GB2100464A - An improved optical fibre - Google Patents
An improved optical fibre Download PDFInfo
- Publication number
- GB2100464A GB2100464A GB8213235A GB8213235A GB2100464A GB 2100464 A GB2100464 A GB 2100464A GB 8213235 A GB8213235 A GB 8213235A GB 8213235 A GB8213235 A GB 8213235A GB 2100464 A GB2100464 A GB 2100464A
- Authority
- GB
- United Kingdom
- Prior art keywords
- core
- barrier layer
- fluorine
- base glass
- bearing compound
- 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.)
- Granted
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
- G02B6/03616—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
- G02B6/03638—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 3 layers only
- G02B6/03655—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 3 layers only arranged - + +
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C13/00—Fibre or filament compositions
- C03C13/04—Fibre optics, e.g. core and clad fibre compositions
- C03C13/045—Silica-containing oxide glass compositions
-
- 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
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
- G02B6/0281—Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core
-
- 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 - +
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Glass Compositions (AREA)
Abstract
A graded index optical fibre in which a fluorine-bearing compound is used as a refractive index depressing dopant in both the barrier layer and the core of the fibre to compensate for the sudden introduction of GeO2 at the barrier-core interface. The sudden increase in the value of the refractive index from the barrier layer to the core is therefore removed by the presence of the fluorine-bearing compound, thereby increasing the bandwidth of the fibre.
Description
SPECIFICATION
An improved optical fibre
This invention relates to optical fibres suitable for use in optical cables for use in the communications field adapted fortransmission of light. More particularly, the invention is concerned with optical fibres of composite form comprising a core of glass or other transparent material clad throughout its length with another transparent material of lower refractive index.
it is the general practice to form composite optical fibres from preforms or blanks manufactured by a known process referred to as the inside vapour phase oxidation process. In this known process, a barrier layer is deposited on the inner surface of a support or substrate tube prior to deposition on the inner surface of the tube of the glass that is to constitute the core of the preform, the substrate tube constituting the cladding. The barrier layer serves to reduce interface scattering and absorption losses by removing the core/cladding interface which would otherwise exist between deposited layers of high purity, low attenuation glasses and the inner surface of the substrate tube.
With a view to increasing substantially the information bandwidth of composite optical fibre formed from such a preform, during manufacture ofthe preform it is known to arrange that the refractive index of the core increases smoothly and continuously towards the core axis over at least a part of the distance between the outer surface of the core and the core axis; such a composition optical fibre is generally, and hereinafter will be, referred to as a "graded index optical fibre". The information bandwidth of graded index optical fibre can be from about 10 to more than 102 times greater than the bandwidth of a composite optical fibre with a core having an ungraded index profile. The increase in information bandwidth is very dependent on the shape of the index of refraction profile, the favoured profile currently being approximately parabolic.
It has been recognised that, where there is a sudden increase in the value of the refractive index from the barrier layer to the core at the interface between the barrier layer and the core of a graded index optical fibre, undesirable pulse spreading of higher order modes is caused resulting in a reduction in bandwith of the fibre and forms of graded index optical fibre have been proposed in which the presence of such a sudden increase is eliminated. Such optical fibres have a cladding of a base glass essentially silica which may contain dopants and a barrier layer of a base glass and at least one dopant (such as boron) which reduces the index of refraction, the barrier layer having an index of refraction which is substantially constantthroughoutthe radial thickness of the barrier layer and which is equal to or less than that of the cladding.This sudden increase in the refractive index is due to the introduction of a fresh vapour in the vapour phase oxidation process as one of the dopants for the core, or the sudden cessation of a barrier layer dopant.
It is an object of the present invention to provide an improved graded index optical fibre which does not have this sudden increase in the refractive index.
