CA1076858A - Low loss directional coupling for optical fibres - Google Patents
Low loss directional coupling for optical fibresInfo
- Publication number
- CA1076858A CA1076858A CA300,734A CA300734A CA1076858A CA 1076858 A CA1076858 A CA 1076858A CA 300734 A CA300734 A CA 300734A CA 1076858 A CA1076858 A CA 1076858A
- Authority
- CA
- Canada
- Prior art keywords
- fibre
- coupling
- turns
- tap
- ratio
- 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
- G02B6/26—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
-
- 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
- G02B6/245—Removing protective coverings of light guides before coupling
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Couplings Of Light Guides (AREA)
- Optical Communication System (AREA)
- Mechanical Coupling Of Light Guides (AREA)
Abstract
LOW LOSS DIRECTIONAL
COUPLING FOR OPTICAL FIBRES
Abstract of the Disclosure Low loss directional coupling of optical fibres is obtained by wrapping a tap fibre round a trunk fibre. Any cladding is first removed and then the tap fibre wrapped round the trunk fibre. The tap ratio can be varied by a variation in the number of turns or twists of the tap fibre around the trunk fibre. Signals can be abstracted by the tap fibre and also inserted.
- i -
COUPLING FOR OPTICAL FIBRES
Abstract of the Disclosure Low loss directional coupling of optical fibres is obtained by wrapping a tap fibre round a trunk fibre. Any cladding is first removed and then the tap fibre wrapped round the trunk fibre. The tap ratio can be varied by a variation in the number of turns or twists of the tap fibre around the trunk fibre. Signals can be abstracted by the tap fibre and also inserted.
- i -
Description
(~7 6~35~3 This invention relates to a low loss coupling for optical fibres, and particularly for coupling light into or out of a trunk fibre.
It is often necessary to couple a fibre to a trunk fibre and various arrangements exist, such as connecting the fibres . .
into dividers and the like. The o~jective is to obtain such coupling with the minimum of signal loss. Also, conventional couplers have to be individually designed, depending upon the desired ratio between the continuing trunk signal and the coupled ~-out signal. The various arrangements are often complex and require careful and accurate manufacture and assembly.
The present invention provides an extremely simple and readily variable coupling of a fibre to a further fibre, with a very low signal loss The tap fibre is wrapped round the trunk ~ `
fibre, after removal of the claddi~g from the section of both fibres ~
::
to be wrapped The tap ratio, that is the ratio between the trunk fibre output relative to the tap fibre output, and also the ratio between the trunk fibre input and the tap fibre input, can be varied considerably. ~ ~-The invention will be readily understood by the following description in conjunction with the accompanying drawings, ~ -in which:-Figure 1 is a diagrammatic illustration of a coupling arrangement for coupling light out;
Figure 2 is a diagrammatic illustration of a coupling arrangement for coupling light in;
Figure 3 is a diagrammatic illustration of a coupling arrangement for coupling light out for monitoring the signal in the trunkj Figure 4 is a curve illustrating the relationship : ' - ' '':
1~76~58 between tap ratio and n~mber of t~ists of the tap fibre around the main fibre;
Figure S illustrates the output from the two parts of a coupling.
As illustrated in figure 1, a main or trunk fibre is indicated at 10, with a light emitting diode (LED~ or laser input device at 11 and a detector at 12. A tap fibre is indicated at 13, with the twists of the tap Fibre around the main fibre indicated at 14. A detector is indicated at 15 for the tap fibre 13. In the particular example, fibres 10 and 13 have a silica core and a silicone cladding - typical material being that sold under the trademark Supra Sil-l for the core and GE 670 for the cladding. To make the coupling, first the silicone cladding was stripped off a section (whose length depended on the tap ratio desired~ of both the trunk fibre and the tap fibre. This can be done with metal strippers and it can also be done chemically by heating in tetramethylguanidine for 1 hour at 100C. The stripped -section of the tap fibre was then t~isted around that of the trunk fibre. No fusing or heating was required. Over 30 splices were ,20 made with a varying number of twists. Some of the splices were protected by re-covering them again in silicone. ;
Figure 2 illustrates an arrangement for coupling in ~-t to the trunk fibre 10. The fibre inserting the signal is indicated at 16 with its input device at 18, the wrap turns indicated at 17.
The losses for the arrangement of figure 2 will be somewhat higher than for the arrangement of figure 1, as some light will propagate right through fibre 16 and issue at 18. It is possible to use the output at 18 to monitor the signal in the trunk fibre by a detector 18a, Figure 3 illustrates the use of a coupling out tap at 19 to proYide a monitoring signal at 20. By applying the ;
coupling near the input device 11, there is Yery little loss at the detector 12, as those modes and the leaky wavelengths which are rapidly lost in a normal trunk fibre, will be abstracted by the coupling 19. ;
Other forms of fibre than the silica core/silicone cladding can be used, for one or other, or both fibres, that is ~
trunk fibre and tap fibre. Thus silica core/silica clad fibres, ~;
usually with a plastic coating, can be used. The plastic coating is first removed, as by burning~ and then the silica cladding etched away.
Figure 4 shows a curve of tap ratio versus the number of twists for an arrangement as in figure 1. The length of the coupling section varied approximately lincarly with the number of twists. All the couplings were made with about two t~ists per inch. The tap ratio - A/B - is the ratio of the continuing signal, or output signal, in the trunk fibre tA~ ~ `
related to the signal in the tap fibre (B~. -A most important parameter in determining the loss of the coupling is the cleanliness of the fibre surfaces after stripping the silicone. Light lost because of surface contamination -can be almost totally regained by proper cleaning. The loss for couplings as in figure 1 was found to be approximately 0.1 dB or -less. Protecting the coupling by re-covering with silicone has little or no effect on the tap ratio or the loss.
Figure 5 shows a picture of the output from the two ports of a t~pical coupling (tap ratio of ~2.5:1) as in figure 1, when the light source was a HeNe laser focussed through a 45X
microscope lens into the fibre, the ports being the output ends of 30- the fibres 10 and 13.
107~358 The actual pitch of the t~ists of the tap fibre depends upon the flexibility of the tap fibre, ~hich in turn depends upon the material of the fibre, and its diameter. Some materials are rnuch more Flexible tllan others and it ~as been proposed to use synthetic plastic material for the core of optical fibres. The diameter of the main fibre 10 will also have an influence upon the pitch of the twists. The cladding material can, of course, vary also.
The method of coupling light into or out from a main or trunk fibre has the advantages of simplicity, low loss, and having a controllable and wide range of tap ratio.
::
~ .
.. ~ .
It is often necessary to couple a fibre to a trunk fibre and various arrangements exist, such as connecting the fibres . .
into dividers and the like. The o~jective is to obtain such coupling with the minimum of signal loss. Also, conventional couplers have to be individually designed, depending upon the desired ratio between the continuing trunk signal and the coupled ~-out signal. The various arrangements are often complex and require careful and accurate manufacture and assembly.
The present invention provides an extremely simple and readily variable coupling of a fibre to a further fibre, with a very low signal loss The tap fibre is wrapped round the trunk ~ `
fibre, after removal of the claddi~g from the section of both fibres ~
::
to be wrapped The tap ratio, that is the ratio between the trunk fibre output relative to the tap fibre output, and also the ratio between the trunk fibre input and the tap fibre input, can be varied considerably. ~ ~-The invention will be readily understood by the following description in conjunction with the accompanying drawings, ~ -in which:-Figure 1 is a diagrammatic illustration of a coupling arrangement for coupling light out;
Figure 2 is a diagrammatic illustration of a coupling arrangement for coupling light in;
Figure 3 is a diagrammatic illustration of a coupling arrangement for coupling light out for monitoring the signal in the trunkj Figure 4 is a curve illustrating the relationship : ' - ' '':
1~76~58 between tap ratio and n~mber of t~ists of the tap fibre around the main fibre;
Figure S illustrates the output from the two parts of a coupling.
As illustrated in figure 1, a main or trunk fibre is indicated at 10, with a light emitting diode (LED~ or laser input device at 11 and a detector at 12. A tap fibre is indicated at 13, with the twists of the tap Fibre around the main fibre indicated at 14. A detector is indicated at 15 for the tap fibre 13. In the particular example, fibres 10 and 13 have a silica core and a silicone cladding - typical material being that sold under the trademark Supra Sil-l for the core and GE 670 for the cladding. To make the coupling, first the silicone cladding was stripped off a section (whose length depended on the tap ratio desired~ of both the trunk fibre and the tap fibre. This can be done with metal strippers and it can also be done chemically by heating in tetramethylguanidine for 1 hour at 100C. The stripped -section of the tap fibre was then t~isted around that of the trunk fibre. No fusing or heating was required. Over 30 splices were ,20 made with a varying number of twists. Some of the splices were protected by re-covering them again in silicone. ;
Figure 2 illustrates an arrangement for coupling in ~-t to the trunk fibre 10. The fibre inserting the signal is indicated at 16 with its input device at 18, the wrap turns indicated at 17.
