JP2008145807A - Fiber bragg grating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an FBG device that can suppress property variation of an optical fiber element caused by change in environmental temperature while preventing destruction of a thermo-module. <P>SOLUTION: The FBG device includes: an optical fiber element 3 containing FBG; a mounting plate 4 for covering the outer periphery of this element; a housing 5; a plate holder 6 for holding the mounting plate 4 in the housing 5; a thermo-module 7 for heating and cooling the optical fiber element 3 in the housing 5; a first stress relaxing layer 8 held between the thermo-module 7 and the plate holder 6; a second stress relaxing layer 9 held between the inner face of the housing 5 and the thermo-module 7; a first temperature sensor 10 for detecting the temperature of the optical fiber element 3 in the housing 5; a second temperature sensor 11 for measuring environmental temperature; and a temperature controller 2 for controlling the operation of the thermo-module 7 on the basis of the detection value of the first and second temperature sensors 10, 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fiber Bragg grating device having an optical fiber element having a fiber Bragg grating (FBG) structure and a thermo module.

  A superstructure FBG (SSSFBG) having a multipoint phase shift structure can be used as an encoder or a decoder in phase code system OCDM (optical code division multiplexing). The SSFBG includes an interval (interval 0) corresponding to a code constituting a plurality of unit FBG structures having the same length and the same period of the refractive index change region (that is, having the same reflection wavelength) in the optical fiber. ) And the number of the optical fiber elements formed. In the OCDM encoder and the OCDM decoder that form a pair, even if the wavelength difference between the two is only a few pm, the OCDM decoder cannot perform decoding. Therefore, the wavelengths of the OCDM encoder and the OCDM decoder that form a pair need to be matched with high accuracy.

  However, the FBG is a device in which a refractive index change region (grating) is formed in a lattice shape in the core of the optical fiber, and the refractive index of the FBG has temperature dependence. Therefore, the reflection wavelength of the FBG largely fluctuates with changes in the environmental temperature.

  In Japanese translation of PCT publication No. 2000-503415 (Patent Document 1), FBG is fixed on a plate-shaped glass ceramic substrate having a negative thermal expansion coefficient, thereby changing the reflection wavelength of FBG caused by changes in environmental temperature. Suppression techniques have been proposed. However, with this technique, it is difficult to precisely control the amount of wavelength variation required for the OCDM encoder and the OCDM decoder.

  Japanese Patent Laying-Open No. 2005-173246 (Patent Document 2) proposes a technique for suppressing fluctuations in reflection wavelength caused by changes in environmental temperature by heating or cooling SSFBG.

Special Table 2000-503415 JP 2005-173246 A

  If the code length is increased in order to provide higher communication security in the phase code method OCDM, the number of unit FBGs constituting the SSFBG increases, so that the total length of the SSFBG becomes longer. Since the SSFBG is composed of the unit FBGs having the same length and the same refractive index change region period, a predetermined encoding or decoding operation cannot be performed unless the individual unit FBGs exhibit the same reflection characteristics. That is, in order for the unit FBGs constituting the SSFBG to exhibit the same reflection characteristics, the temperature needs to be uniform throughout the SSFBG formation region. The encoder or the decoder disclosed in Patent Document 2 can cope with such a requirement by increasing (longening) the thermo module serving as the heating or cooling source of the SSFBG. However, if the thermo module is made larger, the thermal expansion coefficient of the thermo module is different from that of the base plate that directly controls temperature control and the housing that radiates heat, and therefore the contact surface of the thermo module (with the base plate) by repeated heating and cooling. The contact surface or the contact surface with the housing may be destroyed.

  Therefore, the present invention has been made to solve the above-described problems of the prior art, and can prevent fluctuations in the characteristics of the optical fiber element due to changes in the environmental temperature while preventing destruction of the thermomodule. An object is to provide a fiber Bragg grating device.

  The fiber Bragg grating device of the present invention includes an optical fiber element including a fiber Bragg grating, a mounting plate that covers an outer periphery of the optical fiber element, a housing that houses the optical fiber element covered with the mounting plate, A plate holder for holding the mounting plate in the housing, a thermo module for heating and cooling the optical fiber element in the housing, and a first sandwiched between the thermo module and the plate holder A stress relaxation layer, a second stress relaxation layer sandwiched between the inner surface of the housing and the thermo module, and a first temperature sensor for detecting the temperature of the optical fiber element in the housing. It is what you have.

  According to the fiber Bragg grating device of the present invention, it is possible to obtain an effect that the characteristic variation of the optical fiber element due to the change of the environmental temperature can be suppressed while the destruction of the thermo module is prevented.

<< 1. Description of configuration >>
FIG. 1 is a schematic configuration diagram of a fiber Bragg grating (FBG) device according to an embodiment of the present invention, and includes a cross-sectional structure of an FBG package 1. 2 is a cross-sectional view taken along line S ₂ -S ₂ of the FBG package 1 shown in FIG. The FBG device according to the embodiment of the present invention is, for example, an OCDM encoder module or an OCDM decoder module.

  As shown in the figure, the FBG device according to the embodiment has an FBG package 1 and a temperature controller 2 electrically connected to the FBG package 1.

  The FBG package 1 includes an optical fiber element 3 including the FBG, a mounting plate 4 that covers the outer periphery of the optical fiber element 3, and a housing 5 that houses the optical fiber element 3 covered with the mounting plate 4. . The FBG package 1 includes a plate holder 6 that holds the mounting plate 4 in the housing 5, a thermo module 7 that performs at least one of heating and cooling of the optical fiber element 3 in the housing 5, and a thermo module 7. A first stress relaxation layer 8 sandwiched between the plate holder 6 and a second stress relaxation layer 9 sandwiched between the inner surface of the housing 5 and the thermo module 7 are provided. Further, the FBG package 1 includes a first temperature sensor 10 that detects the temperature of the optical fiber element 3 in the housing 5, and a second temperature sensor 11 that detects the environmental temperature of the place where the FBG package 1 is installed. have.

  The optical fiber element 3 is an optical fiber device in which SSFBG is formed on the fiber core.

The mounting plate 4 is made of, for example, invar. However, the mounting plate 4 can be made of a low thermal expansion material such as glass ceramic. The mounting plate 4 is preferably made of a material having a thermal expansion coefficient of 1.2 × 10 ⁻⁶ / K or less. The mounting plate 4 is a columnar member in which a hole for penetrating the optical fiber element 3 or a groove for fixing the optical fiber element 3 is formed.

  The plate holder 6 is made of, for example, copper. However, the plate holder 6 can also be comprised with other materials with large heat conductivity, such as aluminum. The plate holder 6 is preferably made of a material having a thermal conductivity of 200 W / (m · K) or more.

  The mounting plate 4 passes through the through hole of the plate holder 6. The mounting plate 4 and the plate holder 6 are in close contact with each other through silicon grease, and not only the heat conduction efficiency between the mounting plate 4 and the plate holder 6 is improved, but also the lubricity between them is improved. Further, a positioning projection (not shown) is formed on one side surface of the central portion of the mounting plate 4 in the longitudinal direction, and the plate holder 6 is engaged with the positioning projection of the mounting plate 4. A recess (not shown) is formed. The concave portion of the plate holder 6 is formed to be larger than the positioning convex portion of the mounting plate 4, and is formed so that a gap of at least 0.5 mm is formed on both sides in the longitudinal direction of the positioning convex portion. The movable range of the mounting plate 4 with respect to the plate holder 6 is limited by the concave portion of the plate holder 6 and the convex portion for positioning the mounting plate 4.

  The thermo module 7 is a heating and / or cooling module using a Peltier element. When the thermo module 7 heats the plate holder 6, the surface 7 a on the plate holder 6 side of the thermo module 7 becomes the temperature control surface (heat dissipating surface) of the thermo module 7, and the opposite surface (that is, the housing). The surface 7 b facing the inner surface of the body 5 is the heat absorbing surface of the thermo module 7. Further, when the thermo module 7 cools the plate holder 6, the surface 7 a on the plate holder 6 side of the thermo module 7 becomes the temperature control surface (heat absorption surface) of the thermo module 7, and the opposite surface (that is, the surface) The surface 7 b facing the inner surface of the housing 5 is the heat radiating surface of the thermo module 7. The thermo module 7 preferably has a size facing the SSFBG formation region of the optical fiber element 3 and is not smaller than the SSFBG formation region.

  As shown in FIG. 1, the plate holder 6 is fixed to the cir module 7 via the first stress relaxation layer 8. The thermo module 7 is fixed to the bottom surface inside the housing 5 through the second stress relaxation layer 9. When the plate holder 6 is heated or cooled by the thermo module 7, the first stress relaxation layer 8 and the second stress relaxation layer 9 are different from each other in the difference in thermal expansion coefficient between the thermo module 7 and the plate holder 6 and the thermo module 7. It has a function of relieving stress generated in the thermo module 7 due to the difference in thermal expansion coefficient of the housing 5. The thicknesses of the first stress relaxation layer 8 and the second stress relaxation layer 9 are in the range of 50 μm to 200 μm, respectively.

  FIG. 3 is a side view showing an example of the structure of the first stress relaxation layer 8 and the second stress relaxation layer 9 shown in FIG. As shown in FIG. 3, the first stress relaxation layer 8 and the second stress relaxation layer 9 include, for example, a multilayer structure having a buffer material 13 and adhesive layers 12 and 14 provided on both sides thereof. can do.

  FIG. 4 is a side view showing another example of the structure of the stress relaxation layer of the first stress relaxation layer 8 and the second stress relaxation layer 9 shown in FIG. As shown in FIG. 4, the first stress relaxation layer 8 and the second stress relaxation layer 9 are, for example, a single-layer adhesive material layer made of an adhesive material having a function as a buffer material. be able to.

  The 1st stress relaxation layer 8 and the 2nd stress relaxation layer 9 can be comprised with materials, such as an acryl type and a urethane type. However, the first stress relaxation layer 8 and the second stress relaxation layer 9 are not limited to these materials, and other materials may be used. The first stress relaxation layer 8 and the second stress relaxation layer 9 are desirably made of a material having excellent stretchability that expands or contracts by 10% or more in a direction (plane direction) parallel to the surface of each layer. Further, it is desirable that the first stress relaxation layer 8 and the second stress relaxation layer 9 have a thermal conductivity coefficient in the plane direction and the thickness direction of 1 W / m · K or more. Furthermore, it is desirable that the adhesive strength against 180-degree peeling of the first stress relaxation layer 8 and the second stress relaxation layer 9 is 5 N / cm or more, and the shear holding force is 0.1 mm with respect to 1 kg load. It is desirable to be less than.

  Moreover, the 1st temperature sensor 10 and the 2nd temperature sensor 11 which are shown by FIG. 1 are comprised from the thermistor, for example. However, the 1st temperature sensor 10 and the 2nd temperature sensor 11 are not limited to a thermistor, For example, you may use other temperature sensors, such as a thermocouple and a platinum thermal resistor.

  For example, the first temperature sensor 10 is embedded in the mounting plate 10, but may be installed at other positions, such as embedded in the surface of the mounting plate 4, the upper surface or the side surface of the plate holder 6. Good. A plurality of first temperature sensors 10 may be provided such as both ends of the optical fiber element 3.

  The second temperature sensor 11 is preferably installed on the outer surface of the housing 5, for example. However, the second temperature sensor 11 may be installed at another position such as on a substrate (not shown) on which the housing 5 is installed. A plurality of second temperature sensors 11 may be provided. Further, the installation position of the second temperature sensor 11 is not limited to the illustrated example.

  The temperature controller 2 records reference data based on characteristics of the FBG device (for example, characteristics as a phase encoder / decoder). The temperature controller 2 is connected to the first temperature sensor 10, the second temperature sensor 11, and the thermo module 7, and according to the detected temperatures of the first temperature sensor 10 and the second temperature sensor 11, Control the operation of the module. More specifically, the temperature controller 2 controls the operation of the thermomodule 7 so as to bring the temperature of the optical fiber element 3 close to a predetermined set temperature in accordance with the temperature detected by the first temperature sensor 10. Further, the temperature controller 2 controls the heating intensity or the cooling intensity of the thermomodule 7 using data stored in advance, preferably table data, according to the temperature detected by the second temperature sensor 11. The control based on the temperature detected by the second temperature sensor 11 preliminarily influences the expansion or contraction of the housing 5 due to the change in the environmental temperature, the temperature difference in the optical fiber element 3 due to the change in the environmental temperature, and the like. It is used to correct based on the data held, preferably table data.

  FIG. 5 is an explanatory diagram showing an example of the SSFBG structure formed in the optical fiber element shown in FIG. 1, and shows an SSFBG when a 15-bit M-sequence is used as a code string. The optical fiber element 3 is obtained by forming an SSFBG having a multipoint phase shift structure on a single mode optical fiber in which, for example, germanium or the like is added to an optical fiber core to improve ultraviolet sensitivity. In FIG. 5, each of the unit FBGs indicated by the symbols ‘A’ to ‘O’ has the same length and the same refractive index modulation region period. Here, between the units FBG'C 'and' D ', between the units FBG'G' and 'H', between the units FBG'H 'and' I ', and between the units FBG'I' and 'J'. , Between the units FBG 'J' and 'K', between the units FBG 'L' and 'M', and between the units FBG 'N' and 'O', when the wavelength of the optical carrier is λ An interval corresponding to / 4 is provided, and the unit FBGs are arranged with an interval of 0 (zero) between the other unit FBGs, that is, adjacent unit FBGs are arranged in close contact with each other. means. Since the interval corresponding to λ / 4 is the interval corresponding to the phase π / 2 of the optical carrier wave, for example, when an optical pulse is incident from the left side (unit FBG′A ′ side) of FIG. 5, the unit FBG′A The reflected pulses in units FBG'D ',' E ',' F ', and' G 'are π-shifted in phase with respect to the reflected pulses at', 'B', and 'C'. Become.

  The optical fiber element 3 is bonded and fixed at both ends of the mounting plate 4 in a state where no stress such as tensile tension or compressive force is applied, and is in close contact with the mounting plate 4. The SSFBG is included between the adhesive fixing points to the mounting plate 4. The adhesive fixing to the mounting plate 4 of the optical fiber device in the present embodiment uses an ultraviolet curable acrylic adhesive (manufactured by Summers Optical, product number: VTC-2), but is not limited thereto. In addition, an epoxy-based adhesive can also be used.

  The casing 5 is made of, for example, aluminum whose surface is plated with gold. However, the material of the case 5 is not limited to this, and the housing 5 can be made of another material that is inexpensive and easy to process, such as copper. The housing 5 is preferably made of a material having a thermal conductivity of 230 W / (m · K) or more. The housing 5 has a box shape, and has a power supply terminal to the thermo module 7 included in the SSFBG mounting portion and an output terminal from the first temperature sensor 10 on its side surface. It is connected to the temperature controller 2 through these terminal portions, and heating or cooling of the thermo module 7 is controlled.

<< 2. Explanation of operation >>
Next, the contents of control by the temperature controller 2 will be described. Based on the temperature set by the temperature controller 2, according to the difference between the set value and the temperature measured by the first temperature sensor 10, the temperature controller 2 determines that the temperature measured by the first temperature sensor 10 is the set value. The heating or cooling of the thermo module 7 is controlled to be equal. The mounting plate 4 is kept at a constant temperature via the plate holder 6 by the control of the thermo module 7 by the temperature controller 2. Here, the mounting plate 4 is heated or cooled by heat conduction from the plate holder 6 heated or cooled by the thermo module 7. However, since the plate holder 6 made of a high heat conductive material covers the mounting plate 4, the mounting plate 4 is mounted. Generation of a temperature distribution in the longitudinal direction of the plate 4 (increase in temperature difference) is suppressed.

  Further, the temperature controller 2 controls the heating intensity or the cooling intensity of the thermomodule 7 using data held in advance, preferably table data, according to the temperature detected by the second temperature sensor 11. By this control, it is possible to reduce the influence of expansion or contraction of the housing 5 due to the change in the environmental temperature, temperature difference in the optical fiber element 3 due to the change in the environmental temperature, and the like. However, the control based on the second temperature sensor 11 and the second temperature sensor 11 is not necessarily required when the FBG device of the present invention is installed in a place where there is no environmental change.

  In addition, since the plate holder 6 and the mounting plate 4 are not mechanically fixed but are in close contact with each other through silicon grease, the expansion and contraction of the plate holder 6 caused by heating or cooling by the thermo module 7 is applied to the mounting plate 4. Is not transmitted. Further, since the mounting plate 4 is made of a low thermal expansion material, the mounting plate 4 itself does not expand or contract. Since the SSFBG included in the optical fiber element 3 is fixed to the mounting plate 4, only the temperature of the SSFBG changes with the temperature change of the mounting plate 4, and the reflection wavelength of the SSFBG can be controlled only by the temperature. .

  Next, the case where the mounting plate 4 is heated by the thermo module 7 (that is, the wavelength is adjusted to the long wavelength side) is taken as an example, and the first stress relaxation layer 8 and the second stress relaxation layer 8 used for fixing the thermo module 7 are used. The thermal stress relaxation operation by the stress relaxation layer 9 will be described.

  FIG. 6 is an explanatory diagram of the stress generated in the thermo module of the conventional FBG device when the plate holder is heated, and FIG. 7 is the thermo module of the FBG device according to the embodiment of the present invention when the plate holder is heated. It is explanatory drawing of the stress which generate | occur | produces.

  When the mounting plate 4 is heated, the temperature between the surface (heat absorption surface) 7b on the housing 5 side of the thermo module 7 and the temperature control surface (heat generation surface) 7a on the plate holder 6 side of the thermo module 7 is increased by heat transfer. There is a difference. In general, the ceramic forming the surface of the thermo module 7 has a smaller coefficient of thermal expansion than copper forming the plate holder 6 on the heat generation side or aluminum forming the housing 5 on the heat absorption side. For this reason, as shown in FIG. 6, the expansion / contraction amount accompanying the temperature change of the plate holder 6 or the housing | casing 5 and the expansion / contraction amount accompanying the temperature change of the thermomodule 7 surface differ. At this time, as shown in FIG. 6, if the thermo module 7 and the plate holder 6 or the housing 5 are firmly fixed, an internal stress is generated in the thermo module 7, and the Peltier element itself or the solder to the electrode is soldered. There is a possibility that the thermo module 7 may be broken due to the difference in the amount of expansion and contraction at the attachment portion.

  On the other hand, when the thermo module 7 is fixed via the first stress relaxation layer 8 and the second stress relaxation layer 9 as in the case of the present invention shown in FIG. 7, the surface of the thermo module 7, the mounting plate 4, and the housing. Since the first stress relaxation layer 8 and the second stress relaxation layer 9 absorb and contract the difference in expansion and contraction with the body 5 in the plane direction, the generation of stress can be suppressed and the thermo module 7 can be prevented from being broken. be able to. Furthermore, since the first stress relaxation layer 8 and the second stress relaxation layer 9 are excellent in heat conduction and are sufficiently thin, the control module and the mounting plate 4 between the thermo module 7 and the heat dissipation surface of the thermo module 7 There is no thermal resistance in the heat conduction between the casings 5, and the temperature control of the SSFBG by the thermo module 7 is not hindered.

<< 3. Explanation of effects >>
As described above, by using the fixing method of the thermo module 7 in the FBG device according to the embodiment of the present invention, for example, the number of parts such as screws and heat insulating materials for fixing the plate holder 6 can be reduced. In addition, it is possible to reduce processing steps such as omitting the screw hole processing of the housing 5, and to reduce the cost and time for manufacturing.

  Further, according to the FBG device of the embodiment of the present invention, an OCDM encoder module capable of performing adjustment to an arbitrary wavelength with high wavelength adjustment resolution can be realized at a low cost and with a simple configuration. The wavelength can be adjusted with high accuracy without being affected by the manufacturing error of the included SSFBG.

<< 4. Modifications >>
In the above description, the case where the FBG device is an OCDM encoder module or an OCDM decoder module has been described. However, the FBG device of the present invention is not limited to these. The FBG device of the present invention can also be applied to, for example, an encoder or decoder in wavelength hopping OCDM, a filter device in a WDM system, etc., and obtains the same effect as when the FBG device is an OCDM encoder module Can do.

  Further, the drawings used in the above description show one configuration example of the apparatus to which the present invention is applied, and only schematically show the cross-sectional shape and arrangement relationship of each component to the extent that the invention can be understood. The invention is not limited to the illustrated example.

  Furthermore, in the above description, specific materials, conditions, dimensions, etc. are illustrated, but these materials, conditions, dimensions, etc. show one of preferred examples, and the present invention is not limited to these. It is not something.

It is a schematic block diagram of the FBG apparatus of embodiment of this invention. FIG. ₂ is a cross-sectional view of the FBG package shown in FIG. 1 taken along line S ₂ -S ₂ . It is a side view which shows an example of the structure of the 1st and 2nd stress relaxation layer shown by FIG. It is a side view which shows the other example of the structure of the 1st and 2nd stress relaxation layer shown by FIG. It is explanatory drawing which shows an example of the SSFBG structure formed in the optical fiber element shown by FIG. It is explanatory drawing of the stress which generate | occur | produces in the thermo module of the conventional FBG apparatus at the time of plate holder heating. It is explanatory drawing of the stress which generate | occur | produces in the thermo module of the FBG apparatus of embodiment of this invention at the time of plate holder heating.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 FBG package, 2 Temperature controller, 3 Optical fiber element, 4 Mounting plate, 5 Case, 6 Plate holder, 7 Thermo module, 7a Surface on the plate holder side of thermo module, 7b Surface on the housing side of thermo module, 8 No. 1 stress relaxation layer, 9 second stress relaxation layer, 10 first temperature sensor, 11 second temperature sensor, 12, 14 adhesive layer, 13 buffer material.

Claims (16)

An optical fiber element including a fiber Bragg grating;
A mounting plate covering the outer periphery of the optical fiber element;
A housing for housing the optical fiber element covered with the mounting plate;
A plate holder for holding the mounting plate in the housing;
A thermo module that performs at least one of heating and cooling of the optical fiber element in the housing;
A first stress relaxation layer sandwiched between the thermo module and the plate holder;
A second stress relaxation layer sandwiched between the inner surface of the housing and the thermo module;
A fiber Bragg grating device comprising: a first temperature sensor that detects a temperature of the optical fiber element in the housing.   And a temperature controller for controlling heating or cooling by the thermo module so that the temperature of the optical fiber element in the housing approaches a predetermined temperature based on the temperature detected by the first temperature sensor. The fiber Bragg grating device according to claim 1, wherein   The fiber Bragg grating device according to claim 1, further comprising a second temperature sensor that detects an environmental temperature of a place where the fiber Bragg grating device is installed.   The fiber Bragg grating device according to claim 3, wherein the second temperature sensor is disposed on an outer periphery of the housing.   Based on the temperature detected by the first temperature sensor, the heating or cooling by the thermo module is controlled so that the temperature of the optical fiber element in the housing approaches a predetermined temperature, and the second temperature is controlled. The fiber Bragg grating device according to claim 3, further comprising a temperature controller that controls heating or cooling by the thermo module based on a temperature detected by a sensor.   Control of heating or cooling by the thermo module based on the temperature detected by the second temperature sensor by the temperature controller is executed using table data held in advance by the temperature controller. The fiber Bragg grating device according to claim 5.   The fiber Bragg grating device according to any one of claims 1 to 6, wherein the fiber Bragg grating is a superstructure fiber Bragg grating having a plurality of unit fiber Bragg grating structures.   The fiber Bragg grating device according to claim 7, wherein the optical fiber element is an OCDM encoder or an OCDM decoder. The expansion / contraction ratio of the first stress relaxation layer and the second stress relaxation layer in the direction parallel to the surface of the first stress relaxation layer and the second stress relaxation layer contacting the thermo module is 10 % Or more,
The fiber Bragg grating according to any one of claims 1 to 8, wherein a thermal conductivity coefficient of the first stress relaxation layer and the second stress relaxation layer is 1 W / m · K or more. apparatus. The first stress relaxation layer has adhesiveness on each surface that contacts the thermo module and the plate holder,
The fiber Bragg grating according to any one of claims 1 to 9, wherein the second stress relaxation layer has adhesiveness on an inner surface of the casing and on each surface contacting the thermo module. apparatus. The adhesive strength of the first stress relaxation layer and the second stress relaxation layer is 5 N / cm or more in a 180 degree peel test,
The fiber Bragg grating device according to claim 10, wherein a shear holding force of the first stress relaxation layer and the second stress relaxation layer is less than 0.1 mm with respect to a 1 kg load.   The fiber Bragg grating device according to any one of claims 1 to 11, wherein the first stress relaxation layer and the second stress relaxation layer are made of an acrylic or urethane material. .   13. The fiber Bragg grating according to claim 1, wherein thicknesses of the first stress relaxation layer and the second stress relaxation layer are within a range of 50 μm to 200 μm. apparatus.   In the thermo module, the first stress relaxation layer side absorbs heat when the second stress relaxation layer side generates heat, and the first stress relaxation layer absorbs heat when the second stress relaxation layer side absorbs heat. The fiber Bragg grating device according to any one of claims 1 to 13, wherein the layer side is a Peltier module that generates heat. The mounting plate is made of a material having a coefficient of thermal expansion of 1.2 × 10 ⁻⁶ / K or less,
The fiber Bragg grating device according to any one of claims 1 to 14, wherein the plate holder is made of a metal material having a thermal conductivity of 200 W / (m · K) or more. The mounting plate is invar or glass ceramic,
The fiber Bragg grating device according to claim 15, wherein the plate holder is made of copper or aluminum.

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