GB2298287A - Bragg reflective grating creation in optical fibres - Google Patents

Bragg reflective grating creation in optical fibres Download PDF

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Publication number
GB2298287A
GB2298287A GB9503861A GB9503861A GB2298287A GB 2298287 A GB2298287 A GB 2298287A GB 9503861 A GB9503861 A GB 9503861A GB 9503861 A GB9503861 A GB 9503861A GB 2298287 A GB2298287 A GB 2298287A
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United Kingdom
Prior art keywords
fibre
grating
bragg reflective
reflective grating
optical fibres
Prior art date
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Granted
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GB9503861A
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GB2298287B (en
GB9503861D0 (en
Inventor
Stephen Ross Baker
Richard Edward Epworth
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Nortel Networks Ltd
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Northern Telecom Ltd
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Priority to GB9503861A priority Critical patent/GB2298287B/en
Publication of GB9503861D0 publication Critical patent/GB9503861D0/en
Publication of GB2298287A publication Critical patent/GB2298287A/en
Application granted granted Critical
Publication of GB2298287B publication Critical patent/GB2298287B/en
Anticipated expiration legal-status Critical
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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02Optical fibres with cladding with or without a coating
    • G02B6/02057Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076Refractive index modulation gratings, e.g. Bragg gratings
    • G02B6/02123Refractive index modulation gratings, e.g. Bragg gratings characterised by the method of manufacture of the grating
    • G02B6/02133Refractive index modulation gratings, e.g. Bragg gratings characterised by the method of manufacture of the grating using beam interference
    • G02B6/02138Refractive index modulation gratings, e.g. Bragg gratings characterised by the method of manufacture of the grating using beam interference based on illuminating a phase mask
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02Optical fibres with cladding with or without a coating
    • G02B6/02057Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076Refractive index modulation gratings, e.g. Bragg gratings
    • G02B6/02123Refractive index modulation gratings, e.g. Bragg gratings characterised by the method of manufacture of the grating
    • G02B6/02152Refractive index modulation gratings, e.g. Bragg gratings characterised by the method of manufacture of the grating involving moving the fibre or a manufacturing element, stretching of the fibre

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)

Abstract

A Bragg reflective grating with improved circular symmetry is generated in a length 11 of optical fibre by rotating the fibre about its axis while the grating is being created by lateral irradiation. The fibre 11 may be held between two chucks 12 of a precision lathes that are synchronously driven. Shown are argon ion laser 13, telescope 14, aperture 15, mirror 16, stepper drive 18, cylindrical lens 17 and phase grating 10.

Description

Bragg Reflective Grating Creation in Fibres This invention relates to the creation of Bragg reflective gratings in optical fibres by lateral irradiation. Such gratings find application for instance in wavelength division multiplexed optical transmission systems where they may be used for instance for channel dropping and for channel insertion. It is generally desirable in such systems to minimise unnecessary system losses.
It is known that the lateral irradiation of an optical fibre with a fringe pattern of relatively intense ultra-violet light can be used to generate a Bragg reflective grating in such a fibre.
Such a fringe pattern can be provided by two-beam interference effects, for in stance as described in United States Patent No 4 275 110. An alternative way of providing such a fringe pattern can be with the aid of a phase grating, as for instance described in a paper by K O Hill et al entitled, ' Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask', Appl. Phys. Lett., Vol. 2, No. 10, pp 1035-7.
Particularly in the case of creating Bragg reflective gratings that are designed to be retro-reflective so that light propagating in the fibre towards the grating, and reflected by that grating, shall be reflected to propagate in the reverse direction, it has been found that these methods of grating creation can lead to non-uniformities in the resulting grating that are attributable to the absorption of the irradiating light by the fibre as that irradiating light propagates through the fibre. In consequence the 'strength' of the grating is not maximised and coupling of power into cladding modes may result, this giving rise to a short wavelength loss edge. Additionally birefringence will be introduced.
The present invention is directed to the alleviating of non-uniformities resulting from this cause.
According to the present invention there is provided a method of creating a Bragg reflective grating in an optical fibre by lateral irradiation of the fibre, wherein, during said lateral irradiation, relative rotational movement about the fibre axis is provided between the irradiated portion of the fibre and the irradiation.
This relative movement is effective in alleviating the non-uniformity to which previous reference has been made by making the completed grating substantially circularly symmetric.
Generally it is found more convenient to provide the requisite relative movement by rotating the irradiated portion of fibre rather than the fringe pattern. When it is the irradiated portion of the fibre that is rotated, this may be achieved by rotating both ends of the fibre in synchronism so that the whole fibre is rotated about its axis, or by twisting the fibre by rotating only one end while the other end is clamped.
One way of creating the grating is by illuminating the fibre from the side with an interferometrically generated fringe pattern of UV light generated using two-beam interferometry. Another way employs a localised fringe pattern generated in the vicinity of a different grating, typically a phase grating.
There follows a description of the creation of a Bragg reflective grating in an optical fibre by a method embodying the invention in a preferred form. The description refers to the accompanying drawing in which is a schematic diagram of the apparatus employed to create the grating.
The writing of the Bragg reflection grating was effected using a diffraction grating. In this instance the diffraction grating took the form of a phase grating (phase contrast diffraction grating). This grating was created in a plasma enhanced chemical vapour deposited silica layer deposited upon a silica substrate. For this purpose the deposited silica layer was coated with a layer of chromium that was itself created with a layer of electron beam lithography resist. A grating 50mm in length was created in the chromium layer by electron beam lithography. With the particular equipment employed it was not found possible to scan the electron beam over the full 50mm without incurring significant distortions or discontinuities, to the linear scan, and so a mechanical step and repeat procedure was employed to create the full length of grating in sections.Such mechanical stepping can itself introduce large discontinuities but precautions were taken to reduce this to minimal levels by careful attention to the calibration of the electron beam scan field and correction of scan distortions after the manner set out by C Dix et al., "High accuracy electron-beam grating lithography for optical and optoelectronic devices J. Vac. Sci. Technol. B, 1992, 10(6), pp 2662.
The electron beam lithography resist was patterned and developed to provide an etch mask for the underlying chromium layer. Then the chrome layer was etched to provide a mask for the silica layer that underlied it, and finally the chromium mask layer was etched away to leave the required phase grating, which is depicted at 10 in the accompanying drawing.
To use this phase grating to create a Bragg reflection grating in a length 11 of single mode optical fibre according to a method embodying the present invention in a preferred form, the phase grating 10 is located almost in contact with fibre 11 with the grating lines extending transversely of the fibre axis, preferably at right angles to that axis. The fibre 11 is held between two chucks 12 of a precision lathe (not shown) that are synchronously driven. An argon ion laser 13 providing a frequency doubled ultraviolet light output has this output directed on to the phase grating 10 via a telescope 14, and aperture 15, a mirror 16, and a cylindrical lens 17. The mirror 16 is attached to a stepper drive 18 by means of which the mirror can be translated in a controlled manner in the axial direction of the fibre 11 so as to track the light beam across the phase grating 10 in the axial direction of the fibre 11 while that fibre is rotated about its axis by the chucks 12.

