reflection gratings used, the optical signals as they travel through the device are subject to comparatively high losses as a result of reflec-tion and dispersion. In addition, said device has no common optical axis, which leads to constructional and alignment .
problems.
Therefore, it is the object of the invention to provide a device of the aforementioned type, in which the losses of the radiation travelling through it are minimized and which has only one optical axis. ~ ;
Starting.from a device.as described above, these objects are achieved in that the grating takes the form of .
a phase grating and is arranged on an optical axis which it has in common with:the imaging device, that the phase grating having, at least, substantially a duty factor of 1 : 1 and an optical path difference H of at least substan-tially H = (N-l)h - n.l ~ I in which nl = 1, 2, 3, .. , N is the refra~cti~e index of the phase grating material, h the grating height, and ~I the wavelength of the optical signal to be coupled into the transmission glass-fibre, and *hat the phase grating in addition at least substantiall~
complies with the requirement (N-l)h = (ml ~ ~) A k where mI = ~ 1, 2, ...
and k - II, III, ...
In the device in ac.cordance with the in~ention the particular choice of. the optical path difference H
of the transparen.t phase grating which is disposed in the pupil of the ima.gin.g device ensures that a transmitted signal of a first wa~elength A I~ which issues.from a .
~L5~137 glass fibre (transmi-tting fibre) which is di~sposed on the optical axis, is coupled into a transmission glass-fibre situated on the optical axis at the other side of the device~ without the transmitted signal being in~luenced by the phase grating.
However, an optical signal of a second wavelength ~ II to be coupled out of the transmission glass-fibre) and travelling in a direction opposed to that Or the ~irst optical sig~al,~is influenced by the phase grating in such a way that it is diffracted into the ~lst and -1st di~rac tion orders. The radiation which has been di~fracted into ~the two grating orders is then coupled into other further glass ~ibres (receiving fibres) and applied to a common detector.
The phase grating itself i9 ;of the binary type and at least substantiaIly has a duty~factor of 1 : 1.
Such a phase grating has a~ grating structure wibh only two dif~erent grating heights (meander-shaped phase grating), In the case o~ a duty factor of 1 : 1 such structures have 20;the~same planar~dimension within one grating period. There-fore, such a phase grating can be manu~actured~very simply.
If the phase grating at least substantially complies with the requirement ~ ~ (N-1)h = (m1 ~ 2) ~k~ where m1 = - 1, 2, :
and k = II~ III, ....
it is achieved that the optical signal of the wavelength ~ II to be coupled out of the transmission glass fibre is diffracted in the +1st and 1st grating orders with 30 maxlmum intensity, so that the detector to which the ~ig-naLs which have been diffracted into the two grating orders are applied, produoes a maximum detector output ~ignal.
The diffraction of radiation of a different wavelangth, ; P III~ ~ IV~ into ths ~1st and ~1st diffrac-35 tion orders oan be optimized in a similar way if this re-quirement is met.
In a further advantageous embodiment o~ the in--vention the pha9e grating is located between two lenses . .
~ .
. .
l~S~1.3~
PHD 79 o47 4 25-3-1980 arranged on the optical axis, which lenses take the form of selfoc lenses. Selfoc lenses are cylindrioal lenses, whose optical axis is the cylinder axis and which have such a radial refractive-index profile that a light point situated on the optical axis and on the entrance surface of the selfoc lens can leave the selfoc lens, which for this purpose has a specific length~ as a parallel radiation beam. ~y means of such lenses devices of the said type can be constructed in a particularly compact and stable manner.
In a further advantageous embodiment of the in-vention the phase grating i9 formed in one of t~e ~acing surfaces of the selfoc lenses, so that the separate manu-facture of a phase grating and its alignment between the sel~oc lenses may be dispensed~with.~The phase grating can for example be formed by means o~ photolithographic tech-niques in combination with wet chemical etching or with reactive sputtering.
In the case of reactive sputtering the glass or quartz surface* exposed during the photolithographic pro-20 cess are~removed~in that a reactive substance enters into a volatile compound with the surface material. The resul- -~;
ting structure has very sharp edges.
