WO2020059433A1 - Optical fiber cooling device and optical fiber laser device - Google Patents

Optical fiber cooling device and optical fiber laser device Download PDF

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Publication number
WO2020059433A1
WO2020059433A1 PCT/JP2019/033296 JP2019033296W WO2020059433A1 WO 2020059433 A1 WO2020059433 A1 WO 2020059433A1 JP 2019033296 W JP2019033296 W JP 2019033296W WO 2020059433 A1 WO2020059433 A1 WO 2020059433A1
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Prior art keywords
optical fiber
cooling device
liquid metal
cooling
laser
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PCT/JP2019/033296
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French (fr)
Japanese (ja)
Inventor
大介 小西
政直 村上
亮 安原
Original Assignee
三星ダイヤモンド工業株式会社
大学共同利用機関法人自然科学研究機構
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Application filed by 三星ダイヤモンド工業株式会社, 大学共同利用機関法人自然科学研究機構 filed Critical 三星ダイヤモンド工業株式会社
Priority to CN201980061610.3A priority Critical patent/CN112740489A/en
Priority to JP2020548204A priority patent/JPWO2020059433A1/en
Publication of WO2020059433A1 publication Critical patent/WO2020059433A1/en

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    • 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
    • G02B6/24—Coupling light guides
    • G02B6/255—Splicing of light guides, e.g. by fusion or bonding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/02—Constructional details
    • H01S3/04—Arrangements for thermal management
    • H01S3/042—Arrangements for thermal management for solid state lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers

Definitions

  • the present invention relates to an optical fiber cooling device and an optical fiber laser device.
  • An optical fiber laser device is a device that oscillates or amplifies laser light by inputting excitation light from an excitation light source such as a semiconductor laser to a laser medium such as a rare earth ion added to the core of an optical fiber.
  • an excitation light source such as a semiconductor laser
  • a laser medium such as a rare earth ion added to the core of an optical fiber.
  • the laser active substance contained in the optical fiber generates heat by absorbing the excitation light. Since the conversion efficiency from the excitation light to the laser light changes due to this heat generation, it is desirable to keep the temperature of the optical fiber constant in order to stably output the laser light.
  • the optical fiber device generally has a cooling device (for example, see Patent Document 1).
  • the optical fiber cooling device described in Patent Literature 1 the optical fiber is brought into close contact with a heat sink via a metal heat radiating member.
  • metals such as copper and aluminum are excellent in heat conduction as heat dissipating members, but since they are solid, they need to be processed according to the shape of the object to be cooled.
  • solid metal is required to have high processing accuracy, there is a possibility that the adhesion may be insufficient. In that case, the optical fiber cannot be cooled efficiently.
  • resin and grease have high adhesiveness but low thermal conductivity, and thus are inferior in cooling performance.
  • An object of the present invention is to improve the cooling performance of an optical fiber cooling device.
  • An optical fiber cooling device includes a storage unit, a liquid metal, and a cooling device.
  • the storage section stores at least a part of the optical fiber.
  • the liquid metal is disposed in the storage section.
  • the cooling device cools the liquid metal. In this device, the performance of cooling the optical fiber is improved. This is because the liquid metal is liquid at room temperature, so that it has excellent adhesion to the optical fiber and good heat conduction (for example, about 27.5 times water). Therefore, the cooling performance of the optical fiber cooling device is improved.
  • the optical fiber may include a first optical fiber, a second optical fiber, and a connection portion between both.
  • the connection part may be stored in the storage part. In this device, the optical fiber is cooled efficiently. This is because the connection portion is the portion that generates the most heat.
  • the optical fiber cooling device may further include a circulation device for returning the liquid metal from the storage unit and returning the same.
  • the cooling device may cool the liquid metal in a part of the circulation device. In this device, the degree of freedom of installation of the cooling device is increased.
  • the liquid metal may include one or more metals selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth. In this device, the performance of cooling the optical fiber is further improved.
  • the liquid metal may comprise an alloy of gallium, indium and tin.
  • the performance of cooling the optical fiber is further improved.
  • An optical fiber laser device includes an optical fiber and the optical fiber cooling device.
  • An optical fiber cooling device is a device for cooling an optical fiber, and includes a storage unit, a liquid metal, and a cooling device.
  • the storage section stores at least a part of the optical fiber.
  • the liquid metal is disposed in the storage section.
  • the cooling device cools the liquid metal by cooling the storage unit from the outside. In this device, the performance of cooling the optical fiber is improved. Because the liquid metal is liquid at room temperature, it has excellent adhesion to the fiber and good heat conduction (for example, about 27.5 times water). Therefore, the cooling performance of the optical fiber cooling device is improved. In particular, since the housing is directly cooled, the structure is simplified, and the cooling effect of the liquid metal is enhanced.
  • the optical fiber may include a first optical fiber, a second optical fiber, and a connection portion between both.
  • the connection part may be stored in the storage part. In this device, the optical fiber is cooled efficiently. This is because the connection portion is the portion that generates the most heat.
  • the storage section may include a metal body and an embrittlement prevention coat.
  • the metal body may have an inner wall surface that forms a space for storing the liquid metal.
  • the embrittlement prevention coat may be formed on the inner wall surface.
  • the embrittlement prevention coat is made of a material that is not eroded by the liquid metal. In this device, since the storage portion is made of metal, heat conduction is good. Therefore, the effect of cooling the liquid metal is enhanced. Further, the metal body of the storage section is protected against the liquid metal by the embrittlement prevention coat. Therefore, embrittlement of the metal body is prevented.
  • the liquid metal may include one or more metals selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth. In this device, the performance of cooling the optical fiber is further improved.
  • the liquid metal may comprise an alloy of gallium, indium and tin.
  • the performance of cooling the optical fiber is further improved.
  • An optical fiber laser device includes an optical fiber and the optical fiber cooling device.
  • the cooling performance is improved.
  • FIG. 1 is a schematic configuration diagram of an optical fiber and an optical fiber cooling device according to a first embodiment. Sectional drawing of a 1st optical fiber (non-doped fluoride fiber). Sectional drawing of the 2nd optical fiber (Er addition fluoride fiber).
  • FIG. 2 is a block diagram showing a control configuration of the optical fiber cooling device.
  • FIG. 5 is a schematic configuration diagram of an optical fiber and an optical fiber cooling device according to a second embodiment.
  • FIG. 2 is a block diagram showing a control configuration of the optical fiber cooling device.
  • FIG. 1 is a schematic configuration diagram of an optical fiber and an optical fiber cooling device.
  • the laser oscillator 1 generally oscillates when excitation light is incident from an excitation light source.
  • the excitation light source oscillates the excitation light, and is, for example, a semiconductor laser.
  • the operation principle of the laser oscillator will be described.
  • pumping light incident from an input end of an optical fiber passes through the core, so that the pumping light is absorbed in the core. Thereafter, light emission is amplified inside the core by stimulated emission, and furthermore, the inside of the optical fiber is repeatedly reflected by mirrors at both ends, thereby leading to laser oscillation from the output end.
  • the laser oscillator 1 has a laser resonator 3 that oscillates a laser beam when the pump light L1 is incident, and an optical fiber cooling device 5 that cools the laser resonator 3.
  • the laser resonator 3 has an optical fiber 15.
  • the optical fiber 15 functions as a laser medium and a resonator, amplifies laser light generated by irradiation with excitation light, and causes laser oscillation.
  • the optical fiber 15 has a first optical fiber 17 and a second optical fiber 19.
  • the first optical fiber 17 has an input end 17d and an output end 17e.
  • the first end cap 25a is connected to the input end 17d.
  • the second optical fiber 19 has an input end 19d and an output end 19e.
  • the output end 17 e of the first optical fiber 17 and the input end 19 d of the second optical fiber 19 are fusion-spliced by the first connection part 21.
  • the second optical fiber 19 forms an annular portion 19f wound a plurality of times.
  • a third optical fiber 20 having the same configuration as that of the first optical fiber 17 is fusion-spliced to an output end 19 e of the second optical fiber 19 by a second connecting portion 22.
  • the first optical fiber 17 has a core 17a, a clad 17b, and a buffer 17c, as shown in FIG. FIG. 2 is a cross-sectional view of the first optical fiber (non-doped fluoride fiber).
  • the first optical fiber 17 is a non-doped fluoride fiber, and is used to propagate the pump light.
  • the core 17a is made of, for example, ZBLAN glass, to which no rare earth is added.
  • the cladding 17b is formed so as to cover the core 17a on the outer periphery of the core 17a, and is a layer having a smaller refractive index than the core 17a.
  • the buffer 17c is a layer for protecting the core 17a and the clad 17b from external stimuli.
  • the second optical fiber 19 is a fluoride fiber doped with a rare earth element.
  • the second optical fiber 19 emits laser light of a mid-infrared wavelength (specifically, around 2.8 ⁇ m) by being excited by the excitation light.
  • the second optical fiber 19 is excited by the excitation light introduced from the input end 19d, and generates a laser beam having a wavelength determined by the substance doped in the second optical fiber 19.
  • the second optical fiber 19 is a double clad fiber, and has a core 19a, a first clad 19b, a second clad 19c, and a buffer 19g.
  • FIG. 3 is a cross-sectional view of the second optical fiber (Er-doped fluoride fiber).
  • the core 19a is a ZBLAN glass doped with erbium (Er) as a rare earth element.
  • ZBLAN glass is a fluoride glass containing zirconium (Zr), barium (Ba), lanthanum (La), aluminum (Al), and sodium (Na) as main components.
  • the additive substance may be any substance as long as the substance oscillates laser, and may be, for example, another rare earth element such as ytterbium (Yb).
  • the first cladding 19b and the second cladding 19c are formed so as to cover the core 19a on the outer periphery of the core 19a, and are layers having a smaller refractive index than the core 19a. Further, the first cladding 19b and the second cladding 19c do not contain a rare earth element.
  • the buffer 19g is a layer for protecting the core 19a, the first clad 19b, and the second clad 19c from external physical pressure.
  • the second optical fiber 19 can mainly convert the pump light into light having a wavelength band of 2.8 ⁇ m. Specifically, in the first cladding 19b, light mainly in the 2.8 ⁇ m wavelength band is reflected and propagated through the core 19a.
  • the excitation light is mainly reflected and propagates through the first cladding 19b and the core 19a.
  • the excitation light passes through the core 19a, absorption occurs, and the light is converted into light in a wavelength band of 2.8 ⁇ m.
  • the annular portion 19f of the second optical fiber 19 is bent at a radius larger than the minimum radius at which light propagating in the core 19a does not leak to the first clad 19b.
  • a high-reflection FBG (Fiber Bragg Grating) 23 and a low-reflection FBG 25 are drawn in the second optical fiber 19.
  • the high reflection FBG 23 is drawn near the input end 19 d of the second optical fiber 19, that is, near the first connection part 21.
  • the low reflection FBG 25 is drawn on the side near the output end 19 e of the second optical fiber 19.
  • the high reflection FBG 23 is a reflection unit that totally reflects light having a specific wavelength to be oscillated as laser light in the laser resonator 3.
  • the low reflection FBG 25 is a reflection unit that transmits only a part of the light having a specific wavelength that is oscillated as laser light in the laser resonator 3 and reflects the rest.
  • the first end cap 25a is light transmissive for transmitting the excitation light and the laser light, and has no deliquescence. Further, the first end cap 25a preferably has a melting point equal to or higher than the melting point of the first optical fiber 17, and the thermal conductivity of the first optical fiber 17 for cooling the end face thereof is lower than that of the first optical fiber 17. It is preferably higher than that.
  • the first end cap 25a preferably has a linear expansion coefficient substantially equal to that of the first optical fiber 17 in order to strengthen the bonding with the first optical fiber 17.
  • the first end cap 25a can be a crystal such as calcium fluoride.
  • the first end cap 25a may be made of other crystal such as quartz.
  • the second end cap 25b has the same configuration as the first end cap 25a.
  • the third optical fiber 20 has a length that is emitted before the laser light is reflected inside. Further, since the third optical fiber 20 is not doped with a rare earth element such as erbium which is a laser medium, it does not generate heat even when excitation light is incident.
  • a rare earth element such as erbium which is a laser medium
  • the laser resonator 3 is formed by the configuration of the optical fiber 15 described above.
  • the light is emitted by being absorbed by the rare earth element doped in the core 19a of the second optical fiber 19, causing a population inversion between the ground level and the metastable level.
  • the light thus emitted oscillates by the light amplifying action of the second optical fiber 19 and the action of the high reflection FBG 23 and the low reflection FBG 25.
  • the output light is output from an output end 19e of the second optical fiber 19.
  • the output light is guided to the dichroic mirror 27.
  • the dichroic mirror 27 transmits the excitation light L2 from the excitation light source, but reflects the laser light L3 without transmitting.
  • the laser beam L3 reflected by the dichroic mirror 27 is used as an output for various purposes.
  • the damper 29 (for example, a device having a function of measuring light output) is disposed downstream of the dichroic mirror 27, and can absorb and measure the excitation light L2 transmitted by the dichroic mirror 27.
  • the output can be monitored by the control device (for example, the control unit 51).
  • the optical fiber cooling device 5 is a device that cools the optical fiber 15 using the cooled liquid metal M.
  • the optical fiber cooling device 5 includes a housing 33 (an example of a storage unit), a circulation device 35, and a chiller device 37 (an example of a cooling device).
  • the housing 33 is a device that is formed in a box shape, holds the second optical fiber 19, and directly cools the second optical fiber 19.
  • the housing 33 has an internal space 33a for accommodating the annular portion 19f of the second optical fiber 19. With this structure, the housing 33 holds the second optical fiber 19.
  • the housing 33 is made of, for example, acrylic. Further, the internal space 33a is filled with the liquid metal M. An annular passage through which the liquid metal M can circulate is formed in the internal space 33a.
  • the circulation device 35 is a device that returns the liquid metal M from the housing 33 and returns it.
  • the circulation device 35 has a pipe 43 and a pump 45.
  • the pipe 43 is connected to an inflow port 33b and an outflow port 33c provided in the internal space 33a of the housing 33.
  • the chiller device 37 cools the liquid metal M flowing through the internal space 33 a of the housing 33 in a part of the circulation device 35.
  • the chiller device 37 cools the liquid metal M in the pipe 43 by using water, for example, by a double pipe structure.
  • the liquid metal M is sent from the internal space 33 a of the housing 33 to the chiller device 37 via the pipe 43 by the pump 45.
  • the liquid metal M is cooled by the chiller device 37. Thereafter, the liquid metal M is returned to the housing 33 via the pipe 43.
  • the liquid metal M includes one or more metals selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth. Specifically, the liquid metal M is made of an alloy of gallium, indium, and tin. The alloy of gallium, indium, and tin has a thermal conductivity of about 16.5 [W / mK]. In this device, since the liquid metal M is liquid at room temperature, it has excellent adhesion to the second optical fiber 19 and good thermal conductivity (for example, about 27.5 times water). Therefore, the cooling performance is improved.
  • the liquid metal M that has absorbed the heat amount does not stay in the internal space 33a, and the heat absorption efficiency can be further improved.
  • Gallium, indium, tin alloy for example, a Ga 14 In 3 Sn 2, Ga 17 In 4 Sn 2, Ga 22 In 4 Sn 3, Ga 25 In 5 Sn 4, Ga 25 In 6 Sn 3.
  • the first connection portion 21 and the input end 19d of the second optical fiber 19 are cooled while being in contact with the liquid metal M, the effect of preventing heat generation is excellent.
  • FIG. 4 is a block diagram showing a control configuration of the optical fiber cooling device.
  • the optical fiber cooling device 5 has a control unit 51.
  • the control unit 51 has a processor (for example, CPU), a storage device (for example, ROM, RAM, HDD, SSD, etc.) and various interfaces (for example, A / D converter, D / A converter, communication interface, etc.). It is a computer system.
  • the control unit 51 performs various control operations by executing a program stored in a storage unit (corresponding to part or all of the storage area of the storage device).
  • the control unit 51 may be configured by a single processor, or may be configured by a plurality of independent processors for each control.
  • a part or all of the functions of each element of the control unit 51 may be realized as a program that can be executed by a computer system configuring the control unit 51.
  • a part of the function of each element of the control unit 51 may be configured by a custom IC.
  • the pump 45 of the circulation device 35 and the chiller device 37 are connected to the control unit 51.
  • the control unit 51 can control these and other devices.
  • sensors and switches for detecting the state of each device and an information input device are connected to the control unit 51.
  • an excitation light source (not shown) emits excitation light.
  • the pump light enters the optical fiber 15, specifically, the input end 17 d of the first optical fiber 17 through the first end cap 25 a.
  • the pump light is sent from the first optical fiber 17 to the second optical fiber 19.
  • the excitation light enters the second optical fiber 19 through the high reflection FBG 23.
  • the active substance in the core 19a is excited by the excitation light, and light is emitted from the active substance.
  • the light emitted from the active substance reciprocates between the high-reflection FBG 23 and the low-reflection FBG 25 while propagating in the core 19a.
  • light having a specific wavelength is emitted as laser light from the second optical fiber 19 through the low-reflection FBG 25 to the outside.
  • the laser light is emitted outside through the third optical fiber 20 and the second end cap 25b.
  • the excitation light L2 passes through the dichroic mirror 27, and is absorbed and measured by the damper 29 (for example, a device having a function of measuring an optical output). Based on this, the control device (for example, the control unit 51) can monitor the output.
  • the control device for example, the control unit 51
  • the laser light L3 generated in the core 19a of the second optical fiber 19 is reflected by the dichroic mirror 27 and output to the outside.
  • the optical fiber 15 generates heat, but the optical fiber 15 is efficiently cooled by the optical fiber cooling device 5. Thereby, the optical fiber 15 can be cooled efficiently and more uniformly, and thereby the cooling efficiency can be improved. Therefore, in the laser oscillator 1, it is possible to prevent a decrease in the output of the laser light, and it is possible to obtain a stable output of the laser light.
  • FIG. 5 is a schematic configuration diagram of the optical fiber and the optical fiber cooling device according to the second embodiment. Note that the structure common to the first embodiment is appropriately omitted.
  • the laser oscillator 101 generally oscillates laser when excitation light is incident from an excitation light source.
  • the excitation light source oscillates the excitation light, and is, for example, a semiconductor laser.
  • the laser oscillator 101 includes the laser resonator 3 that oscillates a laser beam when the pump light L1 is incident, and the optical fiber cooling device 105 that cools the laser resonator 3.
  • the laser resonator 3 has an optical fiber 15.
  • the optical fiber 15 functions as a laser medium and a resonator, amplifies laser light generated by irradiation with excitation light, and causes laser oscillation.
  • optical fiber 15 is the same as that of the first embodiment. Therefore, the description is omitted here.
  • the optical fiber cooling device 105 is a device that cools the optical fiber 15 using the cooled liquid metal M.
  • the optical fiber cooling device 105 includes a housing 133 (an example of a storage unit) and a chiller device 137 (an example of a cooling device).
  • the casing 133 is a box-shaped device that holds the second optical fiber 19 and directly cools the second optical fiber 19.
  • the housing 133 has an internal space 133a that accommodates the annular portion 19f of the second optical fiber 19. With this structure, the second optical fiber 19 is held by the housing 133.
  • the internal space 133a is filled with the liquid metal M.
  • An annular passage through which the liquid metal M can circulate is formed in the internal space 133a.
  • the chiller device 137 cools the liquid metal M staying in the internal space 133a of the housing 133 from outside the housing 133.
  • the performance of cooling the optical fiber 15 is improved. This is because the liquid metal is liquid at room temperature, so that it has excellent adhesion to the optical fiber 15 and good heat conduction (for example, about 27.5 times water). Therefore, the cooling performance of the optical fiber cooling device 105 is improved.
  • the housing 133 is directly cooled, the structure is simplified, and the cooling effect of the liquid metal M is enhanced.
  • the chiller device 137 is in contact with at least one side surface of the housing 133.
  • the chiller device 137 may be in contact with a plurality of side surfaces of the housing 133, or may be in contact with the housing 133 while partially or entirely covering the housing 133.
  • the housing 133 is made of metal, and an embrittlement prevention coat is formed on an inner wall surface of the inner space 133a.
  • the embrittlement prevention coat is, for example, a resin that is cured by heat or UV light, and specifically, is an acrylic resin, an epoxy resin, or a Teflon (registered trademark) resin. Further, the metal body of the storage section is protected against the liquid metal M by the embrittlement prevention coat. Therefore, embrittlement of the metal body is prevented.
  • the liquid metal M includes one or more metals selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth. Specifically, the liquid metal M is made of an alloy of gallium, indium, and tin. The alloy of gallium, indium, and tin has a thermal conductivity of about 16.5 [W / mK]. In this device, since the liquid metal M is liquid at room temperature, it has excellent adhesion to the second optical fiber 19 and good thermal conductivity (for example, about 27.5 times water). Therefore, the cooling performance is improved.
  • Gallium, indium, tin alloy for example, a Ga 14 In 3 Sn 2, Ga 17 In 4 Sn 2, Ga 22 In 4 Sn 3, Ga 25 In 5 Sn 4, Ga 25 In 6 Sn 3.
  • the effect of preventing heat generation is enhanced.
  • FIG. 6 is a block diagram showing a control configuration of the optical fiber cooling device.
  • the optical fiber cooling device 105 has a control unit 51.
  • the control unit 51 has a processor (for example, CPU), a storage device (for example, ROM, RAM, HDD, SSD, etc.) and various interfaces (for example, A / D converter, D / A converter, communication interface, etc.). It is a computer system.
  • the control unit 51 performs various control operations by executing a program stored in a storage unit (corresponding to part or all of the storage area of the storage device).
  • the control unit 51 may be configured by a single processor, or may be configured by a plurality of independent processors for each control.
  • a part or all of the functions of each element of the control unit 51 may be realized as a program that can be executed by a computer system configuring the control unit 51.
  • a part of the function of each element of the control unit 51 may be configured by a custom IC.
  • the chiller device 137 is connected to the control unit 51.
  • the control unit 51 can control these and other devices. Although not shown, sensors and switches for detecting the state of each device and an information input device are connected to the control unit 51.
  • the laser oscillation operation is the same as in the first embodiment. Therefore, the description is omitted here.
  • the optical fiber 15 generates heat, but the optical fiber 15 is efficiently cooled by the optical fiber cooling device 105. Thereby, the optical fiber 15 can be cooled efficiently and more uniformly, and thereby the cooling efficiency can be improved. Therefore, in the laser oscillator 101, it is possible to prevent a decrease in the output of the laser light, and it is possible to obtain a stable output of the laser light.
  • the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the invention.
  • a plurality of embodiments and modifications described in this specification can be arbitrarily combined as needed.
  • the second optical fiber 19 is wound plural times to form an annular shape.
  • the present invention is not limited to this. If so, it may be bent into any shape.
  • optical fiber is not limited to laser oscillation.
  • the internal configuration and the longitudinal configuration of the optical fiber are not limited to those in the above-described embodiment.
  • shape and material of the storage section that stores the fluid metal and the optical fiber are not particularly limited.
  • the present invention is widely applicable to optical fiber cooling devices.

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  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
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  • General Physics & Mathematics (AREA)
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Abstract

This optical fiber cooling device 5 is provided with a housing 33, a liquid metal M, and a chiller device 37. The housing 33 stores a portion of a first optical fiber 17 and a second optical fiber 19. The liquid metal M is disposed inside the housing 33. The chiller device 37 cools the liquid metal M.

Description

光ファイバ冷却装置及び光ファイバレーザ装置Optical fiber cooling device and optical fiber laser device
　本発明は、光ファイバ冷却装置及び光ファイバレーザ装置に関する。 The present invention relates to an optical fiber cooling device and an optical fiber laser device.
　レーザ光の媒体として光ファイバケーブルを用いたレーザ装置、いわゆる光ファイバレーザ装置が開発されている。光ファイバレーザ装置は、光ファイバのコアに添加された希土類イオン等のレーザ媒質に対して、半導体レーザ等の励起光源から励起光を入光させることにより、レーザ光を発振又は増幅させる装置である。
　ここで、光ファイバに含まれるレーザ活性物質は励起光を吸収することによって発熱する。この発熱により、励起光からレーザ光への変換効率が変化するので、レーザ光の安定した出力を行うためには光ファイバの温度を一定にするのが望ましい。また、近年では、レーザ発振器の高出力化が進んでいるので、ファイバ内での発熱量が増大して損傷する場合がある。
　特に近年において、加工の高速化（生産性向上）のために、より高出力なファイバレーザが必要である。レーザは一般的に励起光源出力を向上することで、レーザ出力が増加する。しかし、励起光源出力の増加に伴う発熱も同時に増加する。例えば、Ｅｒ添加フッ化物ファイバの波長２．８μｍ帯域のレーザ発振では、波長変換量子効率は３０％程度であり、残りの７０％は発振に寄与しないエネルギーとして、最終的に熱となる。そして、フッ化物ファイバはおよそ摂氏３００度で軟化するので、レーザの高出力化に伴って熱的影響を無視できない。
　つまり、いかに光ファイバケーブルを冷却するかは、安定したレーザ特性、増幅特性等を発揮するための重要な課題である。
　そこで、光ファイバ装置は、一般に、冷却装置を有している（例えば、特許文献１を参照）。 A laser device using an optical fiber cable as a medium of laser light, a so-called optical fiber laser device, has been developed. An optical fiber laser device is a device that oscillates or amplifies laser light by inputting excitation light from an excitation light source such as a semiconductor laser to a laser medium such as a rare earth ion added to the core of an optical fiber. .
Here, the laser active substance contained in the optical fiber generates heat by absorbing the excitation light. Since the conversion efficiency from the excitation light to the laser light changes due to this heat generation, it is desirable to keep the temperature of the optical fiber constant in order to stably output the laser light. Further, in recent years, as the output of the laser oscillator has been increased, the amount of heat generated in the fiber may be increased and the fiber may be damaged.
Particularly in recent years, a higher output fiber laser is required for speeding up processing (improving productivity). Generally, the laser output is increased by improving the output of the excitation light source. However, heat generation accompanying an increase in the output of the excitation light source also increases at the same time. For example, in the laser oscillation of the Er-doped fluoride fiber in the wavelength band of 2.8 μm, the wavelength conversion quantum efficiency is about 30%, and the remaining 70% is finally heat as energy not contributing to oscillation. Since the fluoride fiber softens at about 300 degrees Celsius, the thermal effect cannot be ignored with the increase in the output of the laser.
In other words, how to cool the optical fiber cable is an important issue for exhibiting stable laser characteristics, amplification characteristics, and the like.
Therefore, the optical fiber device generally has a cooling device (for example, see Patent Document 1).
特開２０１２－２３２７４号公報JP 2012-23274 A
　特許文献１に記載の光ファイバ冷却装置では、光ファイバをヒートシンクに対して金属製の放熱部材を介して密着させている。この装置では、放熱部材として銅やアルミといった金属は熱伝導に優れるが、固体であるので冷却対象の形状に合せて加工が必要である。また、固体金属は、高い加工精度を求められるので、密着性が不十分となる恐れがある。
その場合は、効率よく光ファイバを冷却することができない。
　なお、樹脂やグリスは密着性が高いが熱伝導が低いので、冷却性に劣る。 In the optical fiber cooling device described in Patent Literature 1, the optical fiber is brought into close contact with a heat sink via a metal heat radiating member. In this apparatus, metals such as copper and aluminum are excellent in heat conduction as heat dissipating members, but since they are solid, they need to be processed according to the shape of the object to be cooled. In addition, since solid metal is required to have high processing accuracy, there is a possibility that the adhesion may be insufficient.
In that case, the optical fiber cannot be cooled efficiently.
Note that resin and grease have high adhesiveness but low thermal conductivity, and thus are inferior in cooling performance.
　本発明の目的は、光ファイバ冷却装置の冷却性能を向上させることにある。 An object of the present invention is to improve the cooling performance of an optical fiber cooling device.
　以下に、課題を解決するための手段として複数の態様を説明する。これら態様は、必要に応じて任意に組み合せることができる。 複数 Hereinafter, a plurality of embodiments will be described as means for solving the problems. These embodiments can be arbitrarily combined as needed.
　本発明の一見地に係る光ファイバ冷却装置は、収納部と、液状金属と、冷却装置とを備えている。
　収納部は、光ファイバの少なくとも一部を収納する。
　液状金属は、収納部内に配置されている。
　冷却装置は、液状金属を冷却する。
　この装置では、光ファイバを冷却する性能が向上する。液状金属が常温で液状であるので光ファイバとの密着性に優れ、熱伝導が良い（例えば、水の約２７．５倍）からである。したがって、光ファイバ冷却装置の冷却性能が向上する。 An optical fiber cooling device according to an aspect of the present invention includes a storage unit, a liquid metal, and a cooling device.
The storage section stores at least a part of the optical fiber.
The liquid metal is disposed in the storage section.
The cooling device cools the liquid metal.
In this device, the performance of cooling the optical fiber is improved. This is because the liquid metal is liquid at room temperature, so that it has excellent adhesion to the optical fiber and good heat conduction (for example, about 27.5 times water). Therefore, the cooling performance of the optical fiber cooling device is improved.
　光ファイバは、第１光ファイバと、第２光ファイバと、両者の接続部とを有していてもよい。
　接続部が収納部に収納されていてもよい。
　この装置では、光ファイバの冷却が効率的に行われる。接続部が最も発熱する部分だからである。 The optical fiber may include a first optical fiber, a second optical fiber, and a connection portion between both.
The connection part may be stored in the storage part.
In this device, the optical fiber is cooled efficiently. This is because the connection portion is the portion that generates the most heat.
　光ファイバ冷却装置は、液状金属を収納部から出して戻す循環装置をさらに備えていてもよい。
　冷却装置は、循環装置の一部において液状金属を冷却してもよい。
　この装置では、冷却装置の設置の自由度が高くなる。 The optical fiber cooling device may further include a circulation device for returning the liquid metal from the storage unit and returning the same.
The cooling device may cool the liquid metal in a part of the circulation device.
In this device, the degree of freedom of installation of the cooling device is increased.
