GB2180667A - Manufacture of channel waveguides - Google Patents

Manufacture of channel waveguides Download PDF

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Publication number
GB2180667A
GB2180667A GB08622159A GB8622159A GB2180667A GB 2180667 A GB2180667 A GB 2180667A GB 08622159 A GB08622159 A GB 08622159A GB 8622159 A GB8622159 A GB 8622159A GB 2180667 A GB2180667 A GB 2180667A
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GB
United Kingdom
Prior art keywords
substrate
refractive index
channel
laser
waveguide
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
Application number
GB08622159A
Other versions
GB2180667B (en
GB8622159D0 (en
Inventor
John Stephen Mccormack
Noorallah Nourshargh
Elizabeth Mary Starr
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.)
General Electric Co PLC
Original Assignee
General Electric Co PLC
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 General Electric Co PLC filed Critical General Electric Co PLC
Publication of GB8622159D0 publication Critical patent/GB8622159D0/en
Publication of GB2180667A publication Critical patent/GB2180667A/en
Application granted granted Critical
Publication of GB2180667B publication Critical patent/GB2180667B/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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/13—Integrated optical circuits characterised by the manufacturing method
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C23/00—Other surface treatment of glass not in the form of fibres or filaments
    • C03C23/0005—Other surface treatment of glass not in the form of fibres or filaments by irradiation
    • C03C23/0025—Other surface treatment of glass not in the form of fibres or filaments by irradiation by a laser beam

Abstract

The refractive index of a material is changed by heating a localised area 4. The area 4 retains an increased refractive index, relative to the rest of the substrate 2, on cooling, and may then be used as a waveguide channel. The heating means is preferably a focussed 3 laser beam generated from a CO2 or NdYAG laser L. The substrate material maybe germania-doped silica 2 on a base of silica or quartz 1. The scan speed, position and beam temperature of the laser are controlled by system 8,6, 7. <IMAGE>