Claims (1)

  1. CLAIM:
    1. A method of creating a Bragg reflective grating in an optical fibre by lateral irradiation of the fibre, wherein, during said lateral irradiation, relative rotational movement about the fibre axis is provided between the irradiated portion of the fibre and the irradiation.
GB9503861A 1995-02-25 1995-02-25 Bragg reflective grating creation in fibres Expired - Fee Related GB2298287B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9503861A GB2298287B (en) 1995-02-25 1995-02-25 Bragg reflective grating creation in fibres

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9503861A GB2298287B (en) 1995-02-25 1995-02-25 Bragg reflective grating creation in fibres

Publications (3)

Publication Number Publication Date
GB9503861D0 GB9503861D0 (en) 1995-04-19
GB2298287A true GB2298287A (en) 1996-08-28
GB2298287B GB2298287B (en) 1998-05-06

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GB (1) GB2298287B (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
WO1999045417A1 (en) * 1998-03-02 1999-09-10 Uniphase Fibre Components Pty. Limited Grating writing method and apparatus
GB2352531A (en) * 1999-07-28 2001-01-31 Samsung Electronics Co Ltd Apparatus for manufacturing fibre optic gratings by rotating optic fibre
GB2375830A (en) * 2001-05-22 2002-11-27 Marconi Caswell Ltd Creating Bragg gratings in optical waveguide devices
EP1345050A4 (en) * 2000-11-28 2005-10-12 Fujikura Ltd Method and device for manufacturing optical fiber grating, optical fiber grating, optical module, and optical communication system
EP1717612A1 (en) * 2005-04-26 2006-11-02 Harris Corporation Apparatus and method for forming an optical microresonator

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2189901A (en) * 1986-04-25 1987-11-04 Stc Plc Laser-induced fibre grating devices

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2189901A (en) * 1986-04-25 1987-11-04 Stc Plc Laser-induced fibre grating devices

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
WO1999045417A1 (en) * 1998-03-02 1999-09-10 Uniphase Fibre Components Pty. Limited Grating writing method and apparatus
US6434300B1 (en) 1998-03-02 2002-08-13 Jds Uniphase Pty. Ltd. Grating writing method and apparatus
GB2352531A (en) * 1999-07-28 2001-01-31 Samsung Electronics Co Ltd Apparatus for manufacturing fibre optic gratings by rotating optic fibre
GB2352531B (en) * 1999-07-28 2002-09-25 Samsung Electronics Co Ltd A method of manufacturing long period fibre gratings
EP1345050A4 (en) * 2000-11-28 2005-10-12 Fujikura Ltd Method and device for manufacturing optical fiber grating, optical fiber grating, optical module, and optical communication system
EP1760501A1 (en) 2000-11-28 2007-03-07 Fujikura Ltd. Optical fiber grating manufacturing method, optical fiber grating manufacturing apparatus, optical fiber grating, optical module, and optical communication system
US7298944B2 (en) 2000-11-28 2007-11-20 Fujikura Ltd. Method and device for manufacturing optical fiber grating, optical fiber grating, optical module, and optical communication system
GB2375830A (en) * 2001-05-22 2002-11-27 Marconi Caswell Ltd Creating Bragg gratings in optical waveguide devices
EP1717612A1 (en) * 2005-04-26 2006-11-02 Harris Corporation Apparatus and method for forming an optical microresonator

Also Published As

Publication number Publication date
GB2298287B (en) 1998-05-06
GB9503861D0 (en) 1995-04-19

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20070225