~ The drawing shows an embodiment of the invention.
In the drawing:
Fig, 1 schematically represents an information ~transmissio~ path for operation with two wavelengths~
Fig. 2 represents a device for,coupl:Ln~ optical signals into or out of a transmisYion glas3-fibre, Fig. 3 graphically represants the coupling losses 30 depending on the quotient ~ and . Fig. 4 represents a binary phase grating with a duty factor of 1 : 1.
Fi~. 1 schematioally represents an in~ormation transmission path for operatlon with two wavelengths between 35 two terminals E1, E2, for example, one telephone terminal and one associated exchange. The terminal E1 comprises an optical transmitter S1, which transmits optical signals having a wavelength ~ I~ a detector D2 for receiving optical :
, . . . :
~15~3~
signals of a wavelengt'l~ as well as a device Kl~ which via glass fibres 1 and 2 is respectively con-nected to the transmitter S1 and the detector D2. Said device K1, which is ~urther connected to the transmission glass-fibre 3 which connects the terminals El, E2, serves to couple the transmitted signals of the wavelength ~ I into the trans-mission glass-fibre 3 and at the same time to couple the signals of the wavele.ngth ~II out of the transrnission glass-: fibre 3, which signal.s travel in the transmission glass-~ibre 3 in an opposite direction and are transmitted by the transmitter S2 of the terminal E2, and to appIy them to the~detector D2.
The device K2 in the terminal E2, however, serves to couple signals of the wavelength ~ which have been transmitted ovar:a glass fibre 4 by a transmitter S2, into the~ translnission glass-fibre 3~ whilst it coupla~ signals of the wavelength ~I out o~ the transmission glass-fibre 3 and applies~them to the detector D1 via a glass ~ibre 5.
The two terminals E1, E2 are :thus interoonnected : 20 by a single tra.tIsmission glass-fibre 3 only, ln which:op-~tical signals o~ dif~erent wavelengths ~ II travel in opposite directions. In this way the capacity o~ the transmission glass-fibre 3 is used mo;re effectively, so that uch an information transmission path can be manu*ac-25 tured in~a:more eoonomic manner.
Fig. 2 by way of example shows the de~ice Kl of , the terminal El in more detail. It comp:r.ises two c~lindri-cal sel-foc lenses 7 and ~, which ha~e a.length L and are disposed on a common optical axis 6, between whlch lenses 30 a phase grating 9 with a suitable structu.re is arranged.
The transmission glass-fibre 3 (Flg. 1) is positioned per-pendicularl~ on the outer surface 7a of the selfoc lens 7, ,the contact~sur~aca o~ said fibre with the selfoc lens 7 being concentric with the optical axis 6. The transmis-35 sion glass-~ibre 3 i9 rigidly connected to the selfoc lens 6, ~or example camented.
A transmitting fibre 1 and two receiving ~ibres ~-, 2a, b, whioh connect the detector D2 and the selfoc lens 8, .
~154i3~
PHD 79 0~7 6 25-3-1980 are positioned perpendicularly on the outer surface 8a of the sel~oc lens 8. The cont~ct surface of the transmitt.ing fibre 1 with the .selfoc lens 8 is again concentric with the optical a~is 6, whilst the receiving fibres 2a, b are 5: situated at a distance l, to be speci~ied hereinafter, from the optical axis 6 and receive the radiation of the wave-length A ~I which has been diffracted into the +1st diffrac-tion order by~the phase grating 9. Said rece.iving fibres 2a, b are al90 rigidly connected to the selfoc lens 8, for e~ample b~ cementing.