Description

SPECIFICATION The manufacture of channel waveguides This invention relates to the ma nufactu re of cha nnel waveguides in integrated optical components, such waveguides consisting of a path of relatively high refractive index material within a base material having a lower refractive index.
Several techniques have already been disclosed for producing such channel waveguides. One method involves cutting a groove in a substrate of said base material and then filling it with a higher refractive index medium. Another method involves etching away part ofthe surface of a substrate of a suitably high refractive index material to leave a raised region of said material extending along the required waveguide path, and then covering this raised region with a lower refractive index medium. Anothertechnique comprises depositing a thin metallic layer on to a substrate of said base material and then diffusing it into the substrate by heat to form a high refractive index waveguide region.
Afurthertechnique which has recently been disclosed comprises forming two parallel grooves in a substrate of porous titanium dioxide, and following consolidation in a furnace the raised area between the grooves becomes the waveguide channel.
However all of these known processes require a plurality of different steps, often in different equipment, in orderto form the completed channel waveguides.
An object of the present invention isto provide an alternative, simpler, method of forming a channel waveguide, and is based on the discovery that certain materials have a refractive index which can be increased on heating, and possess the property of retaining the higher refractive index condition when the temperature is subsequently reduced.
Accordingly, in the manufacture of a channel waveguide, a substrate formed of such a material is heated along a path required to form the desired waveguide channel to a temperature such that on subsequent cooling there is formed along said path a region of material having a refractive index which is higher, by a predetermined amount, than the adjacent substrate material.
The width of the region forming thewaveguide channel will usually be ofthe order of a few microns, and the heating of the substrate is conveniently achieved by focussing a laser beam on to the sub- strate, and producing a relative movement between the beam and the substrate, in order to effectthe heating along the desired waveguide path.
The waveguide channels produced will normally have a refractive index profile of Gaussian shape in the plane of the substrate, and may be formed as straight lines, circles orany required geometry. It is believed that the heating of the substrate material causes the atoms in the material to re-arrangethemselves, so as to produce the increased refractive index, the re-arranged condition being maintained on subsequent cooling.
A CO2 laser may be utilised to delineate thewaveguide channels, but if smaller dimensions are required ashorterwavelength laser, such as a NdYAG laser, could be employed.
Germania doped silica is one material which pos sepses the required properties of retaining an increased refractive index on being heated, and a substrate ofthis material is conveniently deposited as a layer on a base material for example of quartz or silica. The layer can, for example, be deposited by a low pressure gas phase reaction. Typically a plasma may be used asthe activating mediumforthechemi- cal reaction between suitable precursors, such as SiCI4, GeCI4, and 02, the background temperature conveniently being maintained at approximately 1100"C during the deposition process. Uniform layers of variable refractive index and thickness can be produced in this manner.These layers are subsequently heated by a laser beam in the desired pattern ofthe channel waveguide.
The method ofthe invention has the advantage that it is a direct write system with no need forfurther deposition or etching, and as it is a single laser-beam interaction effect, the possibility of misalignment of two separately formed grooves, as in a previous method offorming channel waveguides as described above, is completely avoided.
The manufacture of one channel waveguide in ac cordance with the invention will now be described by way of example with reference to the accompanying drawing.
This illustrates diagrammatically a perspective view of a generally planar plate 1 of silica having on its uppermost surface a layer 2 of german ia-doped silica approximately 5 pssm thick, the layer having been formed by a plasma-assisted low pressure gas phase reaction.
The output of a CO2 laser L is focussed by means of a lens3 on to the surface ofthe layer2 so asto heat the layer locally to an extent which produces an increase in the refractive index from about 1.477 to 1.479. The plate 1 is simultaneously moved relative to the output of the laser to produce a path 4 of material within the layer 2 having an increased refractive index, and it has been found that the heated material along this path retains the increased refractive index on subsequent cooling.
In the drawing the plate 1 is shown mounted on a support5which is movable parallel to the plane of the plate intwo directions at rightanglesto each other by means of a computerh controlled XYtranslator shown diagrammatically at 6. A laser control circuit 7 is also conveniently controlled by the computer 8. The amount of heating of the layer 2 which is produced is determined by the laser power, the scanning speed and the degree offocussing, and by an appropriate variation of one or more of these parameters waveguide channels having different refractive indices and/or shapes of cross-section can be obtained.
Moreover by controlling the movement of the support 5 it is possible to form complex shapes of have guide channels, with any desired geometry.
1. The manufacture of a channel waveguide com