The losses for the arrangement of figure 2 will be somewhat higher than for the arrangement of figure 1, as some light will propagate right through fibre 16 and issue at 18. It is possible to use the output at 18 to monitor the signal in the trunk fibre by a detector 18a, Figure 3 illustrates the use of a coupling out tap at 19 to proYide a monitoring signal at 20. By applying the ;
coupling near the input device 11, there is Yery little loss at the detector 12, as those modes and the leaky wavelengths which are rapidly lost in a normal trunk fibre, will be abstracted by the coupling 19. ;
Other forms of fibre than the silica core/silicone cladding can be used, for one or other, or both fibres, that is ~
trunk fibre and tap fibre. Thus silica core/silica clad fibres, ~;
usually with a plastic coating, can be used. The plastic coating is first removed, as by burning~ and then the silica cladding etched away.
Figure 4 shows a curve of tap ratio versus the number of twists for an arrangement as in figure 1. The length of the coupling section varied approximately lincarly with the number of twists. All the couplings were made with about two t~ists per inch. The tap ratio - A/B - is the ratio of the continuing signal, or output signal, in the trunk fibre tA~ ~ `
related to the signal in the tap fibre (B~. -A most important parameter in determining the loss of the coupling is the cleanliness of the fibre surfaces after stripping the silicone. Light lost because of surface contamination -can be almost totally regained by proper cleaning. The loss for couplings as in figure 1 was found to be approximately 0.1 dB or -less. Protecting the coupling by re-covering with silicone has little or no effect on the tap ratio or the loss.
Figure 5 shows a picture of the output from the two ports of a t~pical coupling (tap ratio of ~2.5:1) as in figure 1, when the light source was a HeNe laser focussed through a 45X
microscope lens into the fibre, the ports being the output ends of 30- the fibres 10 and 13.
107~358 The actual pitch of the t~ists of the tap fibre depends upon the flexibility of the tap fibre, ~hich in turn depends upon the material of the fibre, and its diameter. Some materials are rnuch more Flexible tllan others and it ~as been proposed to use synthetic plastic material for the core of optical fibres. The diameter of the main fibre 10 will also have an influence upon the pitch of the twists. The cladding material can, of course, vary also.
The method of coupling light into or out from a main or trunk fibre has the advantages of simplicity, low loss, and having a controllable and wide range of tap ratio.
::
~ .
.. ~ .
Claims (10)
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:-
1. A low loss directional coupling for optical fibres comprising a first fibre and a second fibre, the second fibre wrapped round the first fibre a predetermined number of turns, any cladding layer on the fibres removed whereby the light transmitting cores of the fibres are in contact.
2. A coupling as claimed in claim 1, for coupling light into the first fibre, and including a light emitting device at an input end of the second fibre.
3. A coupling as claimed in claim 2, including a monitoring device at an output end of the second fibre.
4. A coupling as claimed in claim 1, for coupling light out of the first fibre, including a detector at an output end of the second fibre.
5. A coupling as claimed in claim 1, for monitoring a signal in the first fibre, including a monitoring device at an output end of the second fibre.
6. A coupling as claimed in claim 4, the number of wrapped turns of the second fibres varied in dependence on the desired ratio between the output of the first fibre and the output of the second fibre, the number of turns increased for a decrease in said ratio.
7. A coupling as claimed in claim 2, the number of wrapped turns of the second fibre varied in dependence on the desired ratio between the input of the first fibre and the input of the second fibre, the number of turns increased for a decrease in said ratio.
8. A method of directionally coupling a first optical fibre to a second optical fibre, comprising removing any cladding layer from a portion of each fibre and wrapping said portion of said second fibre round said portion of said first fibre for a predetermined number of turns.
9. A method as claimed in claim 8, for coupling light into said first fibre, including varying the number of wrapped turns to vary the ratio between the input of the first fibre and the input of the second fibre.