The sel~oc lenses 7, 8 have such a length L, : that ther convert the point-shaped light source formed on : the outer surfaces 8a and 7a by the glass fibres 1 and ~ in-to parallel rays. ~ithout the phase~grating 9 the glass fibres 1 and 3 would be image~:onto~each other in an 1 : 1 . ratio. : ~ ~
The optical path differe.nce H1 of tha phase grat-~; ~ ing 9 of the~terminal E1 is now~se:leGted so that~it is a mul*iple of the:wavelength ~ I of the optical signals 20~transmitted br the~bransmitter S1.. Thus, the optical path i~
di~ference H1:will be H1 = (N1-1)h1 = n~ where n1 = 1, 2, 3~ 0.. (1) : In this~equation N1 is the refractive index of the material used for~the phase grating 9,~ whilst h1 is the grating :25 height~-(h in;Fig~ 4). By the inclusion of the phase grating ~ ::; 9, the situatiOn does not change ~or the wavelength ~ I~
;:~ . beoause a phase grating 9 with such a phase height H1 will not :influence radiation of the wavelength ~I. The optical signal from the transmitter S1 is thus coupled into the : 30 transmission glass fibre 3 wibhout any sub~tantial radi-ation losse~. Cross-talk betweerl the transmitting and re-ceiving fibres 1 and 2a, b, i.e a transmission of signals ; of the wavelength ~I in the receiving fibres 2a, b, the.n hardly occ~lr 9 .
Hiowe~er, a fraction ~ 1 of the radiation o~ the : wavelength ~ II whioh arrives via the transmis~ion glass flbre 3 and which has for e~ample been transmitted b~ bhe transmitber S2, is coupled into the reoeiving fibres 2a, 2b, `
.
i3~
i~ the distance l1 from the centre of the receivlng fibre.s 2a, b to the optical axis 6 is equal to the spacing o~ the 0th and the ~ 1st dif~ractinn orders o~ the phase grating 9~ i.e. when:
l = ~ ~
1 d1 II ( ) In this equatlo~ i9 the focal length of the Selfoc lens 8 and 11 the grating period (d in ~ig. 4) of the phase grating 9 in the :terminal E1.
The ~raction ~2 1 is ~ound to be ~ 1 = ~ 2 sin 2 ( 1(N1~
in which ~l 1 reaches its maximllm value o.~ 81% i~ thé re-( 1 1)h1 = (m~1 ~ 2)~ in which m = 0 - (4) is ab least substantially met. Pre~erably~ the equa-tions (1):and (4) should he satis~ied~with small values o~
and m1,:~so that the manu*acture~ o~;the phase gratilIg :9 is not complicated by excessively optical path dif~eren-20 ces H1. ~ ~ ~
In the present embodimenb the sel~oc~:lenses 7 and 8;(sel~oc lenses type SSSL ~rom Nippon Sheet Glass Co ;Lts.) and the sel~oc lenses disposed in the two te.rm~Lnals E1, E2 (Fig. 1) have a length of L = 7.85 mm~ a diameter 25~of 2:mm and a ~ocal length o~f:= 3.2 mm. The glass ~ibres 1 through 5,:however~ have an external diameter o~ 100/um.
In the terminal E1 the optical transmitter S1 co~sists o~ a light-emitting diode~ which emits radiation - ~ o~ a wavelength ~ I - 825 nm. A suitable phn.~e grati~g 9 30 in the terminal E1 has a grating height h1 a~ 3.0/um at a grating pexiod o~ :~or example d1 = 20/um - the maximum value d1 is obtained in the oase t:hat the case that the trans-mitting and receiving ~ibres 1, 2a, b ~ust contaot each other. The :~rac~ion ~1 ~ the radiation o~ the wavelength ; 35 ~ II coupled into bhe detector D2 is then 78~u.
The optical transmitter S2 to be arranged in the terminal E2 compr.ises a light-emitbing diode~ which emits : radiation o~ a wavelength ~ II = 1060 ~n, In the terminal ~' -' ~' . ' .... : . , . ~ , .
~5~13~
E2 the phase grating with an optical path difference of H2 = (N2 1)h2 = n2 ~ where n2 = 1, 2, 3, ... (~) has a gratin~ height h2 of 3.86/um for a grating period d~
of al~o 20/um. The fraction
2 = 8 sin 2 ( _ _2( 2 1) ) (6) of the radiation o~ the wavelength ~ I coupled into the detector D1.is approximatel~ 77%. The maximum value o~ ~1%
10 would be obtained for 1 (N2~1)h2 = (m2 ~ 2)~ here m2 = 0, 1, 2, ,., Both phase gratings in the terminals E1 and E2 consist of a material with a refractive index N = N1 = N2, which is 1~45.
