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WO1993002018A1 - Dispositif de transmission de la lumiere presentant des zones d'indices de refraction differents - Google Patents

Dispositif de transmission de la lumiere presentant des zones d'indices de refraction differents Download PDF

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Publication number
WO1993002018A1
WO1993002018A1 PCT/AU1992/000354 AU9200354W WO9302018A1 WO 1993002018 A1 WO1993002018 A1 WO 1993002018A1 AU 9200354 W AU9200354 W AU 9200354W WO 9302018 A1 WO9302018 A1 WO 9302018A1
Authority
WO
WIPO (PCT)
Prior art keywords
fibre
core
bonds
weak
regions
Prior art date
Application number
PCT/AU1992/000354
Other languages
English (en)
Inventor
Simon Poole
Mark Sceats
Original Assignee
The University Of Sydney
Telstra Corporation Limited
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, Telstra Corporation Limited filed Critical The University Of Sydney
Publication of WO1993002018A1 publication Critical patent/WO1993002018A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
    • C03B37/01807—Reactant delivery systems, e.g. reactant deposition burners
    • 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
    • C03C13/00—Fibre or filament compositions
    • C03C13/04—Fibre optics, e.g. core and clad fibre compositions
    • C03C13/045—Silica-containing oxide glass compositions
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00—Fibre product details, e.g. structure, shape
    • C03B2203/10—Internal structure or shape details
    • C03B2203/18—Axial perturbations, e.g. in refractive index or composition

Definitions

  • This invention relates to light transmitting devices which incorporate periodic regions of differing refractive index and to a method of producing such devices.
  • the invention has particular application to optical fibres, including multi-core fibres, and is hereinafter described in the context of such fibres. However, it will be understood that the invention may have broader application, for example to planar waveguides and other light transmitting devices.
  • Optical fibres having localised regions of differing refractive index are known in the art and have various applications. For example, they may be employed for effecting relative dispersion of light of different wavelengths and for enhancing or creating non-linear optical properties that may be used in the control of optical information. Additionally, they may be employed as filters, by reflecting and transmitting light of specific wavelengths, and they may be used to provide coupling between modes of a fibre or between the cores of a multi-core fibre. Furthermore, they may be employed as sensors or modulators in devices which are employed for measuring changes in such physical characteristics as strain and temperature.
  • Localised regions of differing refractive index have been produced in planar waveguides and optical fibres, using prior art techniques, by shaping (e.g. corrugating) a surface which is located at or near the light propagating region of the waveguides and fibres.
  • Various techniques have been employed for this purpose, including photo or electron beam lithography and, in the case of fibres, the required surface has been produced after removing the relatively thick cladding at the required locations and/or by using a D-shaped fibre.
  • regions having different refractive indices have been produced in planar waveguides and fibres, again using prior art procedures, by * doping the waveguides and fibres using such techniques as ion implantation, electron beam irradiation and in-diffusion processes.
  • the present invention is directed to a development of the latter approach and it flows from a discovery made by the inventors that, by creating weak chemical bonds
  • the present invention provides a method of forming regions of differing refractive index within a glass light transmitting device and which comprises the steps of:
  • Oxide glasses are amorphous materials which consist of a network of one or more types of glass-forming atoms such as Si, Ge, B, P and As bonded to a number of oxygen atoms. Additional, conditional, glass-forming atoms such as Te, Se, Mo, W, Bi, Al, Ga and V may also be incorporated. Generally, these various glass-forming atoms are characterised by being linked to one another through an intermediate oxygen atom and the linking bonds are referred to herein as "oxygen-linking bonds". However, it is possible that the atoms may be directly bonded without an intermediate oxygen atom and such bonds are referred to herein as "weak chemical bonds", “weak bonds” or “wrong bonds”.
  • the invention also provides a glass light transmitting device per se. having regions of differing refractive index, when formed by the above defined method.
  • the device may comprise a length of optical fibre of any desired configuration, a planar waveguide or other light transmitting device.
  • the weak bonds may be created during formation of the preform by depositing the core and/or cladding under oxygen deficient conditions and/or by doping the portion of the fibre which is to contain the weak bonds with at least one dopant material that is selected to contribute to the weak chemical binding.
  • the dopant material(s) also has/have the property of enhancing differential contraction of the core and/or cladding during drawing of the fibre. That is, the dopant is 01
  • - 4 - preferably selected to aid in the creation of tensile stress in the core and/or the cladding at a level which is as high as possible (typically in the order of 5MPa to 600MPa) but which is not so high as to cause breakage of a significant number of the weak bonds during the fibre drawing process.
  • the regions of differing refractive index may be located in the core or the cladding or both the core and the cladding of an optical fibre, in most applications of the invention such regions will be located in the core.
  • the cladding of the fibre may be formed in the usual way from Si ⁇ 2, optionally with 2O5 and F dopants, and the core may be formed as a Ge ⁇ 2 doped Si ⁇ 2 structure.
  • Such cladding and core structures have Si-0 and Ge-0 bonds and, as above mentioned, the weak bonds (or "wrong" bonds) , for example Ge-Ge, Si-Si or Ge-Si bonds, may be created by reducing the pressure of O2 carrier gas during vapour deposition of the core and/or the cladding in the fibre preform.
  • the weak bonds might alternatively or additionally be created by substituting O2 with an oxygen deficient carrier gas and/or by depositing the Ge doped regions at a higher-than-optimum temperature which encourages the formation of a Ge sub-oxide.
  • the weak bonds may be created by doping or co-doping the core and/or the cladding with aluminium, boron, titanium, lead, bismuth, arsenic, selenium, phosphorous or such other dopant as will contribute to the creation of weak bonds.
  • Materials that have been found to be particularly suitable for doping the stress-producing regions include B 2°3' ⁇ 5 2°5' A - ⁇ 2°3 anc - Ge ⁇ 2' either individually or in various combinations.
  • External photo-irradia ion of the device may be effected by direct single-beam irradiation from a laser source and by either masking the fibre or by periodically advancing the fibre relative to the source.
  • This approach is suitable for the production of a grating - 5 - having millimetric periodicity.
  • Gratings having micrometric or sub-micrometrie periodicity may be produced by interferometric processes.
  • Internal photo-irradiation may be effected by propagating light through the fibre in a manner so as to create standing waves with nodes positioned to cause irradiation at the required spacings.
  • the irradiation will typically be effected at an energy level in the range 2eV to 7eV.
  • the effect of the photo-irradiation may be increased by optimising the initial stress levels of the regions containing the weak bonds. This may be achieved either by optimising the stresses generated when doping the regions containing the weak bonds or, alternatively, by introducing other regions within the fibre which act on the regions containing the weak bonds so as to optimise the induced stresses within those regions.
  • Such stresses may be introduced in a circularly symmetric form or in an asymmetric manner, the latter being known from prior art literature to form highly birefringent fibres based on the stress-optic effect.
  • Figure 1 shows a schematic representation of a modified chemical vapour deposition process for forming a fibre preform
  • Figure 2 shows a schematic representation of a method of drawing a fibre from a preform
  • Figure 3 shows a schematic representation of an arrangement for side writing or photo-irradiating a length of fibre
  • Figure 4 shows a schematic representation of an alternative arrangement for side writing or photo-irradiating a length of fibre. 018
  • the fibre itself is produced by joining two 100cm lengths of OPTIQ-100 (trade mark) fused quartz tubing having outside and inside diameters of 20mm and 16mm respectively and by soaking the tubing for 12 hours in a PYRONEG (trade mark) solution.
  • the tube is thoroughly rinsed with demineralised water and acetone and is then dried with a flow of nitrogen.
  • the cleaned and dried tube is placed in a glass working lathe, as indicated schematically in Figure 1, and the exterior of the tube is wiped with acetone.
  • the tube is rotated in the lathe and warmed with a natural gas torch which is passed along the exterior of the tube.
  • the interior of the .tube is etched with a flow of 0 2 saturated with SFg and the 0 2 flow is maintained throughout ensuing depositions.
  • the temperature of the torch is adjusted to approximately 1700°C and a Si ⁇ 2/ 2-*5/F cladding region is deposited using the conventional modified chemical vapour deposition (MCVD) process with the sources of Si0 2 , P2O5 and F being SiCl 4 , POCI3 and SFg respectively.
  • MCVD modified chemical vapour deposition
  • SiCl 4 , POCI3 and SFg is terminated and the torch temperature is reduced to approximately 1200-C. Then, SiCl 4 and (2-6 wt.%) GeCl 4 are introduced to deposit a Si ⁇ 2/Ge ⁇ 2 frit.
  • One end of the tube is then sealed by melting and the tube is removed from the lathe.
  • a pre-prepared solution of aluminium chloride (AICI3) (approximately 1.0 wt.%) is poured into the tube and the tube is stored for approximately 12 hours to allow the frit to be wet by the solution.
  • the solution is prepared by dissolving the AICI3 in water. Excess solution is drained from the tube, the sealed end is cut from the tube and the exterior of the tube is cleaned with acetone prior to re-mounting the tube in the lathe. - 7 -
  • the tube in the lathe is heated at a temperature below 1000-C with a flow of 0 2 being introduced to convey free water from within the tube. Thereafter, the torch temperature is increased to approximately 2000°C to sinter the frit and collapse the preform. Optionally, a slight negative pressure may be maintained during the collapsing process to ensure that the core of the final fibre will be elliptical in shape if a birefringent fibre is required.
  • the preform is removed from the lathe and its refractive index is measured for classification purposes.
  • Optical fibre is drawn from the preform in the conventional manner, using a fibre drawing/coating system as shown schematically in Figure 2.
  • the level of stress within the fibre may be altered as required by changing the fibre drawing conditions.
  • Photo-irradiation of the core may be effected in the manner illustrated in Figure 3, using an Excimer laser which provides a 248nm output.
  • the fibre is caused to traverse through the laser beam in incremental steps and irradiation is effected by way of the illustrated mask.
  • photo-irradiation of the core may be effected holographically in the manner illustrated schematically in Figure 4, using an Excimer pumped dye laser which provides a frequency doubled 488nm output to an interferometer.
  • the interferometer comprises a cylindrical lens, beam splitter and mirror surfaces arranged to provide for beam interference and, thus, the - 8 - required interference pattern at the side of the optical fibre that is to be irradiated.
  • the fibre be subjected to single pulse exposures, to obviate problems associated with lack of stability in the irradiating system, but in any case an energy level in the order of 2 to 7 eV will typically be required to effect breaking of a significant number of the weak bonds for the purpose of achieving significant increases in the refractive index at the irradiated sites.
  • Optical fibres produced in accordance with the prescribed method have exhibited localised refractive index increases in the order of 10 .
  • fibre polarisation rocking filters which show a strong dependence of transmission within wavelengths for a given input polarisation state, can be fabricated by perturbing a birefringent fibre in such a manner that the perturbation beat length matches the birefringent beat length between the two polarisation modes.
  • the perturbations act to couple light launched on one polarisation state of the fibre into the other polarisation state, with the coupling being highly wavelength dependent because it only occurs where the birefringent beat length is equal to the perturbation beat length and the birefringent beat length is highly dispersive (wavelength-dependent) .
  • perturbations can be induced by suitably irradiating the fibre using an Excimer laser operating at 248nm to produce a modulation of the fibre birefringence as a consequence of the stress relief which is derived from the above described procedure.
  • an Excimer laser operating at 248nm to produce a modulation of the fibre birefringence as a consequence of the stress relief which is derived from the above described procedure.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Optics & Photonics (AREA)
  • Physics & Mathematics (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

Abstract

Procédé d'élaboration de zones périodiques d'indices de réfraction différents dans un dispositif de transmission de lumière en verre, notamment dans une fibre optique. Le dispositif est réalisé de manière à obtenir des liaisons chimiques lâches, exerçant une énergie de liaison limitée par rapport à celle des liaisons oxygènes. La contrainte de traction s'exerce dans une partie du dispositif en verre renfermant les liaisons lâches, à un niveau permettant la préservation d'une majorité de ces liaisons lâches. Le système, une fois réalisé, est soumis à un rayonnement optique en ses zones périodiques espacées, ce rayonnement ayant un niveau d'énergie suffisant pour rompre les liaisons chimiques lâches et provoquer ainsi un abaissement du niveau de contrainte et, en corollaire, une augmentation de l'indice de réfraction dans les zones périodiques exposées du dispositif.
PCT/AU1992/000354 1991-07-15 1992-07-15 Dispositif de transmission de la lumiere presentant des zones d'indices de refraction differents WO1993002018A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPK7215 1991-07-15
AUPK721591 1991-07-15

Publications (1)

Publication Number Publication Date
WO1993002018A1 true WO1993002018A1 (fr) 1993-02-04

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6422042B1 (en) 1994-12-20 2002-07-23 Corning Incorporated Rit method of making optical fiber having depressed index core region

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3542536A (en) * 1967-09-01 1970-11-24 Hazeltine Research Inc Method of forming optical waveguide by irradiation of dielectric material
US4229070A (en) * 1978-07-31 1980-10-21 Corning Glass Works High bandwidth optical waveguide having B2 O3 free core and method of fabrication
JPS61191543A (ja) * 1985-02-15 1986-08-26 Furukawa Electric Co Ltd:The 石英系光フアイバ
JPS61262708A (ja) * 1985-05-17 1986-11-20 Sumitomo Electric Ind Ltd １．５ミクロン帯用シングルモ−ド光フアイバ
JPS6462603A (en) * 1987-09-02 1989-03-09 Furukawa Electric Co Ltd Optical transmission fiber
JPH01298037A (ja) * 1988-05-26 1989-12-01 Fujikura Ltd Ｎａ変換光ファイバの製造方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3542536A (en) * 1967-09-01 1970-11-24 Hazeltine Research Inc Method of forming optical waveguide by irradiation of dielectric material
US4229070A (en) * 1978-07-31 1980-10-21 Corning Glass Works High bandwidth optical waveguide having B2 O3 free core and method of fabrication
JPS61191543A (ja) * 1985-02-15 1986-08-26 Furukawa Electric Co Ltd:The 石英系光フアイバ
JPS61262708A (ja) * 1985-05-17 1986-11-20 Sumitomo Electric Ind Ltd １．５ミクロン帯用シングルモ−ド光フアイバ
JPS6462603A (en) * 1987-09-02 1989-03-09 Furukawa Electric Co Ltd Optical transmission fiber
JPH01298037A (ja) * 1988-05-26 1989-12-01 Fujikura Ltd Ｎａ変換光ファイバの製造方法

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, C-397, page 149; & JP,A,61 191 543, (THE FURUKAWA ELECTRIC CO LTD), 26 August 1986. *
PATENT ABSTRACTS OF JAPAN, C-689, page 99; & JP,A,1 298 037, (FUJIKURA LTD), 1 December 1989. *
PATENT ABSTRACTS OF JAPAN, P-566, page 70; & JP,A,61 262 708, (SUMITOMO ELECTRIC IND LTD), 20 November 1986. *
PATENT ABSTRACTS OF JAPAN, P-888, page 136; & JP,A,1 062 603, (THE FURUKAWA ELECTRIC CO LTD), 9 March 1989. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6422042B1 (en) 1994-12-20 2002-07-23 Corning Incorporated Rit method of making optical fiber having depressed index core region

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