10. A method as claimed in claim 8, for coupling light out of said first fibre, including varying the number of wrapped turns to vary the ratio between the output of the second fibre.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA300,734A CA1076858A (en) | 1978-04-10 | 1978-04-10 | Low loss directional coupling for optical fibres |
| BE0/194400A BE875316A (en) | 1978-04-10 | 1979-04-04 | LOW-LOSS DIRECTIONAL COUPLING FOR OPTICAL FIBERS |
| DE19792913794 DE2913794A1 (en) | 1978-04-10 | 1979-04-05 | COUPLING ARRANGEMENT FOR OPTICAL FIBERS |
| FR7908850A FR2422972A1 (en) | 1978-04-10 | 1979-04-06 | LOW-LOSS DIRECTIONAL COUPLING FOR OPTICAL FIBERS |
| JP4213079A JPS54145154A (en) | 1978-04-10 | 1979-04-09 | Lowwloss directional coupling for optical fibers |
| GB7912561A GB2018460B (en) | 1978-04-10 | 1979-04-10 | Directional coupling for optical fibres |
| JP1982142700U JPS5893911U (en) | 1978-04-10 | 1982-09-22 | Low-loss directional coupling for fiber optics |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA300,734A CA1076858A (en) | 1978-04-10 | 1978-04-10 | Low loss directional coupling for optical fibres |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1076858A true CA1076858A (en) | 1980-05-06 |
Family
ID=4111190
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA300,734A Expired CA1076858A (en) | 1978-04-10 | 1978-04-10 | Low loss directional coupling for optical fibres |
Country Status (6)
| Country | Link |
|---|---|
| JP (2) | JPS54145154A (en) |
| BE (1) | BE875316A (en) |
| CA (1) | CA1076858A (en) |
| DE (1) | DE2913794A1 (en) |
| FR (1) | FR2422972A1 (en) |
| GB (1) | GB2018460B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5830703A (en) * | 1981-08-17 | 1983-02-23 | Sumitomo Electric Ind Ltd | Fiber having silicone resin clad for optical communication |
| US4802723A (en) * | 1982-09-09 | 1989-02-07 | American Telephone And Telegraph Company, At&T Bell Laboratories | Optical fiber tap |
| GB2191597B (en) * | 1986-02-21 | 1989-11-15 | Plessey Co Plc | Interwined monomode fibre-optic coupler. |
| DE4030068C2 (en) * | 1990-09-22 | 1994-04-14 | Deutsche Aerospace | Device for coupling out light |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4843947A (en) * | 1971-10-08 | 1973-06-25 | ||
| GB1470539A (en) * | 1974-06-06 | 1977-04-14 | Standard Telephones Cables Ltd | Optical fibre optical power dividers |
| NL7513127A (en) * | 1974-11-11 | 1976-05-13 | Western Electric Co | DEVICE FOR TAPING OPTICAL POWER FROM AN INTERMEDIATE SECTION OF A FIBEROPTIC WAVE GUIDE. |
| DE2456619A1 (en) * | 1974-11-29 | 1976-08-12 | Siemens Ag | ARRANGEMENT OF BRANCHES ON MESSAGE TRANSMISSION LINES WITH OPTICAL FIBERS |
| CH607066A5 (en) * | 1975-12-05 | 1978-11-30 | Comp Generale Electricite | |
| GB1493660A (en) * | 1975-12-16 | 1977-11-30 | Standard Telephones Cables Ltd | Optical waveguide power dividers |
| JPS5283237A (en) * | 1975-12-30 | 1977-07-12 | Fujikura Ltd | Shunt connection of plastic-cladding optical fibers |
| US4083625A (en) * | 1976-08-02 | 1978-04-11 | Corning Glass Works | Optical fiber junction device |
| DE2922022A1 (en) * | 1979-05-30 | 1980-12-11 | Wmf Wuerttemberg Metallwaren | COFFEE MACHINE |
-
1978
- 1978-04-10 CA CA300,734A patent/CA1076858A/en not_active Expired
-
1979
- 1979-04-04 BE BE0/194400A patent/BE875316A/en unknown
- 1979-04-05 DE DE19792913794 patent/DE2913794A1/en active Granted
- 1979-04-06 FR FR7908850A patent/FR2422972A1/en not_active Withdrawn
- 1979-04-09 JP JP4213079A patent/JPS54145154A/en active Pending
- 1979-04-10 GB GB7912561A patent/GB2018460B/en not_active Expired
-
1982
- 1982-09-22 JP JP1982142700U patent/JPS5893911U/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS54145154A (en) | 1979-11-13 |
| DE2913794C2 (en) | 1990-04-26 |
| GB2018460A (en) | 1979-10-17 |
| GB2018460B (en) | 1982-06-23 |
| FR2422972A1 (en) | 1979-11-09 |
| DE2913794A1 (en) | 1979-10-18 |
| JPS5893911U (en) | 1983-06-25 |
| BE875316A (en) | 1979-10-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |