WO2000029884A1 - Imaged aperture mask grating writing - Google Patents

Imaged aperture mask grating writing Download PDF

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Publication number
WO2000029884A1
WO2000029884A1 PCT/AU1999/001002 AU9901002W WO0029884A1 WO 2000029884 A1 WO2000029884 A1 WO 2000029884A1 AU 9901002 W AU9901002 W AU 9901002W WO 0029884 A1 WO0029884 A1 WO 0029884A1
Authority
WO
WIPO (PCT)
Prior art keywords
mask
light
photosensitive
grating
waveguide
Prior art date
Application number
PCT/AU1999/001002
Other languages
French (fr)
Inventor
John Canning
Original Assignee
The University Of Sydney
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by The University Of Sydney filed Critical The University Of Sydney
Priority to AU15347/00A priority Critical patent/AU1534700A/en
Publication of WO2000029884A1 publication Critical patent/WO2000029884A1/en

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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
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
    • G02B6/02123—Refractive index modulation gratings, e.g. Bragg gratings characterised by the method of manufacture of the grating
    • G02B6/02142—Refractive index modulation gratings, e.g. Bragg gratings characterised by the method of manufacture of the grating based on illuminating or irradiating an amplitude mask, i.e. a mask having a repetitive intensity modulating pattern

Definitions

  • the present invention relates to the field of writing gratings in photosensitive optical wave guides and, in particular, discloses utilisation of an aperture mask in the construction of a written grating.
  • Gratings are often utilised for e.g. filtering signals and have become extremely important in optical fibre communications systems.
  • the present invention provides a method of writing a grating in a photosensitive waveguide comprising the steps of: (a) projecting light in a first direction through a mask having a series of spaced apart apertures;
  • the method can further comprise the step of translating the mask in a direction substantially transverse to the first direction.
  • the photosensitive waveguide can comprise an optical fiber.
  • the method can further comprise the step of moving said aperture mask in a direction substantially parallel to said first direction to vary a period of the grating .
  • the photosensitive waveguide can comprise a planar optical waveguide.
  • the invention may alternatively be defined as providing an apparatus for creating gratings in a photosensitive waveguide comprising: light projection means arranged to project light; a mask having a series of spaced apart apertures; and focusing means for focussing the light after it has passed through the mask to a focal point which, in use, is adjacent the photosensitive waveguide to image the mask in the photosensitive waveguide to thereby induce refractive index changes in regions of the photosensitive waveguide exposed to the light to write said grating.
  • Fig. 1 illustrates schematically the arrangement of a preferred embodiment.
  • an aperture mask and lensing system are utilised to write a grating in a photosensitive optical wave guide.
  • Fig. 1 there is illustrated 1 the basic arrangement of the preferred embodiment in which UV light 2 from a UV light source (not shown) impinges on an aperture mask 3 which is in the form of a series of spaced apart lines, the lines being opaque to UV light.
  • the UV light passes between the gaps in the aperture mask 3 and is imaged by a lens 4 having a focal length 5.
  • a photosensitive optical fiber is placed near the focal point 5 in the position 7 or 8.
  • the aperture mask is imaged on the photosensitive fiber 7, 8 so as to form a grating structure.
  • each photosensitive fiber 7, 8 can be moved forward and backwards so as to alter the periodicity of the grating (i.e. the image size).
  • the position of lensing element 4 can also be moved to again change the period of the grating.
  • the aperture mask 3 can be attached to a piezo-electric transducer 10 for programming complex movements of the aperture mask relative to the fiber for the creation of complex wave guide profiles.
  • the fibre only could be moved.
  • the aperture mask being far away from the wave guide, also allows full minimisation of vibrational coupling etc.
  • the light source 2, aperture mask 3 and imaging lens 4 can be translated along the fiber 7, 8 for creating long gratings or complex overlapping profiles .
  • the arrangement 1 of Fig. 1 has a number of advantages including that there is no zero order beams to be dealt with as is often the case in prior art interferometric techniques.
  • the period can be totally tunable by a number of independent means. Further, it is not necessary to utilise a coherent UV light source as is the case with interferometric techniques.
  • the arrangement also allows for top-hat intensity distribution gratings to be written. The arrangement is inexpensive. High intensities can be used at the wave guide without damaging the mask due to utilisation of the system which focuses the UV power on the grating and not at the mask.

