WO2002014918A1 - Optical waveguide with minimised cladding mode coupling - Google Patents
Optical waveguide with minimised cladding mode coupling Download PDFInfo
- Publication number
- WO2002014918A1 WO2002014918A1 PCT/AU2001/000976 AU0100976W WO0214918A1 WO 2002014918 A1 WO2002014918 A1 WO 2002014918A1 AU 0100976 W AU0100976 W AU 0100976W WO 0214918 A1 WO0214918 A1 WO 0214918A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- core
- fibre
- uniformity
- spike
- photosensitivity
- Prior art date
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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03694—Multiple layers differing in properties other than the refractive index, e.g. attenuation, diffusion, stress properties
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
- C03B37/01807—Reactant delivery systems, e.g. reactant deposition burners
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
- C03B37/01861—Means for changing or stabilising the diameter or form of tubes or rods
- C03B37/01869—Collapsing
-
- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03622—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only
- G02B6/03627—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only arranged - +
-
- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03661—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 4 layers only
- G02B6/03677—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 4 layers only arranged - + + -
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
- C03B2201/31—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with germanium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2203/00—Fibre product details, e.g. structure, shape
- C03B2203/10—Internal structure or shape details
- C03B2203/22—Radial profile of refractive index, composition or softening point
- C03B2203/26—Parabolic or graded index [GRIN] core profile
-
- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03605—Highest refractive index not on central axis
- G02B6/03611—Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
Landscapes
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Diffracting Gratings Or Hologram Optical Elements (AREA)
Abstract
The present invention provides an optical fibre having a doped silica core and a silica cladding, wherein the core is formed throughout its cross-sectional area to minimise non-uniformity (i.e. a central dip or a spike) in photosensitivity profile of the core. The fibre according to the invention has minimal coupling of lower order modes of light propagation to lossy higher order modes and therefore reduced transmission loss. The invention also provides a method of forming such an optical fibre.
Description
OPTICAL WAVEGUIDE WITH MINIMISED CLADDING MODE
COUPLING
Field of the Invention This invention relates to an optical fibre which provides for minimal coupling of lower order modes of light propagation to lossy higher order modes. The invention has particular application in relation to in-fibre Bragg gratings and the invention is hereinafter described in that context. However, it will be understood that the invention does have broader application, in the context of fibres that contain other structures that modify the propagation of light and in the context of fibres into which gratings and other such structures are to be written.
Background to the Invention
Optical fibres that contain in-core Bragg gratings exhibit coupling of lower order modes of light propagation to higher order cladding modes. In many applications this represents a limiting factor to grating performance, because the coupling appears as an increase in transmission loss at wavelengths shorter than the Bragg wavelength of the grating.
The coupling from the lowest order guided mode to lossy higher order modes may be overcome by providing the fibre with a cladding that has a similar photosensitivity to that of the core over a diameter of at least three times that of the core diameter. However, this is not always expedient and, in any case is only achieved if the photosensitivity is uniform throughout the cross-sectional area of the core.
It has now been recognised by the inventor that the coupling of lower order modes to lossy higher order modes is attributable at least in part to the presence of a non-
uniformity in the photosensitivity in the centre of the core of optical fibre. This non-uniformity occurs inherently as a result of fibre fabrication and/or drawing processes and is manifested by a depression or a spike in the photosensitivity profile at the centre of the fibre core. It has also been recognised by the inventor that the non-uniformity in the photosensitivity profile can be correlated with a non-uniformity in the refractive index profile and, whilst this latter non-uniformity has been recognised in the past, it has for all practical purposes been ignored. Thus, it has in the past been assumed for calculations and other purposes that the photosensitivity throughout the core region of fibre is uniform.
However, as indicated, the inventor has now determined that the non-uniformity in the refractive index profile does, in fact, lead to or correlate with a non-uniform photosensitivity profile, this giving rise to the coupling of lower order modes to lossy higher order modes. From this it has been determined that, by reducing the magnitude of the non-uniformity in the photosensitivity, the coupling into the lossy cladding modes will be reduced.
Summary of the Invention
Broadly defined, the present invention provides an optical fibre having a doped silica core and a silica cladding, wherein the core is formed throughout its cross-sectional area to minimise non-uniformity in the photosensitivity profile of the core. This may be achieved by forming the core such that the average diameter of the non-uniformity is not greater than 30% of the diameter of the core and/or by forming the core in a manner to reduce the amplitude of the non-uniformity in the photosensitivity profile.
The invention may also be defined as providing a method of forming an optical fibre which comprises the steps of:
(a) fabricating a preform by the modified chemical vapour deposition process, and
(b) drawing the fibre from the preform, wherein the step (a) and/or step (b) is/are performed in a manner to form a core which, throughout its cross- sectional area, exhibits a photosensitivity profile having a minimal non-uniformity.
The non-uniformity in the photosensitivity profile will typically comprise a central depression or a spike, and it is the average diameter or amplitude (i.e., depth of height) of such depression or spike that may be limited in size for the purpose of reducing coupling into the cladding mode when a grating or other periodic structure is written into the fibre.
As indicated previously, a non-uniformity in the photosensitivity profile can be correlated with a non- uniformity in the refractive index profile. There may be a direct correlation, in the sense that a depression or spike in the refractive index profile will be accompanied by a similar depression or spike in the photosensitivity profile. However, indications are that there may also be an indirect correlation in some cases, in that a depression or a spike in the refractive index profile may be accompanied by a reverse effect in the photosensitivity profile.
Brief Description of the Drawings The invention will be more fully understood from the following description of preferred embodiments of gratings containing optical fibres having various refractive index profiles, provided by way of example and described with reference to the accompanying drawings, in which: Figure 1 shows a refractive index profile with reference to the fibre radius for a typical optical fibre; Figure 2 shows a transmission spectrum for an optical
fibre Bragg grating with reference to the relative wavelength (i.e. zero .wavelength being the Bragg wavelength) in a low NA fibre;
Figures 3A and 3B are graphs of the refractive index profile/photosensitivity factor as a function of fibre radius for an optical fibre with: (in Figure 3A) a spikelike non-uniformity at the centre of the fibre core resulting from an increase in the concentration of germanium, and (in Figure 3B) a depressed non-uniformity at the centre of the fibre core resulting from a decrease in the concentration of germanium;
Figures 4A and 4B are graphs of the loss to cladding modes in an optical fibre with reference to: (in Figure 4A) relative height in the spike-like non-uniformity in the refractive index, and (in Figure 4B) relative depth in the depressed non-uniformity in the refractive index.
Detailed Description
As indicated previously in this specification, a standard optical fibre has an inherent non-uniformity in photosensitivity throughout the core as a result of the fabrication process. Figure 1 shows a typical refractive index profile (plotted as index difference ID versus radius JR (μ ) ) for a fibre manufactured by the modified chemical vapour deposition (MCVD) process. The refractive index in this case has a non-uniformity in the form of a depression in the centre of the fibre core.
Figure 2 shows a typical transmission spectrum of an in- fibre Bragg grating filter showing the loss to cladding modes for wavelengths shorter than the Bragg wavelength (plotted as transmission T (dB) versus wavelength detuning Δλ (nm) ) , where the fibre has a low NA.
The non-uniformity in the refractive index profile and, hence, in the photosensitivity profile can be controlled by varying the material properties that constitute the
fibre core. For example, in the case of a silica core doped with germanium it is possible - to increase the photosensitivity in the middle of the fibre core by increasing the concentration of germanium in the core. Also, by decreasing the overall concentration of germanium in the fibre core it is possible to decrease the photosensitivity in -the core.
Figure 3A shows the refractive index profile with reference to radius R (μm) for a fibre where the photosensitivity throughout the core is increased.
Refractive index n is plotted with a solid line and calibrated on the left vertical axis, while photosensitivity factor PS is plotted with a dashed line and calibrated on the right vertical axis. From Figure 3A it may be observed that the centre of the fibre core exhibits a non-uniformity in the form of a spike in the refractive index profile as a result of the increase in the photosensitivity. Conversely, Figure 3B exhibits a non-uniformity in the form of a depressed refractive index profile as a result of decreasing the photosensitivity throughout the core.