　液状金属は、ガリウム、インジウム、水銀、スズ、鉛、銅、亜鉛及びビスマスからなる群から選択される１つ以上の金属を含んでいてもよい。
　この装置では、光ファイバを冷却する性能がさらに向上する。 The liquid metal may include one or more metals selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth.
In this device, the performance of cooling the optical fiber is further improved.
　液状金属は、ガリウム、インジウム、スズの合金からなっていてもよい。
　この装置では、光ファイバを冷却する性能がさらに向上する。
　本発明の他の見地に係る光ファイバレーザ装置は、光ファイバと、前記光ファイバ冷却装置とを備えている。 The liquid metal may comprise an alloy of gallium, indium and tin.
In this device, the performance of cooling the optical fiber is further improved.
An optical fiber laser device according to another aspect of the present invention includes an optical fiber and the optical fiber cooling device.
　本発明の他の見地に係る光ファイバ冷却装置は、光ファイバを冷却する装置であって、収納部と、液状金属と、冷却装置とを備えている。
　収納部は、光ファイバの少なくとも一部を収納する。
　液状金属は、収納部内に配置されている。
　冷却装置は、収納部を外側から冷却することで、液状金属を冷却する。
　この装置では、光ファイバを冷却する性能が向上する。液状金属が常温で液状であるのでファイバとの密着性に優れ、熱伝導が良い（例えば、水の約２７．５倍）からである。したがって、光ファイバ冷却装置の冷却性能が向上する。
　特に、筐体を直接冷却しているので、構造が簡素化し、液状金属の冷却効果が高くなる。 An optical fiber cooling device according to another aspect of the present invention is a device for cooling an optical fiber, and includes a storage unit, a liquid metal, and a cooling device.
The storage section stores at least a part of the optical fiber.
The liquid metal is disposed in the storage section.
The cooling device cools the liquid metal by cooling the storage unit from the outside.
In this device, the performance of cooling the optical fiber is improved. Because the liquid metal is liquid at room temperature, it has excellent adhesion to the fiber and good heat conduction (for example, about 27.5 times water). Therefore, the cooling performance of the optical fiber cooling device is improved.
In particular, since the housing is directly cooled, the structure is simplified, and the cooling effect of the liquid metal is enhanced.
　光ファイバは、第１光ファイバと、第２光ファイバと、両者の接続部とを有していてもよい。
　接続部が収納部に収納されていてもよい。
　この装置では、光ファイバの冷却が効率的に行われる。接続部が最も発熱する部分だからである。 The optical fiber may include a first optical fiber, a second optical fiber, and a connection portion between both.
The connection part may be stored in the storage part.
In this device, the optical fiber is cooled efficiently. This is because the connection portion is the portion that generates the most heat.
　収納部は、金属製本体と、脆化防止コートとを有していてもよい。金属製本体は、液状金属を収納する空間を構成する内壁面を有していてもよい。脆化防止コートは、内壁面に形成されていてもよい。脆化防止コートは液状金属に浸食されない材料とする。
　この装置では、収納部が金属製であるので、熱伝導が良い。そのため、液状金属を冷却する効果が高くなる。
　また、脆化防止コートによって、収納部の金属製本体が液状金属に対して保護される。したがって、金属製本体の脆化が防止される。 The storage section may include a metal body and an embrittlement prevention coat. The metal body may have an inner wall surface that forms a space for storing the liquid metal. The embrittlement prevention coat may be formed on the inner wall surface. The embrittlement prevention coat is made of a material that is not eroded by the liquid metal.
In this device, since the storage portion is made of metal, heat conduction is good. Therefore, the effect of cooling the liquid metal is enhanced.
Further, the metal body of the storage section is protected against the liquid metal by the embrittlement prevention coat. Therefore, embrittlement of the metal body is prevented.
　液状金属は、ガリウム、インジウム、水銀、スズ、鉛、銅、亜鉛及びビスマスからなる群から選択される１つ以上の金属を含んでいてもよい。
　この装置では、光ファイバを冷却する性能がさらに向上する。 The liquid metal may include one or more metals selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth.
In this device, the performance of cooling the optical fiber is further improved.
　液状金属は、ガリウム、インジウム、スズの合金からなっていてもよい。
　この装置では、光ファイバを冷却する性能がさらに向上する。
　本発明の他の見地に係る光ファイバレーザ装置は、光ファイバと、前記光ファイバ冷却装置とを備えている。 The liquid metal may comprise an alloy of gallium, indium and tin.
In this device, the performance of cooling the optical fiber is further improved.
An optical fiber laser device according to another aspect of the present invention includes an optical fiber and the optical fiber cooling device.
　本発明に係る光ファイバ冷却装置では、冷却性能が向上する。 冷却 In the optical fiber cooling device according to the present invention, the cooling performance is improved.
第１実施形態の光ファイバ及び光ファイバ冷却装置の模式的構成図。FIG. 1 is a schematic configuration diagram of an optical fiber and an optical fiber cooling device according to a first embodiment. 第１光ファイバ（非添加フッ化物ファイバ）の断面図。Sectional drawing of a 1st optical fiber (non-doped fluoride fiber). 第２光ファイバ（Ｅｒ添加フッ化物ファイバ）の断面図。Sectional drawing of the 2nd optical fiber (Er addition fluoride fiber). 光ファイバ冷却装置の制御構成を示すブロック図。FIG. 2 is a block diagram showing a control configuration of the optical fiber cooling device. 第２実施形態の光ファイバ及び光ファイバ冷却装置の模式的構成図。FIG. 5 is a schematic configuration diagram of an optical fiber and an optical fiber cooling device according to a second embodiment. 光ファイバ冷却装置の制御構成を示すブロック図。FIG. 2 is a block diagram showing a control configuration of the optical fiber cooling device.
１．第１実施形態
（１）レーザ発振器
　図１を用いて、レーザ発振器１の構成を説明する。図１は、光ファイバ及び光ファイバ冷却装置の模式的構成図である。 1. First Embodiment (1) Laser Oscillator The configuration of the laser oscillator 1 will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of an optical fiber and an optical fiber cooling device.
　レーザ発振器１は、一般的に、励起光源から励起光が入射されると、レーザ発振する。励起光源は、励起光を発振するものであり、例えば半導体レーザである。
　レーザ発振器の動作原理を説明する。レーザ発振器では、光ファイバの入力端から入射された励起光がコアを通過することで、コア内で励起光が吸収される。その後、誘導放出により、コア内部にて発光が増幅され、さらに光ファイバ内部を両端のミラーにより反射を繰り返すことにより、出力端からのレーザ発振に至る。 The laser oscillator 1 generally oscillates when excitation light is incident from an excitation light source. The excitation light source oscillates the excitation light, and is, for example, a semiconductor laser.
The operation principle of the laser oscillator will be described. In a laser oscillator, pumping light incident from an input end of an optical fiber passes through the core, so that the pumping light is absorbed in the core. Thereafter, light emission is amplified inside the core by stimulated emission, and furthermore, the inside of the optical fiber is repeatedly reflected by mirrors at both ends, thereby leading to laser oscillation from the output end.
　本実施形態では、レーザ発振器１は、励起光Ｌ１の入射によってレーザ光を発振するレーザ共振器３と、レーザ共振器３を冷却する光ファイバ冷却装置５とを有している。
　レーザ共振器３は、光ファイバ１５を有する。光ファイバ１５は、レーザ媒体及び共振器として機能し、励起光の照射により発生したレーザ光を増幅させてレーザ発振させる。 In the present embodiment, the laser oscillator 1 has a laser resonator 3 that oscillates a laser beam when the pump light L1 is incident, and an optical fiber cooling device 5 that cools the laser resonator 3.
The laser resonator 3 has an optical fiber 15. The optical fiber 15 functions as a laser medium and a resonator, amplifies laser light generated by irradiation with excitation light, and causes laser oscillation.
（２）光ファイバ
　光ファイバ１５は、第１光ファイバ１７と、第２光ファイバ１９とを有している。第１光ファイバ１７は、入力端１７ｄ及び出力端１７ｅを有している。入力端１７ｄには、第１エンドキャップ２５ａが接続されている。
　第２光ファイバ１９は、入力端１９ｄと出力端１９ｅとを有している。
　第１光ファイバ１７の出力端１７ｅと第２光ファイバ１９の入力端１９ｄが第１接続部２１によって融着接続されている。第２光ファイバ１９は、複数回巻かれた環状部１９ｆを形成している。
　第２光ファイバ１９の出力端１９ｅには、第１光ファイバ１７と同じ構成の第３光ファイバ２０が、第２接続部２２によって融着接続されている。 (2) Optical Fiber The optical fiber 15 has a first optical fiber 17 and a second optical fiber 19. The first optical fiber 17 has an input end 17d and an output end 17e. The first end cap 25a is connected to the input end 17d.
The second optical fiber 19 has an input end 19d and an output end 19e.
The output end 17 e of the first optical fiber 17 and the input end 19 d of the second optical fiber 19 are fusion-spliced by the first connection part 21. The second optical fiber 19 forms an annular portion 19f wound a plurality of times.
A third optical fiber 20 having the same configuration as that of the first optical fiber 17 is fusion-spliced to an output end 19 e of the second optical fiber 19 by a second connecting portion 22.
　第１光ファイバ１７は、図２に示すように、コア１７ａと、クラッド１７ｂと、バッファ１７ｃとを有する。図２は、第１光ファイバ（非添加フッ化物ファイバ）の断面図である。
　第１光ファイバ１７は、非添加フッ化物ファイバであり、励起光を伝播するために用いられる。
　コア１７ａは、例えばＺＢＬＡＮガラスであり、希土類は添加されていない。
　クラッド１７ｂは、コア１７ａの外周においてコア１７ａを覆うように形成されており、コア１７ａの屈折率よりも小さな屈折率を有する層である。
　バッファ１７ｃは、コア１７ａ及びクラッド１７ｂを外部刺激から保護するための層である。 The first optical fiber 17 has a core 17a, a clad 17b, and a buffer 17c, as shown in FIG. FIG. 2 is a cross-sectional view of the first optical fiber (non-doped fluoride fiber).
The first optical fiber 17 is a non-doped fluoride fiber, and is used to propagate the pump light.
The core 17a is made of, for example, ZBLAN glass, to which no rare earth is added.
The cladding 17b is formed so as to cover the core 17a on the outer periphery of the core 17a, and is a layer having a smaller refractive index than the core 17a.
The buffer 17c is a layer for protecting the core 17a and the clad 17b from external stimuli.
　第２光ファイバ１９は、希土類元素をドープしたフッ化物ファイバである。
　第２光ファイバ１９は、励起光により励起されることで、中赤外の波長（具体的には、２．８μｍ近辺）のレーザ光を出射する。第２光ファイバ１９は、入力端１９ｄから導入した励起光により励起され、第２光ファイバ１９にドープされた物質により決まる波長のレーザ光を発生する。 The second optical fiber 19 is a fluoride fiber doped with a rare earth element.
The second optical fiber 19 emits laser light of a mid-infrared wavelength (specifically, around 2.8 μm) by being excited by the excitation light. The second optical fiber 19 is excited by the excitation light introduced from the input end 19d, and generates a laser beam having a wavelength determined by the substance doped in the second optical fiber 19.
　第２光ファイバ１９は、図３に示すように、ダブルクラッドファイバであり、コア１９ａと、第１クラッド１９ｂと、第２クラッド１９ｃと、バッファ１９ｇとを有している。図３は、第２光ファイバ（Ｅｒ添加フッ化物ファイバ）の断面図である。
　コア１９ａは、希土類元素としてエルビウム（Ｅｒ）をドープしたＺＢＬＡＮガラスである。ＺＢＬＡＮガラスは、ジルコニウム（Ｚｒ）、バリウム（Ｂａ）、ランタン（Ｌａ）、アルミニウム（Ａｌ）、ナトリウム（Ｎａ）を主成分とするフッ化物ガラスである。なお、添加物質は、レーザ発振する物質であれば何でもよく、例えば、イッテルビウム（Ｙｂ）のような他の希土類元素でもよい。 As shown in FIG. 3, the second optical fiber 19 is a double clad fiber, and has a core 19a, a first clad 19b, a second clad 19c, and a buffer 19g. FIG. 3 is a cross-sectional view of the second optical fiber (Er-doped fluoride fiber).
The core 19a is a ZBLAN glass doped with erbium (Er) as a rare earth element. ZBLAN glass is a fluoride glass containing zirconium (Zr), barium (Ba), lanthanum (La), aluminum (Al), and sodium (Na) as main components. Note that the additive substance may be any substance as long as the substance oscillates laser, and may be, for example, another rare earth element such as ytterbium (Yb).
　第１クラッド１９ｂ及び第２クラッド１９ｃは、コア１９ａの外周においてコア１９ａを覆うように形成されており、コア１９ａの屈折率よりも小さな屈折率を有する層である。また、第１クラッド１９ｂ及び第２クラッド１９ｃには、希土類元素は添加されていない。
　バッファ１９ｇはコア１９ａ及び第１クラッド１９ｂと第２クラッド１９ｃを外部からの物理的圧力から保護するための層である。
　上記の構造により、第２光ファイバ１９は、主に励起光を波長２．８μｍ帯域の光に変換することができる。具体的には、第１クラッド１９ｂにおいて、主に波長２．８μｍ帯域の光を反射させて、コア１９ａを伝搬させる。また、第２クラッド１９ｃにおいて、主に励起光を反射させて、第１クラッド１９ｂとコア１９ａを伝搬させる。コア１９ａを励起光が通過すると、吸収が起こり、波長２．８μｍ帯域の光に変換される。
　第２光ファイバ１９の環状部１９ｆは、コア１９ａ内を伝播する光が第１クラッド１９ｂに漏れない最小半径よりも大きな半径で曲げられている。 The first cladding 19b and the second cladding 19c are formed so as to cover the core 19a on the outer periphery of the core 19a, and are layers having a smaller refractive index than the core 19a. Further, the first cladding 19b and the second cladding 19c do not contain a rare earth element.
The buffer 19g is a layer for protecting the core 19a, the first clad 19b, and the second clad 19c from external physical pressure.
With the above structure, the second optical fiber 19 can mainly convert the pump light into light having a wavelength band of 2.8 μm. Specifically, in the first cladding 19b, light mainly in the 2.8 μm wavelength band is reflected and propagated through the core 19a. Further, in the second cladding 19c, the excitation light is mainly reflected and propagates through the first cladding 19b and the core 19a. When the excitation light passes through the core 19a, absorption occurs, and the light is converted into light in a wavelength band of 2.8 μm.
The annular portion 19f of the second optical fiber 19 is bent at a radius larger than the minimum radius at which light propagating in the core 19a does not leak to the first clad 19b.
　第２光ファイバ１９には、図１に示すように、高反射ＦＢＧ（Ｆｉｂｅｒ　Ｂｒａｇｇ　Ｇｒａｔｉｎｇ）２３と、低反射ＦＢＧ２５とが描き込まれている。高反射ＦＢＧ２３は、第２光ファイバ１９の入力端１９ｄ近傍つまり第１接続部２１近傍に描き込まれている。低反射ＦＢＧ２５は、第２光ファイバ１９の出力端１９ｅに近い側に描き込まれている。
　高反射ＦＢＧ２３は、レーザ共振器３において、レーザ光として発振させる特定の波長を持つ光を全反射する反射部である。
　低反射ＦＢＧ２５は、レーザ共振器３において、レーザ光として発振させる特定の波長を持つ光のうち、一部のみを透過し、残りを反射する反射部である。 As shown in FIG. 1, a high-reflection FBG (Fiber Bragg Grating) 23 and a low-reflection FBG 25 are drawn in the second optical fiber 19. The high reflection FBG 23 is drawn near the input end 19 d of the second optical fiber 19, that is, near the first connection part 21. The low reflection FBG 25 is drawn on the side near the output end 19 e of the second optical fiber 19.
The high reflection FBG 23 is a reflection unit that totally reflects light having a specific wavelength to be oscillated as laser light in the laser resonator 3.
The low reflection FBG 25 is a reflection unit that transmits only a part of the light having a specific wavelength that is oscillated as laser light in the laser resonator 3 and reflects the rest.
　第１エンドキャップ２５ａは、励起光及びレーザ光を透過する光透過性であり、且つ潮解性を有さない。また、第１エンドキャップ２５ａは、融点が第１光ファイバ１７の融点以上とすることが好ましく、第１光ファイバ１７の端面の冷却のために熱伝導率は第１光ファイバ１７の熱伝導率よりも高いことが好ましい。また、第１エンドキャップ２５ａは、第１光ファイバ１７との接合を強固にするために、線膨張係数が第１光ファイバ１７と同程度のものが好ましい。具体的には、第１エンドキャップ２５ａは、フッ化カルシウムなどの結晶とすることができる。第１エンドキャップ２５ａは、他にも石英などの結晶であってもよい。
　なお、第２エンドキャップ２５ｂは、第１エンドキャップ２５ａと同じ構成である。
　第３光ファイバ２０は、レーザ光が内部で反射する前に出射される長さを有している。また、第３光ファイバ２０は、レーザ媒質であるエルビウムなどの希土類元素がドープされていないため、励起光が入射されても発熱しない。 The first end cap 25a is light transmissive for transmitting the excitation light and the laser light, and has no deliquescence. Further, the first end cap 25a preferably has a melting point equal to or higher than the melting point of the first optical fiber 17, and the thermal conductivity of the first optical fiber 17 for cooling the end face thereof is lower than that of the first optical fiber 17. It is preferably higher than that. The first end cap 25a preferably has a linear expansion coefficient substantially equal to that of the first optical fiber 17 in order to strengthen the bonding with the first optical fiber 17. Specifically, the first end cap 25a can be a crystal such as calcium fluoride. The first end cap 25a may be made of other crystal such as quartz.
The second end cap 25b has the same configuration as the first end cap 25a.
The third optical fiber 20 has a length that is emitted before the laser light is reflected inside. Further, since the third optical fiber 20 is not doped with a rare earth element such as erbium which is a laser medium, it does not generate heat even when excitation light is incident.
　以上の光ファイバ１５の構成により、レーザ共振器３が形成されている。レーザ共振器３では、第２光ファイバ１９のコア１９ａにドープされた希土類元素に吸収されて、基底準位と準安定準位との間に反転分布が生じて光が放出される。こうして放出された光は、第２光ファイバ１９の光増幅作用と高反射ＦＢＧ２３及び低反射ＦＢＧ２５の作用とによって、レーザ発振する。出力光は、第２光ファイバ１９の出力端１９ｅから出力される。
　出力光は、ダイクロイックミラー２７へ誘導される。ダイクロイックミラー２７は、励起光源からの励起光Ｌ２は透過するが、レーザ光Ｌ３は透過することなく反射する。ダイクロイックミラー２７で反射したレーザ光Ｌ３を出力として、種々の目的に使用される。
　ダンパ２９（例えば、光出力を測る機能を有する装置）は、ダイクロイックミラー２７の下流側に配置されており、ダイクロイックミラー２７が透過した励起光Ｌ２を吸収し測定できる。これにより出力を制御装置（例えば、制御部５１）で監視できる。 The laser resonator 3 is formed by the configuration of the optical fiber 15 described above. In the laser resonator 3, the light is emitted by being absorbed by the rare earth element doped in the core 19a of the second optical fiber 19, causing a population inversion between the ground level and the metastable level. The light thus emitted oscillates by the light amplifying action of the second optical fiber 19 and the action of the high reflection FBG 23 and the low reflection FBG 25. The output light is output from an output end 19e of the second optical fiber 19.
The output light is guided to the dichroic mirror 27. The dichroic mirror 27 transmits the excitation light L2 from the excitation light source, but reflects the laser light L3 without transmitting. The laser beam L3 reflected by the dichroic mirror 27 is used as an output for various purposes.
The damper 29 (for example, a device having a function of measuring light output) is disposed downstream of the dichroic mirror 27, and can absorb and measure the excitation light L2 transmitted by the dichroic mirror 27. Thus, the output can be monitored by the control device (for example, the control unit 51).
（３）光ファイバ冷却装置
　光ファイバ冷却装置５は、冷却された液状金属Ｍを用いて光ファイバ１５を冷却する装置である。光ファイバ冷却装置５は、筐体３３（収納部の一例）と、循環装置３５と、チラー装置３７（冷却装置の一例）と、を有している。
　筐体３３は、箱状に形成されており、第２光ファイバ１９を保持するとともに、第２光ファイバ１９を直接に冷却するための装置である。筐体３３は、第２光ファイバ１９の環状部１９ｆを収容する内部空間３３ａを有している。この構造により、筐体３３によって第２光ファイバ１９は保持される。筐体３３は、例えば、アクリル製である。
　さらに、内部空間３３ａには、液状金属Ｍが充填されている。内部空間３３ａには、液状金属Ｍが循環可能な環状の通路が形成されている。 (3) Optical Fiber Cooling Device The optical fiber cooling device 5 is a device that cools the optical fiber 15 using the cooled liquid metal M. The optical fiber cooling device 5 includes a housing 33 (an example of a storage unit), a circulation device 35, and a chiller device 37 (an example of a cooling device).
The housing 33 is a device that is formed in a box shape, holds the second optical fiber 19, and directly cools the second optical fiber 19. The housing 33 has an internal space 33a for accommodating the annular portion 19f of the second optical fiber 19. With this structure, the housing 33 holds the second optical fiber 19. The housing 33 is made of, for example, acrylic.
Further, the internal space 33a is filled with the liquid metal M. An annular passage through which the liquid metal M can circulate is formed in the internal space 33a.
　循環装置３５は、液状金属Ｍを筐体３３から出して戻す装置である。循環装置３５は、配管４３とポンプ４５とを有している。配管４３は、筐体３３の内部空間３３ａに設けられた流入ポート３３ｂと流出ポート３３ｃに接続されている。
　チラー装置３７は、循環装置３５の一部において、筐体３３の内部空間３３ａを流れる液状金属Ｍを冷却する。チラー装置３７は、配管４３において、例えば二重管構造によって水を用いて液状金属Ｍを冷却する。
　液状金属Ｍは、筐体３３の内部空間３３ａからポンプ４５によって配管４３を介して、チラー装置３７に送られる。液状金属Ｍはチラー装置３７によって冷却される。その後、液状金属Ｍは配管４３を介して筐体３３に戻される。 The circulation device 35 is a device that returns the liquid metal M from the housing 33 and returns it. The circulation device 35 has a pipe 43 and a pump 45. The pipe 43 is connected to an inflow port 33b and an outflow port 33c provided in the internal space 33a of the housing 33.
The chiller device 37 cools the liquid metal M flowing through the internal space 33 a of the housing 33 in a part of the circulation device 35. The chiller device 37 cools the liquid metal M in the pipe 43 by using water, for example, by a double pipe structure.
The liquid metal M is sent from the internal space 33 a of the housing 33 to the chiller device 37 via the pipe 43 by the pump 45. The liquid metal M is cooled by the chiller device 37. Thereafter, the liquid metal M is returned to the housing 33 via the pipe 43.
　液状金属Ｍは、ガリウム、インジウム、水銀、スズ、鉛、銅、亜鉛及びビスマスからなる群から選択される１つ以上の金属を含んでいる。具体的には、液状金属Ｍは、ガリウム、インジウム、スズの合金からなる。ガリウム、インジウム、スズの合金は、熱伝導率が約１６．５［Ｗ／ｍＫ］である。
　この装置では、液状金属Ｍが常温で液状であるので第２光ファイバ１９との密着性に優れ、熱伝導性が良い（例えば、水の約２７．５倍）。したがって、冷却性能が向上する。 The liquid metal M includes one or more metals selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth. Specifically, the liquid metal M is made of an alloy of gallium, indium, and tin. The alloy of gallium, indium, and tin has a thermal conductivity of about 16.5 [W / mK].
In this device, since the liquid metal M is liquid at room temperature, it has excellent adhesion to the second optical fiber 19 and good thermal conductivity (for example, about 27.5 times water). Therefore, the cooling performance is improved.
　内部空間３３ａに液状金属Ｍの流れＦが生じることから、熱量を吸収した液状金属Ｍが内部空間３３ａに滞留することがなく、熱量の吸収効率をより高めることができる。
　ガリウム、インジウム、スズの合金は、例えば、Ｇａ１４Ｉｎ３Ｓｎ２、Ｇａ１７Ｉｎ４Ｓｎ２、Ｇａ２２Ｉｎ４Ｓｎ３、Ｇａ２５Ｉｎ５Ｓｎ４、Ｇａ２５Ｉｎ６Ｓｎ３を含む。
　特に、第１接続部２１と、第２光ファイバ１９の入力端１９ｄが液状金属Ｍに接して冷却されていることで、発熱防止効果が優れている。 Since the flow F of the liquid metal M is generated in the internal space 33a, the liquid metal M that has absorbed the heat amount does not stay in the internal space 33a, and the heat absorption efficiency can be further improved.
Gallium, indium, tin alloy, for example, a Ga 14 In 3 Sn 2, Ga 17 In 4 Sn 2, Ga 22 In 4 Sn 3, Ga 25 In 5 Sn 4, Ga 25 In 6 Sn 3.
In particular, since the first connection portion 21 and the input end 19d of the second optical fiber 19 are cooled while being in contact with the liquid metal M, the effect of preventing heat generation is excellent.
（４）制御構成
　図４を用いて、光ファイバ冷却装置５の制御構成を説明する。図４は、光ファイバ冷却装置の制御構成を示すブロック図である。
　光ファイバ冷却装置５は、制御部５１を有している。制御部５１は、プロセッサ（例えば、ＣＰＵ）と、記憶装置（例えば、ＲＯＭ、ＲＡＭ、ＨＤＤ、ＳＳＤなど）と、各種インターフェース（例えば、Ａ／Ｄコンバータ、Ｄ／Ａコンバータ、通信インターフェースなど）を有するコンピュータシステムである。制御部５１は、記憶部（記憶装置の記憶領域の一部又は全部に対応）に保存されたプログラムを実行することで、各種制御動作を行う。
　制御部５１は、単一のプロセッサで構成されていてもよいが、各制御のために独立した複数のプロセッサから構成されていてもよい。 (4) Control Configuration The control configuration of the optical fiber cooling device 5 will be described with reference to FIG. FIG. 4 is a block diagram showing a control configuration of the optical fiber cooling device.
The optical fiber cooling device 5 has a control unit 51. The control unit 51 has a processor (for example, CPU), a storage device (for example, ROM, RAM, HDD, SSD, etc.) and various interfaces (for example, A / D converter, D / A converter, communication interface, etc.). It is a computer system. The control unit 51 performs various control operations by executing a program stored in a storage unit (corresponding to part or all of the storage area of the storage device).
The control unit 51 may be configured by a single processor, or may be configured by a plurality of independent processors for each control.
　制御部５１の各要素の機能は、一部又は全てが、制御部５１を構成するコンピュータシステムにて実行可能なプログラムとして実現されてもよい。その他、制御部５１の各要素の機能の一部は、カスタムＩＣにより構成されていてもよい。
　制御部５１には、循環装置３５のポンプ４５、チラー装置３７が接続されている。制御部５１は、これら及び他の装置を制御可能である。
　制御部５１には、図示しないが、各装置の状態を検出するためのセンサ及びスイッチ、並びに情報入力装置が接続されている。 A part or all of the functions of each element of the control unit 51 may be realized as a program that can be executed by a computer system configuring the control unit 51. In addition, a part of the function of each element of the control unit 51 may be configured by a custom IC.
The pump 45 of the circulation device 35 and the chiller device 37 are connected to the control unit 51. The control unit 51 can control these and other devices.
Although not shown, sensors and switches for detecting the state of each device and an information input device are connected to the control unit 51.
（５）動作
　最初に、励起光源（図示せず）において、励起光が発振される。励起光は、光ファイバ１５に具体的には第１エンドキャップ２５ａを通って第１光ファイバ１７の入力端１７ｄに入射する。
　励起光は第１光ファイバ１７から第２光ファイバ１９へと送られる。励起光は、高反射ＦＢＧ２３を通って第２光ファイバ１９に入射する。この後、励起光によってコア１９ａの活性物質が励起され、活性物質から光が放出される。この後、活性物質から放出された光は、コア１９ａ内を伝搬されながら高反射ＦＢＧ２３と低反射ＦＢＧ２５との間で往復する。この結果、特定の波長を持つ光がレーザ光として第２光ファイバ１９から低反射ＦＢＧ２５を透過して外部へ出射される。具体的には、レーザ光は、第３光ファイバ２０及び第２エンドキャップ２５ｂを通って外部に出射される。 (5) Operation First, an excitation light source (not shown) emits excitation light. The pump light enters the optical fiber 15, specifically, the input end 17 d of the first optical fiber 17 through the first end cap 25 a.
The pump light is sent from the first optical fiber 17 to the second optical fiber 19. The excitation light enters the second optical fiber 19 through the high reflection FBG 23. Thereafter, the active substance in the core 19a is excited by the excitation light, and light is emitted from the active substance. Thereafter, the light emitted from the active substance reciprocates between the high-reflection FBG 23 and the low-reflection FBG 25 while propagating in the core 19a. As a result, light having a specific wavelength is emitted as laser light from the second optical fiber 19 through the low-reflection FBG 25 to the outside. Specifically, the laser light is emitted outside through the third optical fiber 20 and the second end cap 25b.
　そして、励起光Ｌ２は、ダイクロイックミラー２７を透過し、ダンパ２９（例えば、光出力を測る機能を有する装置）に吸収され測定される。それに基づいて、制御装置（例えば、制御部５１）が出力を監視できる。一方、第２光ファイバ１９のコア１９ａ内で生成されたレーザ光Ｌ３は、ダイクロイックミラー２７で反射されて、外部に出力される。
　以上のレーザ発振動作において、光ファイバ１５は発熱するが、光ファイバ１５は、光ファイバ冷却装置５によって効率よく冷却される。
　これにより、光ファイバ１５を効率良くかつより均一に冷却することができ、それにより冷却効率の向上できる。従って、レーザ発振器１では、レーザ光の出力の低下の防止を図ることができ、レーザ光の安定した出力を得ることができる。 Then, the excitation light L2 passes through the dichroic mirror 27, and is absorbed and measured by the damper 29 (for example, a device having a function of measuring an optical output). Based on this, the control device (for example, the control unit 51) can monitor the output. On the other hand, the laser light L3 generated in the core 19a of the second optical fiber 19 is reflected by the dichroic mirror 27 and output to the outside.
In the above laser oscillation operation, the optical fiber 15 generates heat, but the optical fiber 15 is efficiently cooled by the optical fiber cooling device 5.
Thereby, the optical fiber 15 can be cooled efficiently and more uniformly, and thereby the cooling efficiency can be improved. Therefore, in the laser oscillator 1, it is possible to prevent a decrease in the output of the laser light, and it is possible to obtain a stable output of the laser light.
２．第２実施形態
（１）レーザ発振器
　図５を用いて、レーザ発振器１０１の構成を説明する。図５は、第２実施形態の光ファイバ及び光ファイバ冷却装置の模式的構成図である。
　なお、第1実施形態と共通する構造については、適宜省略する。 2. Second Embodiment (1) Laser Oscillator The configuration of the laser oscillator 101 will be described with reference to FIG. FIG. 5 is a schematic configuration diagram of the optical fiber and the optical fiber cooling device according to the second embodiment.
Note that the structure common to the first embodiment is appropriately omitted.
　レーザ発振器１０１は、一般的に、励起光源から励起光が入射されると、レーザ発振する。励起光源は、励起光を発振するものであり、例えば半導体レーザである。 (4) The laser oscillator 101 generally oscillates laser when excitation light is incident from an excitation light source. The excitation light source oscillates the excitation light, and is, for example, a semiconductor laser.
　本実施形態では、レーザ発振器１０１は、励起光Ｌ１の入射によってレーザ光を発振するレーザ共振器３と、レーザ共振器３を冷却する光ファイバ冷却装置１０５とを有している。
　レーザ共振器３は、光ファイバ１５を有する。光ファイバ１５は、レーザ媒体及び共振器として機能し、励起光の照射により発生したレーザ光を増幅させてレーザ発振させる。 In the present embodiment, the laser oscillator 101 includes the laser resonator 3 that oscillates a laser beam when the pump light L1 is incident, and the optical fiber cooling device 105 that cools the laser resonator 3.
The laser resonator 3 has an optical fiber 15. The optical fiber 15 functions as a laser medium and a resonator, amplifies laser light generated by irradiation with excitation light, and causes laser oscillation.
（２）光ファイバ
　光ファイバ１５は、第１実施形態のものと同じである。したがって、ここでは説明を省略する。 (2) Optical Fiber The optical fiber 15 is the same as that of the first embodiment. Therefore, the description is omitted here.
（３）光ファイバ冷却装置
　光ファイバ冷却装置１０５は、冷却された液状金属Ｍを用いて光ファイバ１５を冷却する装置である。光ファイバ冷却装置１０５は、筐体１３３（収納部の一例）と、チラー装置１３７（冷却装置の一例）と、を有している。
　筐体１３３は、箱状に形成されており、第２光ファイバ１９を保持するとともに、第２光ファイバ１９を直接に冷却するための装置である。筐体１３３は、第２光ファイバ１９の環状部１９ｆを収容する内部空間１３３ａを有している。この構造により、筐体１３３によって第２光ファイバ１９は保持される。 (3) Optical Fiber Cooling Device The optical fiber cooling device 105 is a device that cools the optical fiber 15 using the cooled liquid metal M. The optical fiber cooling device 105 includes a housing 133 (an example of a storage unit) and a chiller device 137 (an example of a cooling device).
The casing 133 is a box-shaped device that holds the second optical fiber 19 and directly cools the second optical fiber 19. The housing 133 has an internal space 133a that accommodates the annular portion 19f of the second optical fiber 19. With this structure, the second optical fiber 19 is held by the housing 133.
　さらに、内部空間１３３ａには、液状金属Ｍが充填されている。内部空間１３３ａには、液状金属Ｍが循環可能な環状の通路が形成されている。
　チラー装置１３７は、筐体１３３の外部から、筐体１３３の内部空間１３３ａに滞留する液状金属Ｍを冷却する。
　この装置では、光ファイバ１５を冷却する性能が向上する。液状金属が常温で液状であるので光ファイバ１５との密着性に優れ、熱伝導が良い（例えば、水の約２７．５倍）からである。したがって、光ファイバ冷却装置１０５の冷却性能が向上する。
　特に、筐体１３３を直接冷却しているので、構造が簡素化し、液状金属Ｍの冷却効果が高くなる。 Further, the internal space 133a is filled with the liquid metal M. An annular passage through which the liquid metal M can circulate is formed in the internal space 133a.
The chiller device 137 cools the liquid metal M staying in the internal space 133a of the housing 133 from outside the housing 133.
In this device, the performance of cooling the optical fiber 15 is improved. This is because the liquid metal is liquid at room temperature, so that it has excellent adhesion to the optical fiber 15 and good heat conduction (for example, about 27.5 times water). Therefore, the cooling performance of the optical fiber cooling device 105 is improved.
In particular, since the housing 133 is directly cooled, the structure is simplified, and the cooling effect of the liquid metal M is enhanced.
　チラー装置１３７は、筐体１３３の少なくとも一側面に接触している。チラー装置１３７は、筐体１３３の複数の側面に接触していてもよいし、筐体１３３の一部又は全部を覆った状態で筐体１３３に接触していてもよい。 The chiller device 137 is in contact with at least one side surface of the housing 133. The chiller device 137 may be in contact with a plurality of side surfaces of the housing 133, or may be in contact with the housing 133 while partially or entirely covering the housing 133.
　筐体１３３は、金属製であり、内部空間１３３ａを構成する内壁面には脆化防止コートが形成されている。この場合、筐体１３３が金属製であるので、熱伝導が良い。そのため、液状金属Ｍを冷却する効果が高くなる。脆化防止コートは、例えば、熱やUV光で硬化する樹脂であり、具体的には、アクリル樹脂、エポキシ樹脂、テフロン（登録商標）樹脂である。
　また、脆化防止コートによって、収納部の金属製本体が液状金属Ｍに対して保護される。したがって、金属製本体の脆化が防止される。 The housing 133 is made of metal, and an embrittlement prevention coat is formed on an inner wall surface of the inner space 133a. In this case, since the housing 133 is made of metal, heat conduction is good. Therefore, the effect of cooling the liquid metal M increases. The embrittlement prevention coat is, for example, a resin that is cured by heat or UV light, and specifically, is an acrylic resin, an epoxy resin, or a Teflon (registered trademark) resin.
Further, the metal body of the storage section is protected against the liquid metal M by the embrittlement prevention coat. Therefore, embrittlement of the metal body is prevented.
　液状金属Ｍは、ガリウム、インジウム、水銀、スズ、鉛、銅、亜鉛及びビスマスからなる群から選択される１つ以上の金属を含んでいる。具体的には、液状金属Ｍは、ガリウム、インジウム、スズの合金からなる。ガリウム、インジウム、スズの合金は、熱伝導率が約１６．５［Ｗ／ｍＫ］である。
　この装置では、液状金属Ｍが常温で液状であるので第２光ファイバ１９との密着性に優れ、熱伝導性が良い（例えば、水の約２７．５倍）。したがって、冷却性能が向上する。 The liquid metal M includes one or more metals selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth. Specifically, the liquid metal M is made of an alloy of gallium, indium, and tin. The alloy of gallium, indium, and tin has a thermal conductivity of about 16.5 [W / mK].
In this device, since the liquid metal M is liquid at room temperature, it has excellent adhesion to the second optical fiber 19 and good thermal conductivity (for example, about 27.5 times water). Therefore, the cooling performance is improved.
　ガリウム、インジウム、スズの合金は、例えば、Ｇａ１４Ｉｎ３Ｓｎ２、Ｇａ１７Ｉｎ４Ｓｎ２、Ｇａ２２Ｉｎ４Ｓｎ３、Ｇａ２５Ｉｎ５Ｓｎ４、Ｇａ２５Ｉｎ６Ｓｎ３を含む。
　特に、第１接続部２１と、第２光ファイバ１９の入力端１９ｄが液状金属Ｍに接して冷却されていることで、発熱防止効果が高くなっている。 Gallium, indium, tin alloy, for example, a Ga 14 In 3 Sn 2, Ga 17 In 4 Sn 2, Ga 22 In 4 Sn 3, Ga 25 In 5 Sn 4, Ga 25 In 6 Sn 3.
In particular, since the first connection portion 21 and the input end 19d of the second optical fiber 19 are cooled while being in contact with the liquid metal M, the effect of preventing heat generation is enhanced.
（４）制御構成
　図６を用いて、光ファイバ冷却装置１０５の制御構成を説明する。図６は、光ファイバ冷却装置の制御構成を示すブロック図である。
　光ファイバ冷却装置１０５は、制御部５１を有している。制御部５１は、プロセッサ（例えば、ＣＰＵ）と、記憶装置（例えば、ＲＯＭ、ＲＡＭ、ＨＤＤ、ＳＳＤなど）と、各種インターフェース（例えば、Ａ／Ｄコンバータ、Ｄ／Ａコンバータ、通信インターフェースなど）を有するコンピュータシステムである。制御部５１は、記憶部（記憶装置の記憶領域の一部又は全部に対応）に保存されたプログラムを実行することで、各種制御動作を行う。
　制御部５１は、単一のプロセッサで構成されていてもよいが、各制御のために独立した複数のプロセッサから構成されていてもよい。 (4) Control Configuration The control configuration of the optical fiber cooling device 105 will be described with reference to FIG. FIG. 6 is a block diagram showing a control configuration of the optical fiber cooling device.
The optical fiber cooling device 105 has a control unit 51. The control unit 51 has a processor (for example, CPU), a storage device (for example, ROM, RAM, HDD, SSD, etc.) and various interfaces (for example, A / D converter, D / A converter, communication interface, etc.). It is a computer system. The control unit 51 performs various control operations by executing a program stored in a storage unit (corresponding to part or all of the storage area of the storage device).
The control unit 51 may be configured by a single processor, or may be configured by a plurality of independent processors for each control.
　制御部５１の各要素の機能は、一部又は全てが、制御部５１を構成するコンピュータシステムにて実行可能なプログラムとして実現されてもよい。その他、制御部５１の各要素の機能の一部は、カスタムＩＣにより構成されていてもよい。
　制御部５１には、チラー装置１３７が接続されている。制御部５１は、これら及び他の装置を制御可能である。
　制御部５１には、図示しないが、各装置の状態を検出するためのセンサ及びスイッチ、並びに情報入力装置が接続されている。 A part or all of the functions of each element of the control unit 51 may be realized as a program that can be executed by a computer system configuring the control unit 51. In addition, a part of the function of each element of the control unit 51 may be configured by a custom IC.
The chiller device 137 is connected to the control unit 51. The control unit 51 can control these and other devices.
Although not shown, sensors and switches for detecting the state of each device and an information input device are connected to the control unit 51.
（５）動作
　レーザ発振動作は、第１実施形態と同じである。従って、ここでは説明を省略する。
　レーザ発振動作において、光ファイバ１５は発熱するが、光ファイバ１５は、光ファイバ冷却装置１０５によって効率よく冷却される。
　これにより、光ファイバ１５を効率良くかつより均一に冷却することができ、それにより冷却効率の向上できる。従って、レーザ発振器１０１では、レーザ光の出力の低下の防止を図ることができ、レーザ光の安定した出力を得ることができる。 (5) Operation The laser oscillation operation is the same as in the first embodiment. Therefore, the description is omitted here.
In the laser oscillation operation, the optical fiber 15 generates heat, but the optical fiber 15 is efficiently cooled by the optical fiber cooling device 105.
Thereby, the optical fiber 15 can be cooled efficiently and more uniformly, and thereby the cooling efficiency can be improved. Therefore, in the laser oscillator 101, it is possible to prevent a decrease in the output of the laser light, and it is possible to obtain a stable output of the laser light.
３．他の実施形態
　以上、本発明の複数の実施形態について説明したが、本発明は上記実施形態に限定されるものではなく、発明の要旨を逸脱しない範囲で種々の変更が可能である。特に、本明細書に書かれた複数の実施形態及び変形例は必要に応じて任意に組み合せ可能である。
（１）第１実施形態及び第２実施形態では、第２光ファイバ１９を複数回巻いて環状にしているが、これに限定されず、第２光ファイバ１９の曲げ半径の条件を満たす範囲であれば、どのような形状に曲げていてもよい。 3. Other Embodiments A plurality of embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the invention. In particular, a plurality of embodiments and modifications described in this specification can be arbitrarily combined as needed.
(1) In the first embodiment and the second embodiment, the second optical fiber 19 is wound plural times to form an annular shape. However, the present invention is not limited to this. If so, it may be bent into any shape.
（２）光ファイバの用途は、レーザ発振に限定されない。
（３）光ファイバの内部構成及び長手方向構成は、前記実施形態に限定されない。
（４）第２実施形態において、流体金属及び光ファイバを収納する収納部の形状、材質は特に限定されない。 (2) The application of the optical fiber is not limited to laser oscillation.
(3) The internal configuration and the longitudinal configuration of the optical fiber are not limited to those in the above-described embodiment.
(4) In the second embodiment, the shape and material of the storage section that stores the fluid metal and the optical fiber are not particularly limited.
　本発明は、光ファイバ冷却装置に広く適用できる。 The present invention is widely applicable to optical fiber cooling devices.
１　　　　　　：レーザ発振器
３　　　　　　：レーザ共振器
５　　　　　　：光ファイバ冷却装置
１５　　　　　：光ファイバ
１７　　　　　：第１光ファイバ
１７ａ　　　　：コア
１７ｂ　　　　：クラッド
１７ｃ　　　　：バッファ
１９　　　　　：第２光ファイバ
１９ａ　　　　：コア
１９ｂ　　　　：第１クラッド
１９ｃ　　　　：第２クラッド
１９ｄ　　　　：バッファ
２１　　　　　：第１接続部
２３　　　　　：高反射ＦＢＧ
２５　　　　　：低反射ＦＢＧ
３３　　　　　：筐体
３３ａ　　　　：内部空間
３５　　　　　：循環装置
３７　　　　　：チラー装置
４３　　　　　：配管
４５　　　　　：ポンプ
５１　　　　　：制御部
６１　　　　　：冷却用管
６１ａ　　　　：流路
Ｍ　　　　　　：液状金属 1: laser oscillator 3: laser resonator 5: optical fiber cooling device 15: optical fiber 17: first optical fiber 17a: core 17b: clad 17c: buffer 19: second optical fiber 19a: core 19b: first clad 19c: Second clad 19d: buffer 21: first connection part 23: high reflection FBG
25: Low reflection FBG
33: housing 33a: internal space 35: circulation device 37: chiller device 43: piping 45: pump 51: control unit 61: cooling pipe 61a: flow path M: liquid metal

Claims (12)

  1. 　光ファイバの少なくとも一部を収納する収納部と、
    　前記収納部内に配置された液状金属と、
    　前記液状金属を冷却する冷却装置と、
    を備えた、光ファイバ冷却装置。     A storage unit that stores at least a part of the optical fiber,
    A liquid metal disposed in the storage portion,
    A cooling device for cooling the liquid metal,
    An optical fiber cooling device comprising:
  2. 　前記光ファイバは、第１光ファイバと、第２光ファイバと、両者の接続部とを有しており、
    　前記接続部が前記収納部に収納されている、請求項１に記載の光ファイバ冷却装置。     The optical fiber has a first optical fiber, a second optical fiber, and a connection portion between the two,
    The optical fiber cooling device according to claim 1, wherein the connection portion is stored in the storage portion.
  3. 　前記液状金属を前記収納部から出して戻す循環装置をさらに備え、
    　前記冷却装置は、前記循環装置の一部において前記液状金属を冷却する、請求項１又は２に記載の光ファイバ冷却装置。     A circulation device for returning the liquid metal out of the storage section,
    The optical fiber cooling device according to claim 1, wherein the cooling device cools the liquid metal in a part of the circulation device.
  4. 　前記液状金属は、ガリウム、インジウム、水銀、スズ、鉛、銅、亜鉛及びビスマスからなる群から選択される１つ以上の金属を含む、請求項１～３のいずれかに記載の光ファイバ冷却装置。 4. The optical fiber cooling device according to claim 1, wherein the liquid metal includes at least one metal selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth. .
  5. 　前記液状金属は、ガリウム、インジウム、スズの合金からなる、請求項４に記載の光ファイバ冷却装置。 The optical fiber cooling device according to claim 4, wherein the liquid metal comprises an alloy of gallium, indium, and tin.
  6. 　光ファイバと、
    　前記光ファイバを冷却するための光ファイバ冷却装置とを、備え、
    　前記光ファイバ冷却装置は、
    　光ファイバの少なくとも一部を収納する収納部と、
    　前記収納部内に配置された液状金属と、
    　前記液状金属を冷却する冷却装置と、を有する、
    光ファイバレーザ装置。     Optical fiber,
    An optical fiber cooling device for cooling the optical fiber,
    The optical fiber cooling device,
    A storage unit that stores at least a part of the optical fiber,
    A liquid metal disposed in the storage portion,
    And a cooling device for cooling the liquid metal,
    Optical fiber laser device.
  7. 　光ファイバを冷却する装置であって、
    　前記光ファイバの少なくとも一部を収納する収納部と、
    　前記収納部内に配置された液状金属と、
    　前記収納部を外側から冷却することで、前記液状金属を冷却する冷却装置と、
    を備えた、光ファイバ冷却装置。     An apparatus for cooling an optical fiber,
    A storage unit that stores at least a part of the optical fiber,
    A liquid metal disposed in the storage portion,
    By cooling the storage unit from the outside, a cooling device that cools the liquid metal,
    An optical fiber cooling device comprising:
  8. 　前記光ファイバは、第１光ファイバと、第２光ファイバと、両者の接続部とを有しており、
    　前記接続部が前記収納部に収納されている、請求項７に記載の光ファイバ冷却装置。     The optical fiber has a first optical fiber, a second optical fiber, and a connection portion between the two,
    The optical fiber cooling device according to claim 7, wherein the connection portion is stored in the storage portion.
  9. 　前記収納部は、
    　前記液状金属を収納する空間を構成する内壁面を有する金属製本体と、
    　前記内壁面に形成された脆化防止コートと、を有する、請求項７又は８に記載の光ファイバ冷却装置。     The storage section,
    A metal body having an inner wall surface that constitutes a space for containing the liquid metal,
    The optical fiber cooling device according to claim 7, further comprising: an embrittlement prevention coat formed on the inner wall surface.
  10. 　前記液状金属は、ガリウム、インジウム、水銀、スズ、鉛、銅、亜鉛及びビスマスからなる群から選択される１つ以上の金属を含む、請求項７～９のいずれかに記載の光ファイバ冷却装置。 The optical fiber cooling device according to any one of claims 7 to 9, wherein the liquid metal includes one or more metals selected from the group consisting of gallium, indium, mercury, tin, lead, copper, zinc, and bismuth. .
  11. 　前記液状金属は、ガリウム、インジウム、スズの合金からなる、請求項１０に記載の光ファイバ冷却装置。 The optical fiber cooling device according to claim 10, wherein the liquid metal comprises an alloy of gallium, indium, and tin.
  12. 　光ファイバと、
    　前記光ファイバを冷却する光ファイバ冷却装置と、を備え、
    　前記光ファイバ冷却装置は、
    　前記光ファイバの少なくとも一部を収納する収納部と、
    　前記収納部内に配置された液状金属と、
    　前記収納部を外側から冷却することで、前記液状金属を冷却する冷却装置と、を有する、光ファイバレーザ装置。     Optical fiber,
    An optical fiber cooling device that cools the optical fiber,
    The optical fiber cooling device,
    A storage unit that stores at least a part of the optical fiber,
    A liquid metal disposed in the storage portion,
    A cooling device that cools the liquid metal by cooling the storage section from outside.
PCT/JP2019/033296 2018-09-21 2019-08-26 Optical fiber cooling device and optical fiber laser device WO2020059433A1 (en)

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