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION The manufacture of channel waveguides This invention relates to the ma nufactu re of cha nnel waveguides in integrated optical components, such waveguides consisting of a path of relatively high refractive index material within a base material having a lower refractive index. Several techniques have already been disclosed for producing such channel waveguides. One method involves cutting a groove in a substrate of said base material and then filling it with a higher refractive index medium. Another method involves etching away part ofthe surface of a substrate of a suitably high refractive index material to leave a raised region of said material extending along the required waveguide path, and then covering this raised region with a lower refractive index medium. Anothertechnique comprises depositing a thin metallic layer on to a substrate of said base material and then diffusing it into the substrate by heat to form a high refractive index waveguide region. Afurthertechnique which has recently been disclosed comprises forming two parallel grooves in a substrate of porous titanium dioxide, and following consolidation in a furnace the raised area between the grooves becomes the waveguide channel. However all of these known processes require a plurality of different steps, often in different equipment, in orderto form the completed channel waveguides. An object of the present invention isto provide an alternative, simpler, method of forming a channel waveguide, and is based on the discovery that certain materials have a refractive index which can be increased on heating, and possess the property of retaining the higher refractive index condition when the temperature is subsequently reduced. Accordingly, in the manufacture of a channel waveguide, a substrate formed of such a material is heated along a path required to form the desired waveguide channel to a temperature such that on subsequent cooling there is formed along said path a region of material having a refractive index which is higher, by a predetermined amount, than the adjacent substrate material. The width of the region forming thewaveguide channel will usually be ofthe order of a few microns, and the heating of the substrate is conveniently achieved by focussing a laser beam on to the sub- strate, and producing a relative movement between the beam and the substrate, in order to effectthe heating along the desired waveguide path. The waveguide channels produced will normally have a refractive index profile of Gaussian shape in the plane of the substrate, and may be formed as straight lines, circles orany required geometry. It is believed that the heating of the substrate material causes the atoms in the material to re-arrangethemselves, so as to produce the increased refractive index, the re-arranged condition being maintained on subsequent cooling. A CO2 laser may be utilised to delineate thewaveguide channels, but if smaller dimensions are required ashorterwavelength laser, such as a NdYAG laser, could be employed. Germania doped silica is one material which pos sepses the required properties of retaining an increased refractive index on being heated, and a substrate ofthis material is conveniently deposited as a layer on a base material for example of quartz or silica. The layer can, for example, be deposited by a low pressure gas phase reaction. Typically a plasma may be used asthe activating mediumforthechemi- cal reaction between suitable precursors, such as SiCI4, GeCI4, and 02, the background temperature conveniently being maintained at approximately 1100"C during the deposition process. Uniform layers of variable refractive index and thickness can be produced in this manner.These layers are subsequently heated by a laser beam in the desired pattern ofthe channel waveguide. The method ofthe invention has the advantage that it is a direct write system with no need forfurther deposition or etching, and as it is a single laser-beam interaction effect, the possibility of misalignment of two separately formed grooves, as in a previous method offorming channel waveguides as described above, is completely avoided. The manufacture of one channel waveguide in ac cordance with the invention will now be described by way of example with reference to the accompanying drawing. This illustrates diagrammatically a perspective view of a generally planar plate 1 of silica having on its uppermost surface a layer 2 of german ia-doped silica approximately 5 pssm thick, the layer having been formed by a plasma-assisted low pressure gas phase reaction. The output of a CO2 laser L is focussed by means of a lens3 on to the surface ofthe layer2 so asto heat the layer locally to an extent which produces an increase in the refractive index from about 1.477 to 1.479. The plate 1 is simultaneously moved relative to the output of the laser to produce a path 4 of material within the layer 2 having an increased refractive index, and it has been found that the heated material along this path retains the increased refractive index on subsequent cooling. In the drawing the plate 1 is shown mounted on a support5which is movable parallel to the plane of the plate intwo directions at rightanglesto each other by means of a computerh controlled XYtranslator shown diagrammatically at 6. A laser control circuit 7 is also conveniently controlled by the computer 8. The amount of heating of the layer 2 which is produced is determined by the laser power, the scanning speed and the degree offocussing, and by an appropriate variation of one or more of these parameters waveguide channels having different refractive indices and/or shapes of cross-section can be obtained. Moreover by controlling the movement of the support 5 it is possible to form complex shapes of have guide channels, with any desired geometry. CLAIMS
1. The manufacture of a channel waveguide com prises heating a substrate, formed of a material whose refractive index can be increased on heating and which retainsthe higher refractive index condi- tion on subsequent cooling, along a path required to form the waveguide channel, to a temperature such thatonsubsequentcoolingthereisformedalong said path a region of material having a refractive index which is higher, buy a predetermined amount, than the adjacent substrate material.
2. The manufacture of a channel waveguide according to Claim 1 wherein the heating ofthe substrate is achieved by focussing a laser beam on to the substrate, and producing a relative movement between the beam and the substrate, in order to effect the heating along the desired waveguide path.
3. The manufacture of a channel waveguide according to Claim 2 wherein heating of the substrate is effected so as to produce a waveguide channel having a Gaussian shaped refractive index profile in the plane ofthe substrate.
4. The manufacture of a channel waveguide according to Claim 2 or3wherein the laser is a CO2 laser.
5. The manufacture of a channel waveguide according to Claim 2 or3 wherein the laser is a NdYAG laser.
6. The manufacture of a channel waveguide according to any preceding Claim wherein the substrate material is germaniah doped silica.
7. The manufacture of a channel waveguide according to Claim 6wherein the substrate comprises a layer of said germania-doped silica on a base material.
8. The manufacture of a channel waveguide according to Claim 7 wherein the base material is quartz or silica and the substrate layer is initially deposited on the base material by a low pressure gas phase reaction.
9. The manufacture of a channel waveguide car- ried outsubstantially as shown in and as here inbefore described with reference to the accompany ing drawing.
GB8622159A 1985-09-23 1986-09-15 The manufacture of channel waveguides Expired GB2180667B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB858523433A GB8523433D0 (en) 1985-09-23 1985-09-23 Channel waveguides

