GB2189048A - Determining alignment in optical fibre fusion splicing - Google Patents

Determining alignment in optical fibre fusion splicing Download PDF

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Publication number
GB2189048A
GB2189048A GB08707876A GB8707876A GB2189048A GB 2189048 A GB2189048 A GB 2189048A GB 08707876 A GB08707876 A GB 08707876A GB 8707876 A GB8707876 A GB 8707876A GB 2189048 A GB2189048 A GB 2189048A
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United Kingdom
Prior art keywords
optical fibres
optical
light
end faces
optical fibre
Prior art date
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Granted
Application number
GB08707876A
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GB8707876D0 (en
GB2189048B (en
Inventor
Louis Peter Lou
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Balfour Beatty PLC
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BICC PLC
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Filing date
Publication date
Application filed by BICC PLC filed Critical BICC PLC
Publication of GB8707876D0 publication Critical patent/GB8707876D0/en
Publication of GB2189048A publication Critical patent/GB2189048A/en
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Publication of GB2189048B publication Critical patent/GB2189048B/en
Expired legal-status Critical Current

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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
    • G02B6/255—Splicing of light guides, e.g. by fusion or bonding
    • G02B6/2555—Alignment or adjustment devices for aligning prior to splicing
    • 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
    • G02B6/255—Splicing of light guides, e.g. by fusion or bonding
    • G02B6/2551—Splicing of light guides, e.g. by fusion or bonding using thermal methods, e.g. fusion welding by arc discharge, laser beam, plasma torch

Abstract

A method of determining when the end faces of two optical fibres 1, 11 abut comprises arranging the two optical fibres in approximately axial alignment and with their end faces 4, 14 spaced apart, causing one of the fibres 1 to oscillate transversely of its axis with respect to the other 11 and causing it to move in a direction towards the other optical fibre, and monitoring the approaching optical fibres to determine the position at which there is substantially no relative transverse movement between the two optical fibres, at which position their end faces will be abutting. Preferably, light is injected into the core of one of the optical fibres 1 and the intensity of light which is transferred into the core of the other optical fibre 11 and which oscillates between maximum and minimum values due to the relative transverse movement is monitored to determine the position at which the intensity of the transferred light is constant, thereby indicating that there is no relative transverse movement between the two optical fibres and that their end faces are abutting. <IMAGE>

Description

SPECIFICATION Optical fibre splicing This invention relates to effecting a permanent end-to-end fusion splice between two optical fibres, one or each of which may be a component of an optical cable.
In effecting a fusion splice between two optical fibres, before the two optical fibres are fused together it is necessary to ensure, not only that the cores of the optical fibres are axially aligned for optimum transfer of light from one fibre to the other, but also that the end faces of the optical fibres abut without undue pressure between them so as to provide for a satisfactory fusion splice to be made. Hitherto, although automatic methods have been devised for effecting axial alignment of the cores of two optical fibres, satisfactory abutting of the end faces of the aligned fibres has depended upon the expertise of the operator, using purely visual means.
It is an objective of the present invention to provide, in effecting a permanent end-to-end fusion splice between two optical fibres, an improved method of determining when the end faces of said two optical fibres are abutting, which method can be readily employed with optical fibres of all kinds and types currently available.
According to the invention, the improved method comprises arranging the two optical fibres with their axes in approximately axial alignment and with their neighbouring end faces spaced apart; causing at least one of said optical fibres to oscillate transversely of its axis with respect to the other optical fibre and causing the or each optical fibre to move in a direction towards the other optical fibre; and monitoring the approaching optical fibres to determine the position at which there is substantially no relative transverse movement between the two optical fibres, at which position their end faces will be abutting.
Preferably, one of the two optical fibres is maintained stationary and serves as a datum and the other of the two optical fibres is caused to oscillate transversely with respect to its axis and is moved towards the stationary optical fibre.
By way of example, satisfactory results have been obtained by causing one of the optical fibres to oscillate a few microns on each side of its longitudinal axis as the optical fibre is caused to move towards the other optical fibre.
The approaching optical fibres may be monitored to determine the position at which there is substantially relative transverse movement between them by means of the naked eye or by means of image analysis techniques but, for convenience, in one preferred method light is injected into the core of one of the optical fibres and the intensity of light which is transferred into the core of the other optical fibre and which oscillates between maximum and minimum values due to the relative transverse movement between the cores of the optical fibres is monitored to determine the position at which the intensity of the transferred light is substantially constant, thereby indicating that there is substantially no relative transverse movement between the two optical fibres and that their end faces are abutting.In this case, preferably light is injected at a position adjacent the proposed fusion splice between the two optical fibres and the intensity of light transferred into the core of the other optical fibre is monitored by detecting a signal produced by light extracted from the core of the other optical fibre at a position in the other optical fibre adjacent the proposed splice.
In an alternative preferred method, light is directed into the gap between the neighbouring ends of the approaching optical fibres and the intensity of light entering the core of at least one of the optical fibres is monitored to determine the position at which said light intensity, which gradually diminishes as the length of the gap between the approaching optical fibres is closed and that their end faces are abutting.
Where light is injected into the core of one of the optical fibres, light from a supplementary source may be directed between the neighbouring ends of the two optical fibres so that, while there is a gap between them, an amount of the supplementary light depending on the length of the gap enters the core of the other optical fibre and is seen as noise detected by the monitor and recognisable by the modulation, when the signal from the supplementary light reaches substantially zero serving to indicate that the end faces of the two optical fibre are abutting. Such supplementary light is useful in resolving special cases such as chance symmetry of transverse oscillation of one optical fibre with respect to the other which would be viewed as zero relative oscillation and would lead to a false indication of butting.In such circumstances, the signal from the supplementary light would indicate that a gap still exists between the neighbouring ends of the two optical fibres and the transverse oscillatory movement of one of the optical fibres can be biassed so that perfect symmetry is no longer present and the method of determining when the end faces of the optical fibres abut can be successfully concluded.
Although each of these preferred methods of the invention can be manually controlled, it is preferred for each to be effected automatically.
In all cases, before effecting a fusion splice, preferably the positions of the optical fibres at which their end faces abut is recorded, one or each optical fibre is moved in a lengthwise direction away from the other optical fibre and accurate axial alignment of the cores of the optical fibres is effected automatically; the spaced end faces of the optical fibres are prefused to clean them; the or each optical fibre is returned to its recorded position, in which recorded position the end faces of the optical fibres abut and the axes of their cores will now be in accurate axial alignment; and fusion splicing of the abutting, aligned optical fibres is then effected.
The invention also includes improved apparatus for determining when the neighbouring end faces of two optical fibres are abutting by the improved method hereinbefore described.
The invention is further illustrated by a description, by way of example, of a method of effecting a permanent end-to-end fusion splice between two optical fibres in which a preferred method of determining when the end faces of the two optical fibres are abutting is employed, with reference to the accompanying diagrammatic drawing, in which: Figure 1 is a diagrammatic view of an initial stage of the fusion splicing method, and Figure 2 is an intermediate stage of the method.
Referring to Fig. 1, the two optical fibres 1,11 between which a permanent end-to-end fusion splice is to be effected are arranged with their axes in approximately axial alignment and with their neighbouring end faces 4,14 spaced apart. Optical fibre 11 is maintained stationary and serves as a datum and optical fibre 1 is caused to oscillate transversely a few microns on each side of its longitudinal axis and is moved towards the stationary optical fibre in the direction of arrow B.To determine the position at which there is substantially no relative transverse movement between the two optical fibres 1,11, at which position their end faces 4,14 will be abutting, light is injected into the core 2 of the optical fibre 1 at a position adjacent the proposed fusion splice between the two optical fibres and the intensity of light transferred into the core 12 of the other optical fibre 11 is monitored by detecting a signal 5 produced by light extracted from the core 12 at a position adjacent the proposed splice.
The signal 5 oscillates between maximum and minimum values due to the relative transverse movement between the cores 2,12 of the approaching optical fibres 1,11.
Axial movement of the optical fibre 1 in the direction of arrow B continues until, as shown in Fig. 2, the intensity of the transferred light indicated by signal 5 becomes substantially constant, thereby indicating that there is now no relative transverse movement between the two optical fibres 1,11 and that their end faces 4,14 are abutting. The positions of the - optical fibres 1,11 at which their end faces, 4,14 abut is recorded and each optical fibre is then moved in an axial direction away from the other optical fibre and accurate axial alignment of the cores 2,12 of the optical fibres is effected automatically using any known technique. The spaced end faces 4,14 of the optical fibres 1,11 are then pre-fused to clean them and the optical fibres are returned to their recorded positions, in which recorded positions the end faces of the optical fibres abut and the axes of the cores 2,12 will now be in accurate axial alignment. The abutting, aligned optical fibres 1,11 are then fusion spliced.

Claims (11)

1. In effecting an end-to end fusion splice between two optical fibres, a method of determining when the end faces of said two optical fibres are abutting which comprises arranging the two optical fibres with their axes in approximately axial alignment and with their neighbouring end faces spaced apart; causing at least one of said optical fibres to oscillate transversely of its axis with respect to the other optical fibre and causing the or each optical fibre to move in a direction towards the other optical fibre; and monitoring the approaching optical fibres to determine the position at which there is substantially no relative transverse movement between the two optical fibres, at which position their end faces will be abutting.
2. A method as claimed in Claim 1, wherein one of the two optical fibres is maintained stationary and serves as a datum and the other of the two optical fibres is caused to oscillate transversely with respect to its axis and is moved towards the stationary optical fibre.
3. A method as claimed in Claim 1 or 2, wherein monitoring the approaching optical fibres to determine the position at which there is substantially no relative transverse movement between them is effected by injecting light into the core of one of the optical fibres and by monitoring the intensity of light which is transferred into the core of the other optical fibre and which oscillates between maximum and minimum values due to the relative transverse movement between the cores of the optical fibres to determine the position at which the intensity of the transferred light is substantially constant, thereby indicating that there is substantially no relative transverse movement between the two optical fibres and their end faces are abutting.
4. A method as claimed in Claim 3, wherein light is injected into said optical fibre at position adjacent the proposed optical fibre splice and the intensity of light transferred into the core of the other optical fibre is monitored by detecting a signal produced by light extracted from the core of the other optical fibre at a position in the other optical fibre adjacent the proposed splice.
5. A method as claimed in Claim 1 or 2, wherein monitoring the approaching optical fibres to determine the position at which there is substantially no relative transverse movement between them is effected by directing light into the gap between the neighbouring ends of the approaching optical fibres and by monitoring the intensity of light entering the core of at least one of the optical fibres to determine the position at which said light intensity, which gradually diminishes as the length of the gap decreases, reaches substantially zero, thereby indicating that the gap between the approaching optical fibres is closed and that their end faces are abutting.
6. A method as claimed in Claim 1 or 2, wherein monitoring the approaching optical fibres to determine the position at which there is substantially no relative transverse movement between them is effected by injecting light into the core of one of the optical fibres and monitoring the intensity of light which is transferred into the core of the other optical fibre and which oscillates between maximum and minimum values due to the relative transverse movement between the cores of the optical fibres to determine the position at which the intensity of the transferred light is substantially constant, thereby indicating that there is substantially no relative transverse movement between the two optical fibres and, at the same time, by directing light from a supplementary source between the neighbouring ends of the two optical fibres so that, while there is a gap between them, an amount of the supplementary light depending upon the length of the gap enters the core of said other optical fibre and is seen as noise detected by the monitor and recognisable by the moduiation, when the signal from the supplementary light reaches substantially zero serving to indicate that the end faces of the two optical fibres are abutting.
7. A method as claimed in any one of Claims 3 to 6, wherein the steps of the method are effected automatically.
8. A method as claimed in any one of the preceding Claims, wherein, before effecting the fusion splice between the abutting optical fibres, the positions of the optical fibres at which their end faces abut is recorded; one or each optical fibre is moved in a lengthwise direction away from the other optical fibre and accurate axial alignment of the cores of the optical fibres is effected automatically; the spaced end faces of the optical fibres are prefused to clean them; the or each optical fibre is returned to its recorded position, in which recorded positions the end faces of the optical fibres abut and the axes of their cores will now be in accurate axial alignment; and fusion splicing of the abutting, aligned optical fibres is then effected.
9. A method as claimed in Claim 1 or 2, wherein monitoring the approaching optical fibres to determine the position at which there is substantially no relative transverse movement between them is effected by an image analysis technique.
10. In effecting an end-to-end fusion splice between two optical fibres, a method of determining when the end faces of said two optical fibres are abutting substantially as hereinbefore described with reference to the accompanying drawing.
11. Apparatus for determining when the neighbouring end faces of two optical fibres are abutting by the method claimed in any one of the preceding Claims.
GB8707876A 1986-04-04 1987-04-02 Optical fibre alignment in fusion splicing Expired GB2189048B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB868608282A GB8608282D0 (en) 1986-04-04 1986-04-04 Optical fibre splicing

Publications (3)

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GB8707876D0 GB8707876D0 (en) 1987-05-07
GB2189048A true GB2189048A (en) 1987-10-14
GB2189048B GB2189048B (en) 1989-11-29

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GB868608282A Pending GB8608282D0 (en) 1986-04-04 1986-04-04 Optical fibre splicing
GB8707876A Expired GB2189048B (en) 1986-04-04 1987-04-02 Optical fibre alignment in fusion splicing

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GB868608282A Pending GB8608282D0 (en) 1986-04-04 1986-04-04 Optical fibre splicing

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2254935A (en) * 1991-04-03 1992-10-21 Bicc Plc Optical fibre fusion splicing apparatus
GB2271433A (en) * 1992-10-08 1994-04-13 David Lister Myers Optical fibre fusion splicing with reciprocal movement
GB2272306A (en) * 1992-11-09 1994-05-11 Fujitsu Ltd Coupling optical waveguides by fusion or photosensitive monomer-polymer compositions
US5902715A (en) * 1992-11-09 1999-05-11 Fujitsu Limited Method of forming a mirror in a waveguide

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0130944A2 (en) * 1983-06-24 1985-01-09 Fondation Suisse Pour La Recherche En Microtechnique Method of aligning an optical fibre

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0130944A2 (en) * 1983-06-24 1985-01-09 Fondation Suisse Pour La Recherche En Microtechnique Method of aligning an optical fibre

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2254935A (en) * 1991-04-03 1992-10-21 Bicc Plc Optical fibre fusion splicing apparatus
US5249247A (en) * 1991-04-03 1993-09-28 Bicc Plc Optical fibre splicing device
GB2254935B (en) * 1991-04-03 1994-06-29 Bicc Plc Optical fibre splicing
GB2271433A (en) * 1992-10-08 1994-04-13 David Lister Myers Optical fibre fusion splicing with reciprocal movement
GB2272306A (en) * 1992-11-09 1994-05-11 Fujitsu Ltd Coupling optical waveguides by fusion or photosensitive monomer-polymer compositions
GB2272306B (en) * 1992-11-09 1996-11-20 Fujitsu Ltd Coupling of optical parts using a refractive index imaging material
US5581646A (en) * 1992-11-09 1996-12-03 Fujitsu Limited Method of coupling optical parts and refractive index imaging material
US5658966A (en) * 1992-11-09 1997-08-19 Fujitsu Limited Method of coupling optical parts and refractive index imaging material
US5861444A (en) * 1992-11-09 1999-01-19 Fujitsu Limited Refractive index imaging material
US5902715A (en) * 1992-11-09 1999-05-11 Fujitsu Limited Method of forming a mirror in a waveguide
US6017681A (en) * 1992-11-09 2000-01-25 Fujitsu Limited Method of coupling optical parts and method of forming a mirror

Also Published As

Publication number Publication date
GB8707876D0 (en) 1987-05-07
GB2189048B (en) 1989-11-29
GB8608282D0 (en) 1986-05-08

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930402