GB2136985A - Fabricating couplers in optical fibres by fusing - Google Patents
Fabricating couplers in optical fibres by fusing Download PDFInfo
- Publication number
- GB2136985A GB2136985A GB08406274A GB8406274A GB2136985A GB 2136985 A GB2136985 A GB 2136985A GB 08406274 A GB08406274 A GB 08406274A GB 8406274 A GB8406274 A GB 8406274A GB 2136985 A GB2136985 A GB 2136985A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fibre
- fabricating
- fibres
- coupler
- coupling region
- 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
- G02B6/24—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
- G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
- G02B6/2821—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers using lateral coupling between contiguous fibres to split or combine optical signals
- G02B6/2835—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers using lateral coupling between contiguous fibres to split or combine optical signals formed or shaped by thermal treatment, e.g. couplers
Abstract
A method of fabricating couplers in optical fibres, for example two fibres (5, 6) forming an X coupler, involves traversing a flame along the coupling region (7) of the fibres in an oscillatory motion and simultaneously stretching and twisting the fibres to give a symmetrical and smooth biconical taper. The oscillatory motion is performed in such a way that the part of the fibres at the ends of the oscillatory stroke do not become hotter than that part at the centre of the stroke and so either the speed of the flame increases, or the flame moves away from the fibre, towards the ends of the stroke. <IMAGE>
Description
SPECIFICATION
Fabricating couplers in fibres
This invention relates to couplers for optical fibres and particularly to a method of fabricating such couplers.
Various different types of couplers between fibres are known and one coupler which gives a very low loss is the fused biconical coupler such as that described in "Low loss access coupler such as that described in "Low loss access coupler for
multimode optical fibre distribution networks"
B. S. Kawasaki and K. O. Hill in "Applied Optics"
Vol. 16 No. 7, July 1977, or U.S. Patent No.
4291940.
In this example two fibres each consisting of a central core, a cladding layer surrounding the core and a protective coating, usually of plastics, have their coatings completely removed, in the region where coupling is to take place, and are laid
longitudinally side by side and slightly twisted. An oxy-butane flame is applied so that the fibres start to fuse together and simultaneously they are stretched to give a symmetrical taper. By controlling the geometry of the taper, the amount of power coupled between the fibres can be fixed, the overall loss of the coupler being dependent mainly on the symmetry and smoothness of the taper.
This form of coupling has low loss but is difficult to fabricate reliably because even the smallest distortion of the core of a fibre, invisible under a low powered microscope, can cause a dramatic loss of power. Monomode fibres are particularly susceptible to this. These distortions can easily occur while the fibre is being heated in the way described above. The fibres have little rigidity and when they are heated they soften and so become still weaker. They bend and twist to relax any stresses that might be present and. in particular they tend to be blown away by the flow of gases in the flame. In addition to the main gas flow there can be a lot of turbulence which may also cause distortion of the fibre.
In order to lessen these effects the gas flow has been reduced to a minimum, the orifice of the torch has been reduced and flow controllers have been introduced into the oxygen and butane gas supplies. However, with a much smaller flame the fibres are obviously heated over a shorter length and the resulting taper is very sharp which can lead to a high loss in the coupler. Couplers can -also be constructed by forming a taper in a single fibre by the above technique, but this suffers from the same drawback.
According to one aspect, the invention provides a method of fabricating a coupler in at least one optical fibre comprising the steps of, traversing a flame along the coupling region of the fibre(s) in an oscillatory motion in such a way that the parts of the fibre(s) at either end of the oscillatory stroke do not become hotter than the part of the fibre(s) at the centre of the stroke, and simultaneously stretching the fibre(s) to give a symmetrical and smooth biconical taper in the or each fibre.
The invention also provides apparatus for
fabricating a coupler in at least one optical fibre,
comprising a pair of support blocks each having a
longitudinal groove for supporting the fibre(s) such
that the fibre coupling region is situated between
said blocks, a pair of moving tables for clamping
the part of the fibre(s) remote from the coupling
region and movable away from said support
blocks for stretching said fibre(s), a burner
arranged to be supplied with a combustible gas or
gas mixture to provide a flame for heating the fibre(s) at the coupling region, and means for traversing said burner, in use along the coupling
region in an oscillatory motion such that it is
moving faster at either end of its oscillatory stroke than at the centre of said stroke.
Preferably the period of oscillation is sufficiently short so that the fibre retains an almost constant temperature profile.
The oscillatory motion may be linear or it may be angular and is preferably produced by a cam but programmed stepping motors or free running motors continuously switched by microswitches may also be used.