Abstract

A method is disclosed of writing a grating in a photosensitive waveguide comprising the steps of: (a) projecting photosensitive light in a first direction through a mask (3) having a series of spaced apart opaque lines; (b) focusing the light after it has passed through the mask down to a focal point (5); and (c) placing the photosensitive waveguide (7, 8) in the region adjacent said focal point to image the mask in the photosensitive waveguide to thereby induce refractive index changes in regions of the photosensitive waveguide exposed to the light to write said grating.

Description

Imaged Aperture Mask Grating Writing
Field of the Invention
The present invention relates to the field of writing gratings in photosensitive optical wave guides and, in particular, discloses utilisation of an aperture mask in the construction of a written grating. Background of the Invention
The utilisation of periodic optical gratings is extremely important in optical wave guide applications utilising optical fibers and planar optical wave guides.
Gratings are often utilised for e.g. filtering signals and have become extremely important in optical fibre communications systems.
Various methods have been proposed for writing gratings in optical wave guide structures.
For example, the creation of a grating utilizing the interference pattern from two interfering coherent UV beams is well known. This technique for construction of Bragg gratings is fully described in US Patent No. 4,725,110 issued to H Glenn et. al. and US Patent No. 4,807,950 issued to W H Glenn et. al.
Bragg grating structures have become increasingly useful and in particular there is a demand for long grating structures having high quality properties. This lead to the general need to create improved grating structures using alternative grating writing techniques. Summary of the Invention
The present invention provides a method of writing a grating in a photosensitive waveguide comprising the steps of: (a) projecting light in a first direction through a mask having a series of spaced apart apertures;
(b) focusing the light after it has passed through the mask to a focal point; and (c) locating the photosensitive waveguide adjacent the focal point to image the mask in the photosensitive waveguide and to thereby induce refractive index changes in regions of the photosensitive waveguide exposed to the light to write said grating.
Preferably, the method can further comprise the step of translating the mask in a direction substantially transverse to the first direction. The photosensitive waveguide can comprise an optical fiber.
The method can further comprise the step of moving said aperture mask in a direction substantially parallel to said first direction to vary a period of the grating . The photosensitive waveguide can comprise a planar optical waveguide.
The invention may alternatively be defined as providing an apparatus for creating gratings in a photosensitive waveguide comprising: light projection means arranged to project light; a mask having a series of spaced apart apertures; and focusing means for focussing the light after it has passed through the mask to a focal point which, in use, is adjacent the photosensitive waveguide to image the mask in the photosensitive waveguide to thereby induce refractive index changes in regions of the photosensitive waveguide exposed to the light to write said grating. Brief Description of the Drawings
Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Fig. 1 illustrates schematically the arrangement of a preferred embodiment.
Description of the Preferred and Other Embodiments
In the preferred embodiment, an aperture mask and lensing system are utilised to write a grating in a photosensitive optical wave guide. Turning to Fig. 1, there is illustrated 1 the basic arrangement of the preferred embodiment in which UV light 2 from a UV light source (not shown) impinges on an aperture mask 3 which is in the form of a series of spaced apart lines, the lines being opaque to UV light. The UV light passes between the gaps in the aperture mask 3 and is imaged by a lens 4 having a focal length 5. A photosensitive optical fiber is placed near the focal point 5 in the position 7 or 8. The aperture mask is imaged on the photosensitive fiber 7, 8 so as to form a grating structure.
The position of each photosensitive fiber 7, 8 can be moved forward and backwards so as to alter the periodicity of the grating (i.e. the image size).
Alternatively, the position of lensing element 4 can also be moved to again change the period of the grating. Other modifications are possible. For example, the aperture mask 3 can be attached to a piezo-electric transducer 10 for programming complex movements of the aperture mask relative to the fiber for the creation of complex wave guide profiles. Alternatively, the fibre only could be moved. The aperture mask, being far away from the wave guide, also allows full minimisation of vibrational coupling etc. Further, the light source 2, aperture mask 3 and imaging lens 4 can be translated along the fiber 7, 8 for creating long gratings or complex overlapping profiles .
The arrangement 1 of Fig. 1 has a number of advantages including that there is no zero order beams to be dealt with as is often the case in prior art interferometric techniques. The period can be totally tunable by a number of independent means. Further, it is not necessary to utilise a coherent UV light source as is the case with interferometric techniques. The arrangement also allows for top-hat intensity distribution gratings to be written. The arrangement is inexpensive. High intensities can be used at the wave guide without damaging the mask due to utilisation of the system which focuses the UV power on the grating and not at the mask.
It would be appreciated by a person skilled in the art that numerous variations and/or modifications any be made to the present invention as shown in the specific O 00/29884 _ 4 --- PCT/AU99/01002
embodiment without departing from the spirit or scope of the invention as broadly described. The present embodiment is, therefore, to be considered in all respects to be illustrative and not restrictive.

Claims

We Cl aim :
1. A method of writing a grating in a photosensitive waveguide comprising the steps of:
(a) projecting photosensitive light in a first direction through a mask having a series of spaced apart apertures;
(b) focusing said light after it has passed through the mask to a focal point; and
(c) placing said photosensitive waveguide in the region adjacent said focal point to image the mask in the photosensitive waveguide to thereby induce refractive index changes in regions of the photosensitive waveguide exposed to the light to write said grating.
2. A method as claimed in claim 1 further comprising the step of translating said aperture mask in a direction substantially transverse to said first direction.
3. A method as claimed in claims 1 or 2 further comprising the step of moving the aperture mask in a direction substantially parallel to said first direction to vary the periodicity of said grating. . A method as claimed in any previous claim wherein said photosensitive waveguide comprises an optical fiber. 5. An apparatus for creating gratings in a waveguide comprising: light projection means adapted to project light; a mask having a series of spaced apart apertures; and focusing means for focussing light after it has passed through said mask to a focal point which, in use, is adjacent said photosensitive waveguide to image the mask in the photosensitive waveguide to thereby induce refractive index changes in regions of the photosensitive waveguide exposed to the light to write said grating.
PCT/AU1999/001002 1998-11-12 1999-11-12 Imaged aperture mask grating writing WO2000029884A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU15347/00A AU1534700A (en) 1998-11-12 1999-11-12 Imaged aperture mask grating writing

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPP7169A AUPP716998A0 (en) 1998-11-12 1998-11-12 Imaged aperture mask grating writing
AUPP7169 1998-11-12

Publications (1)

Publication Number Publication Date
WO2000029884A1 true WO2000029884A1 (en) 2000-05-25

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1999/001002 WO2000029884A1 (en) 1998-11-12 1999-11-12 Imaged aperture mask grating writing

Country Status (2)

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AU (1) AUPP716998A0 (en)
WO (1) WO2000029884A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1139123A1 (en) * 2000-03-30 2001-10-04 Optical Technologies Italia S.p.A. Method and apparatus for writing a Bragg grating in a waveguide
US6553163B2 (en) 2000-03-30 2003-04-22 Corning, Incorporated Method and apparatus for writing a Bragg grating in a waveguide
US6990272B2 (en) 2001-07-26 2006-01-24 Lxsix Photonics Inc. Apparatus for generating an optical interference pattern

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5104209A (en) * 1991-02-19 1992-04-14 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Communications Method of creating an index grating in an optical fiber and a mode converter using the index grating
WO1998007058A1 (en) * 1996-08-12 1998-02-19 Corning Incorporated Variable period amplitude grating mask and method for use
WO1998029767A1 (en) * 1997-01-04 1998-07-09 Munday Robert A Method and apparatus for creating holographic patterns

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5104209A (en) * 1991-02-19 1992-04-14 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Communications Method of creating an index grating in an optical fiber and a mode converter using the index grating
WO1998007058A1 (en) * 1996-08-12 1998-02-19 Corning Incorporated Variable period amplitude grating mask and method for use
WO1998029767A1 (en) * 1997-01-04 1998-07-09 Munday Robert A Method and apparatus for creating holographic patterns

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1139123A1 (en) * 2000-03-30 2001-10-04 Optical Technologies Italia S.p.A. Method and apparatus for writing a Bragg grating in a waveguide
WO2001073488A2 (en) * 2000-03-30 2001-10-04 Corning O.T.I. S.P.A. Method and apparatus for writing a bragg grating in a waveguide
WO2001073488A3 (en) * 2000-03-30 2002-01-03 Optical Technologies Italia Method and apparatus for writing a bragg grating in a waveguide
US6553163B2 (en) 2000-03-30 2003-04-22 Corning, Incorporated Method and apparatus for writing a Bragg grating in a waveguide
US6990272B2 (en) 2001-07-26 2006-01-24 Lxsix Photonics Inc. Apparatus for generating an optical interference pattern
US7079729B2 (en) 2001-07-26 2006-07-18 Lxsix Photonics Inc. Apparatus for generating an optical interference pattern

Also Published As

Publication number Publication date
AUPP716998A0 (en) 1998-12-10

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