The distances l1, 12 of the centres of the re-ceiving ~ibres (:for example the receiving:flbres 2a, b in Fig. 2) from the optical axis 6 in the t~o terml.nals ~1, E2, however, are di~ferent (equation 4):when the two phase gratings have:equal:grating periods (d1 = d2). Equal val~les : 20~of l1 and l2:can be obtained by a suitable choice o~ the : ~ grating periods~dl~, d2 of the phase gratings.
Combining~equations 1, 4, 5 and 7 yieIds the following expresAion: .
:: :
1 m1:+ x1 n2 ~25~ : ~2 = -~ (8) . In this equation x1 and x2 result ~rom equation 4 or 7 and :
: ' X1~ X2 ~ -5-~: Fig. 3 is a graphic representation o~ x - xl or 2 depending on~(m1 ~ x) / n1 (contLnuOug line) ~nd on 0 n2/~m2 ~ x) (dashed ltne~) ~or different valueY of m and n~
Taking into account equation 8~ thc quotient ~ ~II may then be plotted on the abscissa. For,;a preselecbed value of I II 1' m1' xj a~ n2~ m2~ x2 may then be-derived from this diagram, In the present embodiment a I/~ II ~ 0.78 is~obtained for ~ = 825 nm and ~I = 1060 nm, A straight line (dotted) which extends from this point on the abscissa interseots the lines m2 = n2 = 2 !
_' .
. . , : , ' . ' ' ! ' ' . ' ' , ~: , ,., . :, ' . ~
~15~13~
PHD 79 0~7 9 25-3-1980 and m1 = 1, n1 = 2, ,Star$ing from these intersectio.ns and horizontal lines (dotted), intersections with the ordinat~
are obtained at different values of X1, x2. These values may be read directly on the second ordinate as losses V
in dB, which occur when the relevant radiation is coupled into the receiving fibres. When light sources of other wavclengths are selected, other values ~or ml, n1, x1 and m~, n2, x2 and thus other losses Vl 9 V2 will be obtained in a similar way h Fig. 4 is a cross-sectional view of the binary transparent phase grating 9 of Fig. 2. .It has a rectangular grating profile with a duty factor of 1 : 1, i.e. a grating period d which for one half is cove:~ed by gra$ing dales 10 and grating hills 11. I$ may for example take the form of a PVC foil grating (see Knop, Optics Comm., Vol. 18, 298 (1976)) or may be etched into one of the facing inner sur-~aces~ of the Selfoc lenses 7 or 8 b~ means o~ photolitho-graphic techniques, The al:Lgned (coupling) devices Kl, K2 with the 20 selfoc lenses~and the phase grating may be moulded in epoxy : resin or another su.itable bonding agent to a block having four outgoing glass fibres 1, 2a, 2b and 3 (see Fig. .2) or 3, 4 and 5a, 5b:(not shown separately) 9 SO that a mecha-nically stable device is obtained which cannot become ; 25 misaligned. The ends of the relevant outgoing glass fibres are then provided with suitable oonnectors, so that the devices Kl, K2 can easily be interconnected and connected to the associated transmitters S1, S2 and detectors D1, D2.
Furthermore, -the Sel~oc lenses may al$ernately 30 be replaced by other lenses or lens systems, b~ means of which the optical signals issueing:from the transmission ; glass fibre 3 are imaged onto the receiving fibres 2a, b or the trans~itted signal leaving the transmitting ~ibre 1 is imaged onto the transmission glass fibre 3. The radiàtion 35 should at least substantially perpendicularly pa~s through the phase grating 9. The glass fibres should then be posl-tioned accordingly by other suitable means. The phase grat-ing may ~or example be arranged in the pupil o~ a biconvex lens or between two~conve~ lenses,
10 would be obtained for 1 (N2~1)h2 = (m2 ~ 2)~ here m2 = 0, 1, 2, ,., Both phase gratings in the terminals E1 and E2 consist of a material with a refractive index N = N1 = N2, which is 1~45.