One way of carrying out the method according to the invention will now be described as used on two fibres in the fabrication of an X coupler, with reference to the drawing in which:
Figure 1 shows one example of a cam profile for controlling the oscillatory motion of the torch;
Figure 2 shows a schematic view of the coupler, and
Figure 3 shows a schematic diagram of apparatus used to form the coupler.
The two fibres 5 and 6 are first stripped of their coating, in the region 7 where the coupler is to be formed, and are then laid longitudinally side by side and slightly twisted within a wedge-shaped groove in support blocks 1 and 2 as shown in
Figure 3. They are lightly clamped, so that they are able to move longitudinally. The blocks are inclined about the longitudinal groove direction at about 1 5O to the horizontal each in the opposite sense to provide the twist to keep the fibres together. Both ends of the fibres are clamped on a respective moving table 3 and 4 each of which tables is connected to a mechanism for stretching the fibres in a smooth and controlled fashion, for example by means of a clamp connected to a micrometer screw.An oxy-butane flame which is as small as practicable is now directed on the twisted region of the fibres from a micro-torch 8 which is supplied from a gas supply 19 via a pipe 18 and which is mounted on a carriage 13 running on linear bearings 1 4 between two end blocks 1 5 and 16, in an oscillatory motion as shown by arrow 9 so that the flame is traversed along the fibre so that the fibres fuse together and the micrometer screws are simultaneously turned to stretch the fibres and form the coupler as shown in Figure 2.As shown in Figure 3, movement of the torch is effected by means of a rotating cam 10 designed such that its cam follower 1 1, mounted on an extension 12 of the carriage 1 3 and biased against the cam 10 by a spring 17, passes over the points of minimum and maximum radius, corresponding to the position of the flame at the ends of the stroke, as fast as possible, but causes the flame to pass relatively slowly over the midpoint region. A cam shaped as in Fig. 1 with a radius variation of 12 mm to 1 6 mm giving a stroke along the fibre or fibres of 4 mm was found most successful, but any cam shape which gives the desired effect can be used.
The torch may be traversed linearly along the fibres under the control of the cam, although it can alternatively be oscillated in an angular fashion to cause the flame to move along the length of the fibres in the described manner and away from them towards the end of the stroke.
The couplers may then be strain relieved by bonding to a glass or silica substrate and then encapsulated in a silicone resin, such as Sylgard 184.
This technique can also be used on a single fibre for producing a biconical taper so that signals may be tapped off at the taper, or on several fibres to couple them together. It is applicable to all fibre types, except plastic fibres.
Claims (15)
1. A method of fabricating a coupler in at least one optical fibre, comprising the steps of traversing a flame along the coupling region of the fibre(s) in an oscillatory motion in such a way that the parts of the fibre(s) at either end of the oscillatory stroke do not become hotter than the part of the fibre(s) at the centre of the stroke, and simultaneously stretching the fibre(s) to give a symmetrical and smooth biconical taper in the fibre(s).
2. A method of fabricating a coupler according to Claim 1 wherein the coupler is made in two or more optical fibres and the fibres are slightly twisted prior to traversing a flame along the coupling region.
3. A method of fabricating a coupler according to any one of Claims 1 or 2 wherein said flame is provided by a micro-torch.
4. A method of fabricating a coupler according to any preceding Claim in which the or each said fibre is provided with a protective coating, wherein the coating or coatings is/are first stripped from the fibre or fibres in the coupling region.
5. A method of fabricating a coupler according to any preceding Claim wherein the period of oscillation is sufficiently short that the fibre(s) retains an almost constant temperature profile in the coupling region.
6. A method of fabricating a coupler according to any preceding Claim wherein the oscillatory motion is linear.
7. A method of fabricating a coupler according to any one of Claims 1-5 wherein the oscillatory motion is angular.
8. A method of fabricating a coupler according to any preceding Claim wherein the oscillatory motion is produced by a cam.
9. A method of fabricating a coupler according to any preceding Claim wherein the coupling region of the or each fibre is subsequently bonded to a substrate and encapsulated in a silicone resin.
10. Apparatus for fabricating a couler in at least one optical fibre, comprising a pair of support blocks each having a longitudinal groove for supporting the fibre(s) such that the fibre coupling region is situated between said blocks, a pair of moving tables for clamping the part of the fibre(s) remote from the coupling region and movable away from said support blocks for stretching said fibre(s), a burner arranged to be supplied with a combustible gas or gas mixture to provide a flame for heating the fibre(s) at the coupling region, and means for traversing said burner, in use along the coupling region in an oscillatory motion such that it is moving faster at either end of its oscillatory stroke than at the centre of said stroke.