Publications (3)

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GB8622159D0 GB8622159D0 (en) 1986-10-22
GB2180667A true GB2180667A (en) 1987-04-01
GB2180667B GB2180667B (en) 1989-09-13

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GB8622159A Expired GB2180667B (en) 1985-09-23 1986-09-15 The manufacture of channel waveguides

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0281800A2 (en) * 1987-03-13 1988-09-14 Hitachi, Ltd. Optical waveguide and method for fabricating the same
GB2245984A (en) * 1990-06-29 1992-01-15 Hitachi Cable Rare earth element-doped optical waveguide
US5117470A (en) * 1990-02-26 1992-05-26 Nippon Telegraph And Telephone Corporation Guided-wave optical circuit and method for adjusting a characteristic thereof
EP0665451A1 (en) * 1993-12-30 1995-08-02 AT&T Corp. Mode-field transforming optical waveguide
EP1183214A1 (en) * 1999-04-09 2002-03-06 The University of New Mexico Large photosensitivity in lead silicate glasses

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108031969A (en) * 2017-12-29 2018-05-15 广东工业大学 A kind of micro-nano channel production method and device

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3809686A (en) * 1970-03-19 1974-05-07 Bell Telephone Labor Inc Transparent media capable of photoinduced refractive index changes and their application to light guides and the like
GB1421401A (en) * 1972-03-30 1976-01-21 Corning Glass Works Planar optical waveguides
US4022602A (en) * 1975-10-30 1977-05-10 The United States Of America As Represented By The Secretary Of The Navy Method of fabricating low-loss channel optical waveguides
US4090776A (en) * 1976-10-13 1978-05-23 Honeywell Inc. Fabrication of optical waveguides
US4111520A (en) * 1975-01-13 1978-09-05 Honeywell Inc. Fabrication of optical waveguides
GB2131417A (en) * 1982-12-02 1984-06-20 Western Electric Co Ltd Optical device and reform fabrication

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2191603A (en) * 1986-06-13 1987-12-16 Northern Telecom Ltd Optical conductor having at least three layers

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3809686A (en) * 1970-03-19 1974-05-07 Bell Telephone Labor Inc Transparent media capable of photoinduced refractive index changes and their application to light guides and the like
GB1421401A (en) * 1972-03-30 1976-01-21 Corning Glass Works Planar optical waveguides
US4111520A (en) * 1975-01-13 1978-09-05 Honeywell Inc. Fabrication of optical waveguides
US4022602A (en) * 1975-10-30 1977-05-10 The United States Of America As Represented By The Secretary Of The Navy Method of fabricating low-loss channel optical waveguides
US4090776A (en) * 1976-10-13 1978-05-23 Honeywell Inc. Fabrication of optical waveguides
GB2131417A (en) * 1982-12-02 1984-06-20 Western Electric Co Ltd Optical device and reform fabrication

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
APPLIED PHYSICS LETTERS, CHANDROSS ET AL 24, P72. *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0281800A2 (en) * 1987-03-13 1988-09-14 Hitachi, Ltd. Optical waveguide and method for fabricating the same
US4856859A (en) * 1987-03-13 1989-08-15 Hitachi, Ltd. Optical waveguide and method for fabricating the same
EP0281800B1 (en) * 1987-03-13 1994-05-04 Hitachi, Ltd. Optical waveguide and method for fabricating the same
US5117470A (en) * 1990-02-26 1992-05-26 Nippon Telegraph And Telephone Corporation Guided-wave optical circuit and method for adjusting a characteristic thereof
GB2245984A (en) * 1990-06-29 1992-01-15 Hitachi Cable Rare earth element-doped optical waveguide
US5206925A (en) * 1990-06-29 1993-04-27 Hitachi Cable Limited Rare earth element-doped optical waveguide and process for producing the same
GB2245984B (en) * 1990-06-29 1994-06-15 Hitachi Cable Rare earth element-doped optical waveguide and process for producing the same
EP0665451A1 (en) * 1993-12-30 1995-08-02 AT&T Corp. Mode-field transforming optical waveguide
EP1183214A1 (en) * 1999-04-09 2002-03-06 The University of New Mexico Large photosensitivity in lead silicate glasses
EP1183214A4 (en) * 1999-04-09 2008-12-17 Univ New Mexico Large photosensitivity in lead silicate glasses

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Publication number Publication date
GB2180667B (en) 1989-09-13
GB8622159D0 (en) 1986-10-22
GB8523433D0 (en) 1985-10-30

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