For the refractive index profile of the fibre shown in Figure 3B the results show that, provided that the diameter of the dip is kept below approximately 30% of the core radius, then losses into cladding modes can be minimised so that they are always less than 0.1 dB. Thus, launching light into a fibre designed with these constraints will ensure that most of the light will propagate in the lowest order guided mode of the fibre, this minimising the losses to cladding modes.
For the refractive index profile of the fibre shown in Figure 3A, which exhibits a spike-like non-uniformity in the centre of the core, the results are similar to those for the fibre with a dip as shown in Figure 3B. Provided
_ s _ .
the diameter of the spike . is always less than 30% of the fibre core then losses to cladding modes can be minimised. However, this fibre has been found to be less sensitive to the relative size of the spike-like non-uniformity.
Figures 4A and 4B show the maximum cladding mode loss L (dB) , with reference to the relative spike height h (i.e. normalized to the refractive index of the core) in Figure 4A and to the relative dip depth d (again, normalized to the refractive index of the core) in Figure 4B, for the refractive index profiles of the fibres shown in Figure 3A and Figure 3B respectively (and, in both cases, with no blaze and with cladding photosensitivity matched to the core) . In Figures 4A and 4B the width of the spike or dip is taken to be the full width of the spike of the dip at half the maximum value of the spike and half the minimum value of the dip.
In Figure 4A line P in the graph shows the loss to cladding modes in a fibre with a spike of radius 0.375 μm with increasing height of the spike. The radius of this spike constitutes approximately 9% of the fibre core which is 4 μm in radius. It is clear from this figure that losses to cladding modes are always less than 0.1 dB. Lines Q and R in Figure 3A are calculated for fibres with spikes of radii 0.50 μ and 0.625 μm, respectively. The radii of these spikes constitute approximately 12.5% and
16% of the 4 μm fibre core. Lines and R show that the loss to cladding modes can be substantial as the height of the spike increases
In Figure 4B line S in the graph shows the loss to cladding modes in a fibre with a dip of radius 0.25 μm with increasing depth of the dip. For the 4 μ radius fibre core in this case, the dip comprises approximately 6% of the core radius. It is clear from line S that the loss to cladding modes is minimal compared to lines T (dip radius
= 0.375 μ ) , U (dip radius = 0.5 μm) and V (dip radius = 0.625 μm) where the radius of the dip starts to increase and to become larger than 15% of the core radius. In particular line V in this figure is for a refractive index profile with depressed non-uniformity in the centre of the core where the width of the dip constitutes approximately 30% of the core radius. Line V shows that the loss to cladding modes can be substantial.
It is also observed that the relative height of the spike or the relative depth of the dip may play an important role in determining the overall fibre design parameters. Thus, the non-uniformity may be minimised and the photosensitivity may be maximised by reducing the amplitude of the dip or the spike as well as reducing the diameter.
A number of methods can be employed to vary the non- uniformity in the refractive index profile and, hence, the photosensitivity profile of the core. Two of these methods involve:
• Depositing a core and inner cladding with a larger number of layers. This increases the diameter of the core in the starting perform and reduces the relative effect of the refractive index (and hence the photosensitivity) variation in the centre of the core. This process may require additional overjacketing of the preform to obtain the correct core to cladding ratio.
• Modifying the chemical . composition of the gas flows during the collapsing process. By changing the relative flow rates of the gases flowing within the preform during the collapsing process and, possibly, adding additional gases, the chemical equilibrium within the collapsed region can be optimised to minimise any evaporation or change in composition of the deposited core material, for example by preventing Ge02 or Ge boil-off.
Optical fibres designed and fabricated as discussed above can reduce or eliminate cladding mode losses and so improve the range of applications of fibre Bragg gratings in telecommunication applications. These include, for example:
• Application for narrow-band devices. The presence of cladding mode losses limits the use of fibre Bragg gratings in add-drop filters as the cladding mode losses cause an unacceptable increase in the loss of other channels.
• Applications for broad-band, chirped gratings (e.g. for dispersion compensating and gain flattening) where the cladding mode losses introduce additional in-band losses which increase the insertion loss of the device.
Variations and modifications may be made in respect of the invention as above defined without departing from the scope of the invention as defined in the following statements of claims.
Claims
1. An optical fibre having a doped silica core and a silica cladding, wherein the core is formed throughout its cross-sectional area to minimise non-uniformity in the photosensitivity profile of the core.
2. An optical fibre as claimed in claim 1, wherein the core is formed such that the average diameter of the non- uniformity is not greater than 30% of the diameter of the core.
3. An optical fibre as claimed in claim 1, wherein the core is formed in a manner to reduce the amplitude of the non-uniformity in the photosensitivity profile.
. An optical fibre as claimed in any one of the preceding claims, wherein said non-uniformity comprises a central depression or spike.
5. An optical fibre as claimed in claim 4, wherein said central depression or spike has an average diameter or amplitude limited in size to reduce coupling into a cladding mode when a grating or other periodic structure is written into said fibre.
6. A method of forming an optical fibre, having the steps of:
(a) fabricating a preform by the modified chemical vapour deposition process, and
(b) drawing the fibre from the preform, wherein step (a) or step (b) or both steps (a) and (b) are performed in a manner to form a core which, throughout its cross-sectional area, exhibits a photosensitivity profile having a minimal non-uniformity.
7. A method as claimed in claim 6, wherein said non- uniformity comprises a central depression or spike.
8. A method as claimed in claim 5, including limiting the average diameter or amplitude of said central depression or spike in size to reduce coupling into a cladding mode when a grating or other periodic structure is written into said fibre.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2001278307A AU2001278307A1 (en) | 2000-08-11 | 2001-08-09 | Optical waveguide with minimised cladding mode coupling |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPQ9355A AUPQ935500A0 (en) | 2000-08-11 | 2000-08-11 | Optical waveguide with minimised cladding mode coupling |
| AUPQ9355 | 2000-08-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2002014918A1 true WO2002014918A1 (en) | 2002-02-21 |
Family
ID=3823413
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/AU2001/000976 WO2002014918A1 (en) | 2000-08-11 | 2001-08-09 | Optical waveguide with minimised cladding mode coupling |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AUPQ935500A0 (en) |
| WO (1) | WO2002014918A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109564326A (en) * | 2016-06-03 | 2019-04-02 | 洛克利光子有限公司 | Single mode waveguide with insulation bending section |
| US11681167B2 (en) | 2018-04-06 | 2023-06-20 | Rockley Photonics Limited | Optoelectronic device and array thereof |
| US11835762B2 (en) | 2021-03-05 | 2023-12-05 | Rockley Photonics Limited | Higher order mode filter |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2164642A (en) * | 1984-07-31 | 1986-03-26 | Furukawa Electric Co Ltd | Making optical fibre preforms |
| US4793843A (en) * | 1983-02-22 | 1988-12-27 | U.S. Philips Corporation | Method of manufacturing an optical fiber preform |
| GB2306955A (en) * | 1995-11-07 | 1997-05-14 | Samsung Electronics Co Ltd | Method of fabricating dispersion shifted optical fibre with smooth annular ring refractive index profile |
| US5852690A (en) * | 1997-06-30 | 1998-12-22 | Minnesota Mining And Manufacturing Company | Depressed cladding fiber design for reducing coupling to cladding modes in fiber gratings |
| US6009222A (en) * | 1997-09-12 | 1999-12-28 | Dong; Liang | Optical fibre and optical fibre grating |
| WO2001022136A1 (en) * | 1999-09-17 | 2001-03-29 | Corning Incorporated | Fiber bragg grating with cladding mode suppression |
-
2000
- 2000-08-11 AU AUPQ9355A patent/AUPQ935500A0/en not_active Abandoned
-
2001
- 2001-08-09 WO PCT/AU2001/000976 patent/WO2002014918A1/en active Application Filing
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4793843A (en) * | 1983-02-22 | 1988-12-27 | U.S. Philips Corporation | Method of manufacturing an optical fiber preform |
| GB2164642A (en) * | 1984-07-31 | 1986-03-26 | Furukawa Electric Co Ltd | Making optical fibre preforms |
| GB2306955A (en) * | 1995-11-07 | 1997-05-14 | Samsung Electronics Co Ltd | Method of fabricating dispersion shifted optical fibre with smooth annular ring refractive index profile |
| US5852690A (en) * | 1997-06-30 | 1998-12-22 | Minnesota Mining And Manufacturing Company | Depressed cladding fiber design for reducing coupling to cladding modes in fiber gratings |
| US6009222A (en) * | 1997-09-12 | 1999-12-28 | Dong; Liang | Optical fibre and optical fibre grating |
| WO2001022136A1 (en) * | 1999-09-17 | 2001-03-29 | Corning Incorporated | Fiber bragg grating with cladding mode suppression |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109564326A (en) * | 2016-06-03 | 2019-04-02 | 洛克利光子有限公司 | Single mode waveguide with insulation bending section |
| US10838146B2 (en) | 2016-06-03 | 2020-11-17 | Rockley Photonics Limited | Single mode waveguide with an adiabatic bend |
| US11681167B2 (en) | 2018-04-06 | 2023-06-20 | Rockley Photonics Limited | Optoelectronic device and array thereof |
| US11835762B2 (en) | 2021-03-05 | 2023-12-05 | Rockley Photonics Limited | Higher order mode filter |
Also Published As
| Publication number | Publication date |
|---|---|
| AUPQ935500A0 (en) | 2000-09-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6011886A (en) | Recoatable temperature-insensitive long-period gratings | |
| CA2565879C (en) | Long wavelength, pure silica core single mode fiber and method of forming the same | |
| US5883990A (en) | Low transmission loss optical fiber having a grating | |
| US6904215B2 (en) | Low macrobending loss optical fiber | |
| US6205279B1 (en) | Single mode optical fiber having multi-step core structure and method of fabricating the same | |
| JPH08234036A (en) | Single-mode optical waveguide fiber | |
| JP2007536580A5 (en) | ||
| WO2006046467A1 (en) | Optical fiber | |
| CA2360933A1 (en) | Distributed resonant ring fiber filter | |
| EP0126304B1 (en) | A single mode lightguide fiber having a trapezoidal refractive index profile | |
| JPH10501633A (en) | Optical waveguide | |
| RU2183027C2 (en) | Single-mode optical fiber | |
| KR20010022568A (en) | Dispersion managed optical waveguide fiber | |
| US6307994B1 (en) | Multi-cladding optical fiber, long-period optical fiber grating written therein and writing method thereof | |
| EP1240537A1 (en) | Fiber bragg grating with cladding mode suppression | |
| US6904213B2 (en) | Step index optical fiber with doped cladding and core, a preform, and a method of fabricating such a fiber | |
| US7603014B2 (en) | Method for the manufacture of optical fibers and improved optical fibers | |
| US7110651B2 (en) | Optical fiber having enhanced separation of higher-order modes | |
| US6728458B2 (en) | Optical fiber and fiber grating device | |
| WO2002014918A1 (en) | Optical waveguide with minimised cladding mode coupling | |
| EP1054274A1 (en) | Optical waveguide grating and method of manufacturing the same | |
| WO2000052507A1 (en) | Optical fiber | |
| EP1408354A1 (en) | Optical fiber with Bragg grating | |
| WO2002029459A1 (en) | Limited mode dispersion compensating optical fiber | |
| US20220196908A1 (en) | Optical fiber and optical fiber filter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AK | Designated states |
Kind code of ref document: A1 Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW |
|
| AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG |
|
| 121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
| REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
| 122 | Ep: pct application non-entry in european phase | ||
| NENP | Non-entry into the national phase |
Ref country code: JP |