1 Apparatus for fabricating a coupler according to Claim 10 wherein said support blocks are inclined to the horizontal about the longitudinal groove direction, each in the opposite sense, so as to provide, when in use for fabricating a coupler in two or more fibres, a twist to the fibres.
12. Apparatus for fabricating a coupler according to any one of Claims 10 or 11 wherein said means for traversing said burner comprises a cam and cam follower shaped to provide the said oscillating motion.
1 3. Apparatus according to Claim 12 wherein the burner is mounted on a carriage member to slidably supported for linear movement on guide means, and the cam acts on a cam follower carried by the carriage member.
14. Apparatus for fabricating a coupler substantially as hereinbefore described with reference to Figures 1 and 3 of the drawings.
15. A method of fabricating a coupler substantially as hereinbefore described with reference to Figures 2 and 3 of the drawings.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08406274A GB2136985B (en) | 1983-03-22 | 1984-03-09 | Fabricating couplers in optical fibres by fusing |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB838307850A GB8307850D0 (en) | 1983-03-22 | 1983-03-22 | Fabricating couplers in fibres |
GB08406274A GB2136985B (en) | 1983-03-22 | 1984-03-09 | Fabricating couplers in optical fibres by fusing |
Publications (3)
Publication Number | Publication Date |
---|---|
GB8406274D0 GB8406274D0 (en) | 1984-04-11 |
GB2136985A true GB2136985A (en) | 1984-09-26 |
GB2136985B GB2136985B (en) | 1986-09-10 |
Family
ID=26285582
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB08406274A Expired GB2136985B (en) | 1983-03-22 | 1984-03-09 | Fabricating couplers in optical fibres by fusing |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2136985B (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2199423A (en) * | 1986-12-05 | 1988-07-06 | Conleth Denis Hussey | Fibre optic transfer devices |
FR2618228A1 (en) * | 1987-07-18 | 1989-01-20 | Stc Plc | METHOD AND APPARATUS FOR LOADING FIBER OPTIC CABLES. |
GB2217473A (en) * | 1988-04-14 | 1989-10-25 | Bicc Plc | Fused optical fibre coupler manufacture |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1484207A (en) * | 1975-01-23 | 1977-09-01 | Standard Telephones Cables Ltd | Optical fibre optical power dividers |
EP0018768A1 (en) * | 1979-05-01 | 1980-11-12 | BRITISH TELECOMMUNICATIONS public limited company | Apparatus of joining together optical fibres |
GB1600324A (en) * | 1977-06-13 | 1981-10-14 | Canadian Patents Dev | Low loss access coupler for multimode optical fibre distribution systems |
GB2112165A (en) * | 1981-10-07 | 1983-07-13 | Int Standard Electric Corp | Fused biconical fibre optic coupler |
-
1984
- 1984-03-09 GB GB08406274A patent/GB2136985B/en not_active Expired
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1484207A (en) * | 1975-01-23 | 1977-09-01 | Standard Telephones Cables Ltd | Optical fibre optical power dividers |
GB1600324A (en) * | 1977-06-13 | 1981-10-14 | Canadian Patents Dev | Low loss access coupler for multimode optical fibre distribution systems |
EP0018768A1 (en) * | 1979-05-01 | 1980-11-12 | BRITISH TELECOMMUNICATIONS public limited company | Apparatus of joining together optical fibres |
GB2112165A (en) * | 1981-10-07 | 1983-07-13 | Int Standard Electric Corp | Fused biconical fibre optic coupler |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2199423A (en) * | 1986-12-05 | 1988-07-06 | Conleth Denis Hussey | Fibre optic transfer devices |
GB2199423B (en) * | 1986-12-05 | 1991-04-17 | Conleth Denis Hussey | Fibre optic components |
FR2618228A1 (en) * | 1987-07-18 | 1989-01-20 | Stc Plc | METHOD AND APPARATUS FOR LOADING FIBER OPTIC CABLES. |
GB2207255A (en) * | 1987-07-18 | 1989-01-25 | Stc Plc | Removing optical fibre encapsulation with hot gas jet |
GB2207255B (en) * | 1987-07-18 | 1991-03-20 | Stc Plc | Removing optical fibre encapsulation with a heated gas jet |
GB2217473A (en) * | 1988-04-14 | 1989-10-25 | Bicc Plc | Fused optical fibre coupler manufacture |
GB2217473B (en) * | 1988-04-14 | 1992-02-19 | Bicc Plc | Optical fibre coupler manufacture |
Also Published As
Publication number | Publication date |
---|---|
GB2136985B (en) | 1986-09-10 |
GB8406274D0 (en) | 1984-04-11 |
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Legal Events
Date | Code | Title | Description |
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PCNP | Patent ceased through non-payment of renewal fee |