The distances l1, 12 of the centres of the re-ceiving ~ibres (:for example the receiving:flbres 2a, b in Fig. 2) from the optical axis 6 in the t~o terml.nals ~1, E2, however, are di~ferent (equation 4):when the two phase gratings have:equal:grating periods (d1 = d2). Equal val~les : 20~of l1 and l2:can be obtained by a suitable choice o~ the : ~ grating periods~dl~, d2 of the phase gratings.
Combining~equations 1, 4, 5 and 7 yieIds the following expresAion: .
:: :
1 m1:+ x1 n2 ~25~ : ~2 = -~ (8) . In this equation x1 and x2 result ~rom equation 4 or 7 and :
: ' X1~ X2 ~ -5-~: Fig. 3 is a graphic representation o~ x - xl or 2 depending on~(m1 ~ x) / n1 (contLnuOug line) ~nd on 0 n2/~m2 ~ x) (dashed ltne~) ~or different valueY of m and n~
Taking into account equation 8~ thc quotient ~ ~II may then be plotted on the abscissa. For,;a preselecbed value of I II 1' m1' xj a~ n2~ m2~ x2 may then be-derived from this diagram, In the present embodiment a I/~ II ~ 0.78 is~obtained for ~ = 825 nm and ~I = 1060 nm, A straight line (dotted) which extends from this point on the abscissa interseots the lines m2 = n2 = 2 !
_' .
. . , : , ' . ' ' ! ' ' . ' ' , ~: , ,., . :, ' . ~
~15~13~
PHD 79 0~7 9 25-3-1980 and m1 = 1, n1 = 2, ,Star$ing from these intersectio.ns and horizontal lines (dotted), intersections with the ordinat~
are obtained at different values of X1, x2. These values may be read directly on the second ordinate as losses V
in dB, which occur when the relevant radiation is coupled into the receiving fibres. When light sources of other wavclengths are selected, other values ~or ml, n1, x1 and m~, n2, x2 and thus other losses Vl 9 V2 will be obtained in a similar way h Fig. 4 is a cross-sectional view of the binary transparent phase grating 9 of Fig. 2. .It has a rectangular grating profile with a duty factor of 1 : 1, i.e. a grating period d which for one half is cove:~ed by gra$ing dales 10 and grating hills 11. I$ may for example take the form of a PVC foil grating (see Knop, Optics Comm., Vol. 18, 298 (1976)) or may be etched into one of the facing inner sur-~aces~ of the Selfoc lenses 7 or 8 b~ means o~ photolitho-graphic techniques, The al:Lgned (coupling) devices Kl, K2 with the 20 selfoc lenses~and the phase grating may be moulded in epoxy : resin or another su.itable bonding agent to a block having four outgoing glass fibres 1, 2a, 2b and 3 (see Fig. .2) or 3, 4 and 5a, 5b:(not shown separately) 9 SO that a mecha-nically stable device is obtained which cannot become ; 25 misaligned. The ends of the relevant outgoing glass fibres are then provided with suitable oonnectors, so that the devices Kl, K2 can easily be interconnected and connected to the associated transmitters S1, S2 and detectors D1, D2.
Furthermore, -the Sel~oc lenses may al$ernately 30 be replaced by other lenses or lens systems, b~ means of which the optical signals issueing:from the transmission ; glass fibre 3 are imaged onto the receiving fibres 2a, b or the trans~itted signal leaving the transmitting ~ibre 1 is imaged onto the transmission glass fibre 3. The radiàtion 35 should at least substantially perpendicularly pa~s through the phase grating 9. The glass fibres should then be posl-tioned accordingly by other suitable means. The phase grat-ing may ~or example be arranged in the pupil o~ a biconvex lens or between two~conve~ lenses,
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for coupling a first optical signal of a first wavelength (.lambda. I) into a transmission glass-fibre and for coupling out a second optical signal which travels in the transmission glass-fibre in a direction opposite to that of the first optical signal and which has a second wavelength (.lambda. II) which differs from the first wavelength, the optical signals to be coupled in and coupled out travelling in spatially separated further glass fibres, which device comprises an imaging device arranged between the transmission glass fibre and the further glass fibres, in whose pupil a binary optical grating is situated, fur-ther glass fibres receiving the second optical signals diffracted into the diffraction orders of the grating, characterized in that the grating takes the form of a phase grating and is arranged on an optical axis which it has in common with the imaging device, that the phase grating at least substantially has a transmission ratio of 1 : 1 and an optical path difference (H) of at least substantially H = (N-1)h = n1 .lambda.I in which nl = 1, 2, 3, ..., N
is the refractive index of the phase grating material, h the grating height and .lambda. I the wavelength of the optical signal to be coupled into the transmission glass-fibre, and that the phase grating in addition at least substant-ially complies with the requirement (N-l)h = (m1 + ?).lambda. k where m1 = 0, 1, 2, ...
and k = II, III, ....
is the refractive index of the phase grating material, h the grating height and .lambda. I the wavelength of the optical signal to be coupled into the transmission glass-fibre, and that the phase grating in addition at least substant-ially complies with the requirement (N-l)h = (m1 + ?).lambda. k where m1 = 0, 1, 2, ...
and k = II, III, ....
2. A device as claimed in Claim 1, characterized in that the phase grating is located between two lenses which are arranged on the optical axis.
3. A device as claimed in Claim 2, characterized in that the lenses are selfoc lenses.
4. A device as claimed in Claim 1, characterized in that the phase grating consists of a suitably structured preferably PVC, foil.
5. A device as claimed in Claim 1 or 3, character-ized in that the phase grating is formed in one of the facing surfaces of the selfoc lenses.
6. A device as claimed in Claim 1, characterized in that the transmission glass-fibre as well as the further glass fibres are rigidly connected for example cemented to the outer surfaces of the selfoc lenses.
7. A device as claimed in Claim 6, characterized in that by means of a bonding agent, for example epoxy resin, the selfoc lenses and the phase grating are moulded to a block with the outgoing transmission glass-fibre as well as the further glass fibres.
8. An optical transmission system for the trans-mission of information by means of a transmission glass-fibre operating with two wavelengths, which in a first terminal (El) comprises an optical transmitter (S1) for transmitting radiation of a first wavelength (.lambda. I) and a detector (D2) for receiving radiation of a second wave-length (.lambda.II) and in a second terminal (E2) comprises an optical transmitter (S2) for transmitting radiation of the second wavelength (.lambda. II) and a detector (D1) for receiving radiation of the first wavelength (.lambda. I), and that in the two terminals there is provided a device (K1, K2) as claimed in Claim 1, characterized in that the first device (K1) in the first terminal (E1) comprises a first phase grating with an optical path difference (H1) of (N1-1)h1 = n1 .lambda. I, where n1 = 1,2,...
and the second device (K2) in the second terminal (E2) comprises a second phase grating with an optical path difference (H2) of (N-1)h2 = n2 .lambda. II, where n2 = 1,2,...
and that the first phase grating at least substantially complies with the additional requirement (N1-1)h1 = (m1 + ?) .lambda. II where m1 = 0,1,2,...
and that the second phase grating at least substantially complies with the additional requirement (N2-1)h2 = (m2 + ?) .lambda.I where m2 = 0,1,2,..., N1, N2 are the refractive indices and h1, h2 the grating heights of the first and the second phase grating respect-ively.
and the second device (K2) in the second terminal (E2) comprises a second phase grating with an optical path difference (H2) of (N-1)h2 = n2 .lambda. II, where n2 = 1,2,...
and that the first phase grating at least substantially complies with the additional requirement (N1-1)h1 = (m1 + ?) .lambda. II where m1 = 0,1,2,...
and that the second phase grating at least substantially complies with the additional requirement (N2-1)h2 = (m2 + ?) .lambda.I where m2 = 0,1,2,..., N1, N2 are the refractive indices and h1, h2 the grating heights of the first and the second phase grating respect-ively.
9. An optical transmission system as claimed in Claim 8, characterized in that the ratio .lambda.I/.lambda.II ? 0.78 and that ml = 1 and m2 = n2 = n2 = 2.
10. An optical transmission system as claimed in Claim 9, characterized in that .lambda. I - 82nm and .lambda.II =
1060 nm.
1060 nm.
11. An optical transmission system as claimed in Claim 8, characterized in that the ratio .lambda. II/d1 or .lambda.I/d2 of the wavelengths (.lambda.II,.lambda.I) of the radiation to be coupled out of the transmission glass-fibre to the grating periods (d1, d2) of the first and the second phase grating respectively, is the same.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2916234.3 | 1979-04-21 | ||
| DE19792916234 DE2916234A1 (en) | 1979-04-21 | 1979-04-21 | COUPLING DEVICE COUPLING OPTICAL SIGNALS INTO A OR FROM A TRANSFER FIBER |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1154137A true CA1154137A (en) | 1983-09-20 |
Family
ID=6068951
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000349580A Expired CA1154137A (en) | 1979-04-21 | 1980-04-10 | Coupling device for coupling signals into or out of a transmission glass-fibre |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4362359A (en) |
| JP (1) | JPS55156905A (en) |
| CA (1) | CA1154137A (en) |
| DE (1) | DE2916234A1 (en) |
| FR (1) | FR2454634A1 (en) |
| GB (1) | GB2049219B (en) |
| SE (1) | SE446668B (en) |
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| JPS6049882B2 (en) * | 1977-07-07 | 1985-11-05 | 日本セルフオツク株式会社 | Optical multiplexing/demultiplexing circuit for optical beams |
| US4198117A (en) * | 1976-12-28 | 1980-04-15 | Nippon Electric Co., Ltd. | Optical wavelength-division multiplexing and demultiplexing device |
| US4111524A (en) * | 1977-04-14 | 1978-09-05 | Bell Telephone Laboratories, Incorporated | Wavelength division multiplexer |
| NL7714270A (en) * | 1977-12-22 | 1979-06-26 | Nederlanden Staat | DEVICE FOR COUPLING AT LEAST THREE LIGHT GUIDES. |
| JPS54100752A (en) * | 1978-01-25 | 1979-08-08 | Mitsubishi Electric Corp | Optical device |
| JPS54102136A (en) * | 1978-01-27 | 1979-08-11 | Mitsubishi Electric Corp | Light circuit element |
| JPS54146644A (en) * | 1978-05-09 | 1979-11-16 | Mitsubishi Electric Corp | Light distributor |
-
1979
- 1979-04-21 DE DE19792916234 patent/DE2916234A1/en active Granted
-
1980
- 1980-04-10 CA CA000349580A patent/CA1154137A/en not_active Expired
- 1980-04-18 SE SE8002908A patent/SE446668B/en not_active IP Right Cessation
- 1980-04-18 GB GB8012781A patent/GB2049219B/en not_active Expired
- 1980-04-21 US US06/141,858 patent/US4362359A/en not_active Expired - Lifetime
- 1980-04-21 FR FR8008898A patent/FR2454634A1/en active Granted
- 1980-04-21 JP JP5181180A patent/JPS55156905A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2454634A1 (en) | 1980-11-14 |
| JPS55156905A (en) | 1980-12-06 |
| FR2454634B1 (en) | 1981-11-06 |
| GB2049219B (en) | 1983-04-27 |
| DE2916234C2 (en) | 1987-05-21 |
| US4362359A (en) | 1982-12-07 |
| SE446668B (en) | 1986-09-29 |
| GB2049219A (en) | 1980-12-17 |
| JPS635730B2 (en) | 1988-02-04 |
| DE2916234A1 (en) | 1980-10-30 |
| SE8002908L (en) | 1980-10-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |