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WO2003010577A1 - Boitier a compensation de temperature pour reseaux de fibres optiques - Google Patents

Boitier a compensation de temperature pour reseaux de fibres optiques Download PDF

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Publication number
WO2003010577A1
WO2003010577A1 PCT/SG2002/000164 SG0200164W WO03010577A1 WO 2003010577 A1 WO2003010577 A1 WO 2003010577A1 SG 0200164 W SG0200164 W SG 0200164W WO 03010577 A1 WO03010577 A1 WO 03010577A1
Authority
WO
WIPO (PCT)
Prior art keywords
temperature compensation
package according
compensation package
grating element
fibre
Prior art date
Application number
PCT/SG2002/000164
Other languages
English (en)
Inventor
Chao Lu
Tee Hiang Cheng
Zhi Hao Chen
Original Assignee
Nanyang Technological University
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 Nanyang Technological University filed Critical Nanyang Technological University
Publication of WO2003010577A1 publication Critical patent/WO2003010577A1/fr

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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
    • G02B6/02171—Refractive index modulation gratings, e.g. Bragg gratings characterised by means for compensating environmentally induced changes
    • G02B6/02176—Refractive index modulation gratings, e.g. Bragg gratings characterised by means for compensating environmentally induced changes due to temperature fluctuations
    • G02B6/0218—Refractive index modulation gratings, e.g. Bragg gratings characterised by means for compensating environmentally induced changes due to temperature fluctuations using mounting means, e.g. by using a combination of materials having different thermal expansion coefficients

Definitions

  • the present invention relates to a temperature compensation package for optic fibre grating elements.
  • the invention relates to a temperature compensation package for a fibre Bragg grating.
  • the fibre Bragg gratings can be uniform gratings, chirped gratings and blazed gratings.
  • Fibre Bragg gratings are promising components for applications in wavelength division multiplexing fibre communication systems, dispersion compensation, laser stabilization and gain flattening in erbium doped fibre amplifiers, etc.
  • the stabilized wavelength reference is highly desirable.
  • the central wavelength of the grating is sensitive to a number of physical parameters (e.g., temperature, strain, etc). Performance of the grating may therefore vary due to changes in these parameters. Thus, it is of practical importance to develop means to maintain grating performance under varying operating conditions.
  • the central wavelength of the grating is shifted when the temperature T or the strain ⁇ that applied to the grating is changed.
  • the change in the wavelength — ⁇ can be expressed as:
  • ⁇ r J S the change in the grating temperature; is the central wavelength of the grating; ex , is the coefficients of thermal expansion of the fibre containing the optical grating; ⁇ , is the thermo-optic coefficient of the fibre containing the optical grating, and p e is the effective photo-elastic constant of the fibre.
  • the first term in equation (1) is the inherent temperature dependence of the grating.
  • the second term measures the effect due to the strain on the optical fibre containing the grating. As can be seen from equation (1), one can choose suitable strain to compensate for the change in the wavelength of the grating with the temperature.
  • US Pat. No. 6044189 describes an apparatus that can provide temperature compensation for the grating.
  • the apparatus comprises a stack of two members with each member having an interface surface bonded to an interface surface of each adjacent member. Both members have two different temperature coefficients of expansion.
  • the grating is attached to a mounting surface on the first member in the stack. The mounting surface is located on the opposite side of the first member from the interface surface.
  • the device forces an elongation of the grating with decreasing temperature, or a shortening of the grating with increasing temperature, which compensates for the change in the wavelength of the grating with a change in temperature.
  • US Patent No. 5694503 describes a device that comprises a support member and the fibre grating that is attached to the support member.
  • the support member is selected to have a negative coefficient of thermal expansion, which compresses the fibre grating as the temperature increases.
  • US Patent 5991483 also describes a package which comprises two threaded members with different thread counts to control axial strain on the grating for temperature compensation.
  • the present invention provides a temperature compensation package for a fibre grating element, comprising a member connected to said fibre grating element for transmitting a force to said fibre grating element, said member adapted to be flexed to adjust the force transmitted to said fibre grating element, and means to control said flexing of said member.
  • the invention provides a structure for producing tension or compression strain in the fibre grating element to compensate for a change in the centre wavelength of the fibre grating element caused by a variation of temperature.
  • control means flexes said member to form an arcuate shape.
  • the member is initially arcuate in shape.
  • the control means is preferably a temperature compensating element which responds to a variation in temperature to control the force applied to the fibre grating element.
  • the control means can be an actuator to actively control the force applied to the fibre grating element.
  • the member is a flexible surface on a first beam.
  • the flexible surface preferably has a groove for receiving the fibre grating element. This inhibits damage to the fibre grating element.
  • the groove is V-shaped in cross-section.
  • control means has a positive or negative coefficient of thermal expansion.
  • control means and the flexible surface connecting the fibre grating element are located on the same face of the first beam.
  • control means and the flexible surface connecting the fibre grating element are located on opposing faces of the first beam.
  • the first beam is connected to a second beam.
  • the control means is preferably located between the first beam and the second beam. In one preferred embodiment, the control means is centrally located between the first beam and the second beam.
  • the first beam and the second beam can be connected at their respective ends.
  • the width of the first beam is preferably more than or equal to the width of the second beam. This reduces the risk of damage to the fibre grating element from contact with the second beam.
  • the length of the first beam and the length of the second beam each can be more than the length of the fibre grating element.
  • the fibre grating element can be connected to the flexible surface via a section of optic fibre containing the fibre grating element. This connection may be by several methods.
  • the optic fibre section can be supported on the flexible surface.
  • the optic fibre section can also be bonded to or embedded in the flexible surface.
  • the first and second beams can be made of flexible material.
  • the two beams are made of mechanically flexible material.
  • the first and second beams can have the same coefficients of thermal expansion.
  • the first and second beams can also be relatively thin.
  • Fig.1 is a perspective view of a temperature compensation package for a fibre grating element according to a preferred embodiment of the invention
  • Fig. 2 is a top view of the package of Fig. 1 ;
  • Fig. 3 is a perspective view of an alternative embodiment of the temperature compensation package of Fig. 1;
  • Fig. 4 is a top view of the package of Fig. 3;
  • Fig. 5 is a perspective view of another embodiment of the temperature compensation package of Fig. 1;
  • Fig. 6 is a perspective view of a further embodiment of the temperature compensation package of Fig. 1;
  • Figs. 7A, 7B and 7C are top views of the first beam, second beam and the fibre grating element mounted on the first beam, respectively, of the package of Fig.1.
  • Figs. 1 and 2 show a temperature compensation package 1 according to a preferred embodiment of the invention.
  • Package 1 has a first beam 11, a second beam 22 and control means 44.
  • Beams 11, 22 are made from thin, flexible material and are arcuate in shape. Beams 11 , 22 are bonded at their respective ends 55, 66 using suitable bonding material, such as an epoxy agent.
  • a section of optic fibre 33 containing a fibre grating element 13 is located in grooved surface 12 of flexible beam 11.
  • Surface 12 is, by virtue of being integrally formed with flexible beam 11, connected to grating element 13 via fibre section 33 so as to transmit force to grating element 13.
  • Surface 12 acts as a member that can be flexed to adjust the force transmitted to the grating element 13.
  • the width of first beam 11 is larger than the width of second beam 22 to allow surface 12 to flex (and so apply force to fibre grating element 13) unhindered by any contact with second beam 22.
  • Control means 44 is centrally located between beams 11 , 22 and controls the flexing of surface 12 of beam 11. Other locations are possible in between the two ends of the beams 11, 22.
  • Control means 44 in this embodiment is a cylindrical bulk strain adjustment member which is responsive to changes in temperature.
  • control means 44 can be an actuator which actively controls flexing of surface 12 on beam 11.
  • the strain adjustment member 44 can made from metal and glass materials with large coefficients of thermal expansion.
  • strain adjustment member 44 has a large positive coefficient of thermal expansion. Strain adjustment member 44 is bonded to respective interface surfaces 24 of the first beam 11 and the second beam 22. The sizes of the interface surfaces 24 vary with the cross- sectional area of the strain adjustment member 44.
  • the package 1 operates as follows. As the adjustment member 44 is inserted between beams 11, 22, a compression strain is applied to beams 11, 22, causing them to flex or bend in an arcuate shape. Surface 12 also flexes, transmitting this compression strain force to optic fibre section 33 and grating element 13. As the temperature of the package 1 increases, the length of the adjustment member 44 expands. This causes adjustment member 44 to apply further compression against beams 11 and 22. This is transmitted by surface 12 to fibre section 33 and grating element 13, causing further compression of grating element 13. This increased compression strain on grating element 13 compensates for the effect of the increasing temperature. Thus, the central wavelength of the fibre grating element 13 is held constant against the increase in temperature.
  • the adjustment member 44 contracts, reducing the flexure on beam 11 and so surface 12. This reduction in force is transmitted by surface 12 to grating element 13, relieving the compression strain on the grating element 13. Thus, the central wavelength of the grating is shifted to a longer wavelength thereby compensating for the effect of the decreasing temperature.
  • Figs. 3 and 4 illustrate an alternative embodiment of the package of Fig. 1.
  • adjustment member 44' has a negative coefficient of thermal expansion and optic fibre section 33' containing fibre grating element 13' is located on the underside surface 12' of flexible beam 11'. That is, the flexible surface 12' connecting grating element 13' is on the opposing face of beam 11' to the face of adjustment member 44'.
  • Fig. 5 illustrates another embodiment of the invention.
  • the width of beams 11", 22" are the same.
  • holes 7", 8" are provided in beam 22" to allow optic fibre section 33" to pass through the package 1".
  • adjustment member 44" is located near fibre section 33" and grating element 13".
  • Fig. 6 illustrates a further embodiment of the invention.
  • package 10 is designed to cater for multiple optic fibre sections 33, 34, 35, 36, 37, 38, 39, 40 each containing fibre grating elements 13.
  • the adjustment member 44 has a large coefficient of thermal expansion to provide sufficient force to be transmitted to each fibre grating element 13. While this embodiment is illustrated with an adjustment member 44 having a positive coefficient of thermal expansion, a similar package for multiple optic fibre sections can be made using an adjustment member with a negative coefficient of thermal expansion.
  • Figs. 7A, 7B and 7C shows in more detail the individual components of the package 1.
  • Figs. 7A and 7B show top views of the first beam 11 and the second beam 22, respectively.
  • a thickness and width of less than 2mm and 5mm, respectively, for the beam 11 is preferred.
  • multiple optic fibre sections (33, 34, 35, 36, 37, 38, 39, 40) each containing the grating elements 13 are to be packaged, the width of the beam 11 should be large enough to support these multiple fibre sections.
  • Fig. 7C shows a top view of first beam 11 with optic fibre section 33 containing the grating element 13 embedded in surface 12 of the beam 11.
  • Fibre section 33 is embedded into surface 12 by heat-cured epoxy or other epoxy 13.
  • the fibre section 33 containing the grating element 13 is usually held in tension during the bonding process.
  • the ends 55, 66 connecting the first beam 11 and the second beam 22 can also be joined by laser welding, chemical bonding or mechanical bonding.
  • chemical bonding epoxies can be used while for mechanical bonding, bolts and nuts are used.
  • the first beam 11 and second beam 22 each can have a polygonal cross- section, including a rectangular, square, circular or triangular.
  • the first and second beams need not have the same polygonal cross-section.
  • the first and second beams can be made of any suitable metal, glass or other materials. In the preferred embodiments, for example, beams 11 and 22 are made of Invar metal.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)

Abstract

La présente invention concerne un boîtier (1) à compensation de température pour un élément de réseaux de fibres (13), comprenant un corps (12) relié audit élément de réseaux de fibres (13) pour transmettre une force à cet élément (13), ledit corps (12) étant conçu pour être fléchi afin d'ajuster la force transmise à cet élément de réseaux de fibres (13), et un moyen (44) servant à régler le fléchissement de ce corps (12). Ce moyen de réglage (44) peut être situé entre un premier faisceau (11) et un second faisceau (22) du boîtier (1).
PCT/SG2002/000164 2001-07-26 2002-07-24 Boitier a compensation de temperature pour reseaux de fibres optiques WO2003010577A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SG0104533-5 2001-07-26
SG200104533A SG105503A1 (en) 2001-07-26 2001-07-26 A temperature compensation package for optic fibre gratings

Publications (1)

Publication Number Publication Date
WO2003010577A1 true WO2003010577A1 (fr) 2003-02-06

Family

ID=20430806

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SG2002/000164 WO2003010577A1 (fr) 2001-07-26 2002-07-24 Boitier a compensation de temperature pour reseaux de fibres optiques

Country Status (2)

Country Link
SG (1) SG105503A1 (fr)
WO (1) WO2003010577A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5841920A (en) * 1997-03-18 1998-11-24 Lucent Technologies Inc. Fiber grating package
US6044189A (en) * 1996-12-03 2000-03-28 Micron Optics, Inc. Temperature compensated fiber Bragg gratings
WO2000048027A1 (fr) * 1999-02-12 2000-08-17 Jds Uniphase Corporation Procede et appareil permettant la regulation thermique de dispositifs a reseau de bragg

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6044189A (en) * 1996-12-03 2000-03-28 Micron Optics, Inc. Temperature compensated fiber Bragg gratings
US5841920A (en) * 1997-03-18 1998-11-24 Lucent Technologies Inc. Fiber grating package
WO2000048027A1 (fr) * 1999-02-12 2000-08-17 Jds Uniphase Corporation Procede et appareil permettant la regulation thermique de dispositifs a reseau de bragg

Also Published As

Publication number Publication date
SG105503A1 (en) 2004-08-27

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