According to the invention the improved graded index optical fibre comprises an outer cladding layer having a predetermined index of refraction, a barrier layer on the inner wall surface of the cladding layer, and a core disposed within and adhering to, the barrier layer, wherein the barrier layer consists essentially of a base glass containing a fluorine-bearing compound and P205, the relative quantities of the fluorine-bearing compound and P205 throu ghout the radial thickness of the barrier layer being such that the barrier layer has an index of refraction which is substantially constant throughout the radial thickness of the barrier layer and which is equal to or less than the index of refraction of the cladding layer, and the core consists essentially of a base glass containing a fluorine-bearing compound, P205 and GeO2, the quantity of fluorine-bearing compound in the base glass of the core decreasing smoothly and continuously towards the core axis, the quantity of P205 in the base glass of the core being substantially constant or increasing smoothly and continuously towards the core axis, the quantity of GeO2 in the base glass of the core increasing smoothly and con tinuouslytowards the core axis, and the quantities of fluorine-bearing compound, P205 and GeO2 in the base glass of the core at the interface between the core and the barrier layer being such that, at that interface, the index of refraction of the core is equal to or less than that of the barrier layer.
Compensation for a sudden change of refractive index such as is caused by the sudden introduction of GeO2 at the barrier-core interface may be effected if a fluorine-bearing compound is present in both barrier and core, by altering the quantity of fluorine-bearing compound when the interface is reached. This arrangement is undesirable where boron is a dopant in the base glass of the barrier layer (instead of the fluorine-bearing compound) as the presence of boron in the core decreases the effi ciency of the core in transmitting light.
To compensate for the sudden introduction of
GeO2 in the base glass of the core, the quantity of P2O5 in the base glass of the core at the interface between the core and the barrier layer may be correspondingly reduced to be less than the quantity of P205 in the base glass of the barrier layer, or the quantity of fluorine-bearing compound in the base glass of the core at the interface may be raised to more than the quantity of fluorine-bearing compound in the base glass of the barrier layer.
Preferably, also, the quantity of fluorine-bearing compound in the base glass of the core decreases smoothly in a direction towards the core axis either linearly or in a curve that may be parabolic in such a way that, at the core axis, the quantity of fluorinebearing compound is substantially zero. The fluorine-bearing compound will contain no hyd
rogen and, as the fluorine-bearing compound, it is
preferred to employ dichlorodifluoro methane as the
vapour in the vapour phase oxidation process to
form the fluorine-bearing compound.
Preferably, at the interface between the barrier
layer and the core, the quantity of fiuorine-bearing
compound is a maximum value and the quantity of the GeO2 is a minimum value and, at the axis of the
core, the quantity of fluorine-bearing compound is substantially zero and the quantity of GeO2 is a max
imum value.
Preferably, the base glass of the barrier layer also includes, throughout its radial thickness, a quantity of GeO2. In this case the quantities of fluorinebearing compound, P205 and GeO2 in the base glass ofthe core at the interface between the core and the barrier layer may be substantially equal to the quantities of fluorine-bearing compound, P205 and GeO2 in the base glass of the barrier layer.
Preferably, the quantities of fluorine-bearing compound, P205 and, when present, GeO2 in the base glass ofthe barrier layer are substantially constant throughout the radial thickness of the barrier layer.
This invention also includes a method of making a graded index optical fibre by the vapour phase oxidation process, said method comprising introducing in gas or vapour form at leastSiCl4, 02, POCI2 and a fluorine-bearing element into a support or substrate tube (which forms the outer cladding layer) to form the barrier layer on the inner surface of the tube, and then introducing in gasorvapourform atleastSiCl4, 02, GeCI4 and a fluorine-bearing element to form the core, the rate of flow of the POC13, GeCI4 and fluorine-bearing element being controlled such that at the interface between the core and the barrier layer the refractive index of the core is equal to or less than that of the barrier layer, and such that the refractive index of the core increases smoothly and continuously towards the core axis over at least a part of the distance between the outer surface of the core and the core axis.
The fluorine-bearing element is preferably dichloro-difluoro methane.
GeCI4 is preferably also introduced as a gas or vapour during the formation of the barrier layer.
The invention is further illustrated by a description, by way of example, of preferred forms of the improved graded index optical fibre with reference to the accompaying diagrammatic drawings, in which: Figure 1 is an isometric view of the improved graded index optical fibre;
Figures 2,3 and 4 are graphical illustrations of the relative quantities of components introduced by source vapour materials to form preferred forms of the improved graded index optical fibre, and
Figures 5 to 7 are graphical illustrations of preferred forms of the improved graded index optical fibre.
The graded index optical fibre shown in Figure 1 comprises an outer cladding 1 having a predeter
mined index of refraction, a barrier layer 2 on the
inner wall surface of the cladding layer, and a core 3 disposed within and adhering to the barrier layer.
The barrier layer 2 consists of a base glass contain
ing a fluorine-bearing compound, and P205, and, if
desired, a quantity of GeO2. As shown in Figures 2, 3
and 4, the relative quantities of the fluorine-bearing compound, P205 and, when present, GeO2 in the
base glass of the barrier layer 2 are substantially constant throughout the radial thickness of the bar
rier layer 2, to ensurethatthe index of refraction is substantially constant throughout the radial thickness of the barrier layer The index of refraction of the barrier layer may be equal to, or less than, the index of refraction of the cladding layer 1, as shown in Figure 5, and Figures 6 and 7, respectively.
The core 3 consists of a glass comprising a base glass containing a fluorine-bearing compound, P205, and GeO2. As shown in Figures 2,3 and 4 the relative quantities of the fluorine-bearing compound, P205 and GeO2 vary smoothly and continuously throughout the radial thickness of the core, to ensure that the indext of refraction of the core decreases parabolically from the core axis to the interface with the barrier layer 2. At the interface, the index of refraction of the core 3 may be equal to, or less than, the index of refraction of the barrier layer 2, as shown in Figures 5 and 6, and Figure 7, respectively.
As will be seen on referring to Figure 2, to compensate for the presence of GeO2 in the base glass of the core 3, the quantity of P205 in the base glass of the core at the interface between the core and the barrier layer 2 is substantially less than the quantity of P205 in the base glass of the barrier layer.
Alternatively, it will be seen on referring to Figure 3, to compensate for the presence of GeO2 in the base glass of the core 3, the quantity of fluorinebearing compound in the base glass of the core at the interface is substantially more than the quantity of fluorine-bearing compound in the base glass of the barrier layer 2.
The quantity of fluorine-bearing compound in the base glass of the core 3 decreases smoothly in a direction towards the core axis either linearly, as shown in Figures 2 and 3, or in a curve that may be parabolic, as shown in Figure 5, in such a way that, at the core axis, the quantity of fluorine-bearing compound is substantially zero.
The base glass of the barrier layer 2 may also include, throughout its radial thickness, a quantity of
GeO2 and, as shown in Figure 4, in this case the quantities of fluorine-bearing compound, P205 and
GeO2 in the base glass of the core 3 atthe interface between the core and the barrier layer are substantially equal to the quantities of fluorine-bearing compound, P205 and GeO2 in the base glass ofthe barrier layer.
The absence of boron in the base glass of the core 3 has the important advantage that Rayteigh scattering is substantially reduced and the infra-red absorption of the B-O vibrational bands in the spectral range between 1.2 and 1.5 micrometres is also absent
Claims (11)
1. A graded index optical fibre comprises an outer cladding layer having a predetermined index of refraction, a barrier layer on the inner wall surface of the cladding layer, and a core disposed within and adhering to, the barrier layer, wherein the barrier layer consists essentially of a base glass containing a fluorine-bearing compound and P205, the relative quantities of the fluorine-bearing compound and P205 throughout the radial thickness of the barrier layer being such that the barrier layer has an index of refraction which is substantially constant throughout the radial thickness of the barrier layer and which is equal to or less than the index of refraction of the cladding layer, and the core consists essentially of a base glass containing a fluorine-bearing compound, P2O5 and GeO2, the quantity of fluorine-bearing compound in the base glass of the core decreasing smoothly and continuously towards the core axis, the quantity of P205 in the base glass of the core being substantially constant or increasing smoothly and continuously towards the core axis, the quantity of GeOz in the base glass of the core increasing smoothly and continuously towards the core axis, and the quantities of fluorine-bearing compound, P205 and GeO2 in the base glass of the core at the interface between the core and the barrier layer being such that, at that interface, the index of refraction of the core is equal to or less than that of the barrier layer.
2. A graded index optical fibre as claimed in
Claim 1, wherein at the interface between the barrier layer and the core, the quantity of the fluorinebearing compound is a maximum value and the quantity of GeO2 is a minimum value and, at the axis of the core, the quantity of the fluorine-bearing compound is substantially zero and the quantity of GeO2 is a maximum value.
3. A graded index optical fibre as claimed in
Claim 1 or Claim 2, wherein the quantity of P205 in the base glass of the core at the interface between the core and the barrier layer is correspondingly reduced to be less than the quantity of P2Os in the base glass of the barrier layer.
4. A graded index optical fibre as claimed in any one of the preceding Claims, wherein the quantity of fluorine-bearing compound in the base glass of the core at the interface is raised to more than the quantity of fluorine-bearing compound in the base glass of the barrier layer.
5. A graded index optical fibre as claimed in any one of the preceding Claims, wherein the barrier layer also includes throughout its radial thickness, a quantity of GeO2.
6. A graded index optical fibre as claimed in
Claim 5, wherein the quantities offluorine-bearing compound, P205 and GeO2 in the base glass of the core at the interface between the core and the barrier layer are substantially equal to the quantities of fluorine-bearing compound, P205 and GeO2 in the base glass of the barrier layer.
7. A graded index optical fibre as claimed in any one of the preceding Claims, wherein the quantity of fluorine-bearing compound in the base glass of the core decreases smoothly in a direction towards the core axis in such a way that, at the core axis, the quantity of fluorine-bearing compound is substantially zero.
8. A graded index optical fibre as claimed in
Claim 7, wherein the quantity of fluorine-bearing compound in the base glass of the core decreases smoothly in a direction towards the core axis in a curve that is parabolic.
9. A graded index optical fibre as claimed in any one of the preceding Claims, wherein the quantities of fluorine-bearing compound, P205 and, when pres ent, GeO2 in the base glass of the barrier layer are substantially constant throughout the radial thickness of the barrier layer.
10. A graded index optical fibre substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
11. A method of making a graded index optical fibre as claimed in any one of Claims 1 to 10, as hereinbefore described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8213235A GB2100464B (en) | 1981-05-11 | 1982-05-07 | An improved optical fibre |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8114261 | 1981-05-11 | ||
| GB8213235A GB2100464B (en) | 1981-05-11 | 1982-05-07 | An improved optical fibre |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2100464A true GB2100464A (en) | 1982-12-22 |
| GB2100464B GB2100464B (en) | 1985-07-17 |
Family
ID=26279404
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8213235A Expired GB2100464B (en) | 1981-05-11 | 1982-05-07 | An improved optical fibre |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2100464B (en) |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0083843A2 (en) * | 1981-12-07 | 1983-07-20 | Corning Glass Works | Low dispersion, low-loss single-mode optical waveguide |
| EP0127408A1 (en) * | 1983-05-20 | 1984-12-05 | Corning Glass Works | Optical waveguide fiber |
| EP0191202A2 (en) * | 1985-01-11 | 1986-08-20 | Philips Patentverwaltung GmbH | Optical fibres doped with fluorine and process for their production |
| FR2679548A1 (en) * | 1991-07-25 | 1993-01-29 | Alsthom Cge Alcatel | PROCESS FOR PRODUCING ACTIVE OPTICAL FIBERS. |
| US5210816A (en) * | 1991-06-24 | 1993-05-11 | The Furukawa Electric Co., Ltd. | Optical fiber and process of producing same |
| EP1498753A2 (en) * | 2003-07-18 | 2005-01-19 | Fujikura Ltd. | Graded-index multimode fiber and manufacturing method therefor |
| US20110305423A1 (en) * | 2007-10-23 | 2011-12-15 | Draka Comteq B.V. | Multimode Fiber |
| NL2005220C2 (en) * | 2010-08-12 | 2012-02-14 | Draka Comteq Bv | Depressed graded index multi-mode optical fiber. |
| US8542967B2 (en) | 2010-08-12 | 2013-09-24 | Draka Comteq, B.V. | Depressed graded index multi-mode optical fiber |
| US9014525B2 (en) | 2009-09-09 | 2015-04-21 | Draka Comteq, B.V. | Trench-assisted multimode optical fiber |
| CN106062599A (en) * | 2014-02-28 | 2016-10-26 | 德拉克通信科技公司 | Multimode optical fiber with high bandwidth over an extended wavelength range, and corresponding multimode optical system |
-
1982
- 1982-05-07 GB GB8213235A patent/GB2100464B/en not_active Expired
Cited By (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0083843A2 (en) * | 1981-12-07 | 1983-07-20 | Corning Glass Works | Low dispersion, low-loss single-mode optical waveguide |
| EP0083843A3 (en) * | 1981-12-07 | 1984-01-04 | Corning Glass Works | Low dispersion, low-loss single-mode optical waveguide |
| EP0127408A1 (en) * | 1983-05-20 | 1984-12-05 | Corning Glass Works | Optical waveguide fiber |
| EP0191202A2 (en) * | 1985-01-11 | 1986-08-20 | Philips Patentverwaltung GmbH | Optical fibres doped with fluorine and process for their production |
| EP0191202A3 (en) * | 1985-01-11 | 1988-06-01 | Philips Patentverwaltung Gmbh | Optical fibres doped with fluorine and process for their production |
| US5210816A (en) * | 1991-06-24 | 1993-05-11 | The Furukawa Electric Co., Ltd. | Optical fiber and process of producing same |
| FR2679548A1 (en) * | 1991-07-25 | 1993-01-29 | Alsthom Cge Alcatel | PROCESS FOR PRODUCING ACTIVE OPTICAL FIBERS. |
| US5364429A (en) * | 1991-07-25 | 1994-11-15 | Alcatel Fibres Optiques | Method of manufacturing active optical fibers |
| EP1498753A2 (en) * | 2003-07-18 | 2005-01-19 | Fujikura Ltd. | Graded-index multimode fiber and manufacturing method therefor |
| EP1498753A3 (en) * | 2003-07-18 | 2005-02-16 | Fujikura Ltd. | Graded-index multimode fiber and manufacturing method therefor |
| US7043126B2 (en) | 2003-07-18 | 2006-05-09 | Fujikura Ltd. | Graded-index multimode fiber and manufacturing method therefor |
| US20110305423A1 (en) * | 2007-10-23 | 2011-12-15 | Draka Comteq B.V. | Multimode Fiber |
| US8724950B2 (en) * | 2007-10-23 | 2014-05-13 | Draka Comteq, B.V. | Multimode fiber |
| KR101554373B1 (en) | 2007-10-23 | 2015-09-18 | 드라카 콤텍 비.브이. | Multimode fiber |
| US9014525B2 (en) | 2009-09-09 | 2015-04-21 | Draka Comteq, B.V. | Trench-assisted multimode optical fiber |
| NL2005220C2 (en) * | 2010-08-12 | 2012-02-14 | Draka Comteq Bv | Depressed graded index multi-mode optical fiber. |
| US8542967B2 (en) | 2010-08-12 | 2013-09-24 | Draka Comteq, B.V. | Depressed graded index multi-mode optical fiber |
| CN106062599A (en) * | 2014-02-28 | 2016-10-26 | 德拉克通信科技公司 | Multimode optical fiber with high bandwidth over an extended wavelength range, and corresponding multimode optical system |
| CN106062599B (en) * | 2014-02-28 | 2019-05-28 | 德拉克通信科技公司 | With the multimode fibre and corresponding multimode optical system of high bandwidth in the wave-length coverage of extension |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2100464B (en) | 1985-07-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |