[go: up one dir, main page]

WO2019189317A1 - Dispositif photodétecteur et système laser - Google Patents

Dispositif photodétecteur et système laser Download PDF

Info

Publication number
WO2019189317A1
WO2019189317A1 PCT/JP2019/013105 JP2019013105W WO2019189317A1 WO 2019189317 A1 WO2019189317 A1 WO 2019189317A1 JP 2019013105 W JP2019013105 W JP 2019013105W WO 2019189317 A1 WO2019189317 A1 WO 2019189317A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
optical fiber
refractive index
resin
region
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2019/013105
Other languages
English (en)
Japanese (ja)
Inventor
輝 日高
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujikura Ltd
Original Assignee
Fujikura Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fujikura Ltd filed Critical Fujikura Ltd
Publication of WO2019189317A1 publication Critical patent/WO2019189317A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/02—Details
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • 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
    • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • 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
    • 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 a light detection device and a laser system, and more particularly to a light detection device for detecting laser light propagating through an optical fiber in a laser system such as a fiber laser.
  • the power of the laser light propagating through the core is measured by detecting the laser light propagating through the core of the optical fiber for system control or abnormality detection (for example, Patent Document 1).
  • system control or abnormality detection for example, Patent Document 1.
  • surplus light propagating through the clad may be detected as noise, and in such a case, the detection accuracy of the laser beam is lowered.
  • the recent increase in output of laser systems not only excess light inside the laser system but also laser light output from the laser system is reflected by the work piece and reflected back from the output end into the laser system. Light is also a problem as noise.
  • the present invention has been made in view of such problems of the prior art, and it is a first object of the present invention to provide a photodetector that can detect the output of laser light propagating through the core of an optical fiber with high accuracy. The purpose.
  • a second object of the present invention is to provide a laser system that can detect the output of laser light propagating through the core of an optical fiber with high accuracy.
  • a photodetector that can detect the output of the laser beam propagating through the core of the optical fiber with high accuracy.
  • the photodetector includes a core, an inner cladding that covers the outer periphery of the core and has a refractive index lower than the refractive index of the core, and an outer cladding that covers the outer periphery of the inner cladding and has a refractive index equal to or lower than the refractive index of the inner cladding.
  • An optical fiber including an outer cladding is provided.
  • the light detection device is disposed in a light detection region of the optical fiber, detects a laser beam propagating through the core of the optical fiber, and upstream of the light detection region of the optical fiber.
  • An upstream light removal unit that removes at least a part of excess light propagating outside the core of the optical fiber in at least a part of the upstream light removal region, and a downstream of the light detection region of the optical fiber.
  • a downstream light removal section for removing at least a part of the reflected light propagating outside the core of the optical fiber in at least a part of the downstream light removal region located on the side.
  • the “inner clad” in the present specification may be formed from a single layer or may be formed from a plurality of layers.
  • a photodetector that can detect the output of laser light propagating through the core of the optical fiber with high accuracy.
  • the photodetector includes a core, an inner cladding that covers the outer periphery of the core and has a refractive index lower than the refractive index of the core, and an outer cladding that covers the outer periphery of the inner cladding and has a refractive index equal to or lower than the refractive index of the inner cladding.
  • An optical fiber is provided that includes an outer cladding and a coating that covers an outer periphery of the outer cladding and has a refractive index that is equal to or higher than the refractive index of the outer cladding.
  • the light detection device is disposed in a light detection region of the optical fiber, detects a laser beam propagating through the core of the optical fiber, and upstream of the light detection region of the optical fiber. At least one of the excess light or the reflected light propagating outside the core of the optical fiber in at least a part of one of the upstream light removal area and the downstream light removal area located downstream.
  • the first light removal unit is a first resin formed on an outer periphery of the coating in at least a part of the one light removal region, and has a refractive index equal to or higher than a refractive index of the coating. Provide resin.
  • a laser system capable of detecting the output of laser light propagating through the core of an optical fiber with high accuracy.
  • This laser system includes a laser light source that generates laser light and the above-described light detection device.
  • the laser beam generated by the laser light source is input to the optical fiber of the photodetector.
  • FIG. 1 is a schematic diagram showing an overall configuration of a fiber laser as a laser system in the first embodiment of the present invention.
  • FIG. 2 is a diagram showing a cross section and a refractive index distribution of an optical fiber used in the fiber laser photodetection device shown in FIG.
  • FIG. 3 is a cross-sectional view schematically showing an upstream light removal unit of the fiber laser light detection device shown in FIG.
  • FIG. 4 is a cross-sectional view schematically showing a downstream light removal unit of the fiber laser light detection device shown in FIG.
  • FIG. 5 is a schematic diagram showing an overall configuration of a fiber laser as a laser system in the second embodiment of the present invention.
  • FIG. 6 is a cross-sectional view schematically showing an upstream light removal unit of the fiber laser light detection device shown in FIG.
  • FIG. 7 is a cross-sectional view schematically showing a downstream side light removal unit of the fiber laser light detection device shown in FIG.
  • FIG. 8 is a schematic diagram showing an overall configuration of a fiber laser as a laser system in the third embodiment of the present invention.
  • FIG. 9 is a cross-sectional view schematically showing an amplification optical fiber in the fiber laser of FIG.
  • FIG. 10 is a schematic diagram showing an overall configuration of a fiber laser as a laser system in the fourth embodiment of the present invention.
  • FIG. 11 is a schematic diagram showing a configuration of a photodetection device according to another embodiment of the present invention.
  • a fiber laser will be described as an example of the laser system according to the present invention.
  • the present invention is not limited to a fiber laser, and an arbitrary laser including a laser source that generates laser light. Applicable to the system. 1 to 11, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted. Further, in FIGS. 1 to 11, the scale and dimensions of each component are exaggerated, and some components may be omitted.
  • FIG. 1 is a schematic diagram showing an overall configuration of a fiber laser 1 as a laser system according to a first embodiment of the present invention.
  • the fiber laser 1 in the present embodiment includes an optical fiber amplifier 2 as a laser light source and a light detection device 30 that detects laser light output from the optical fiber amplifier 2.
  • the optical fiber amplifier 2 includes an optical resonator 10, a plurality of forward pumping light sources 20A that introduce pumping light into the optical resonator 10 from the front of the optical resonator 10, and a forward inline combiner to which these forward pumping light sources 20A are connected.
  • the optical resonator 10 includes an amplification optical fiber 12 having a core to which rare earth ions such as yttrium (Yb) and erbium (Er) are added, and a highly reflective fiber connected to the amplification optical fiber 12 and the front inline combiner 22A.
  • amplification optical fiber 12 having a core to which rare earth ions such as yttrium (Yb) and erbium (Er) are added, and a highly reflective fiber connected to the amplification optical fiber 12 and the front inline combiner 22A.
  • the amplification optical fiber 12 is composed of a double-clad optical fiber having an inner cladding formed around the core and an outer cladding formed around the inner cladding.
  • the front excitation light source 20A and the rear excitation light source 20B for example, a high-power multimode semiconductor laser (LD) having a wavelength of 915 nm can be used.
  • the front inline combiner 22A and the rear inline combiner 22B combine the pumping lights output from the front pumping light source 20A and the rear pumping light source 20B, respectively, and introduce them into the inner cladding of the amplification optical fiber 12 described above. Thereby, the excitation light propagates inside the inner cladding of the amplification optical fiber 12.
  • the HR-FBG 14 is formed by periodically changing the refractive index of an optical fiber, and reflects light in a predetermined wavelength band with a reflectance close to 100%.
  • the OC-FBG 16 is formed by periodically changing the refractive index of the optical fiber, and a part (for example, 10%) of light in the wavelength band reflected by the HR-FBG 14 is used. It passes through and reflects the rest. In this way, light that causes laser oscillation by recursively amplifying light in a specific wavelength band between the HR-FBG 14 and the OC-FBG 16 by the HR-FBG 14, the amplification optical fiber 12, and the OC-FBG 16 A resonator 10 is configured.
  • a light detection device 30 for detecting laser light is provided on the downstream side of the delivery fiber 24.
  • the light detection device 30 includes an optical fiber 34 connected to the delivery fiber 24.
  • the optical fiber 34 is connected to the delivery fiber 24 by a fusion splicing portion 32 as an input end, and laser light output from the delivery fiber 24 is introduced into the optical fiber 34 of the light detection device 30. ing.
  • a laser emitting unit 90 that emits laser light toward a workpiece is provided.
  • the optical fiber 34 may be a delivery fiber or a fiber having a core to which rare earth ions are added.
  • FIG. 2 is a view showing a cross section and a refractive index distribution of the optical fiber 34.
  • the optical fiber 34 is a double-clad optical fiber having a trench layer with a low refractive index. That is, the optical fiber 34 includes a core 40, an inner cladding 41 that covers the outer periphery of the core 40, a trench layer 42 that covers the outer periphery of the inner cladding 41, an outer cladding 43 that covers the outer periphery of the trench layer 42, and an outer cladding 43. And a coating 44 covering the outer periphery.
  • the refractive index of the inner cladding 41 is lower than the refractive index of the core 40, and the refractive index of the trench layer 42 is lower than the refractive indexes of the inner cladding 41 and the outer cladding 43.
  • the refractive index of the outer cladding 43 is equal to that of the inner cladding 41.
  • the refractive index of the coating 44 is equal to or higher than the refractive index of the outer cladding 43. Note that the refractive index of the outer cladding 43 may be lower than that of the inner cladding 41.
  • the light detection device 30 is disposed in the light detector 60 disposed in the vicinity of the light detection region 51 of the optical fiber 34 and the upstream light removal region 52 located upstream of the light detection region 51.
  • the upstream light removal unit 71 first or second light removal unit
  • the downstream light removal unit 72 second arranged in the downstream light removal region 53 located downstream of the light detection region 51. Or a first light removal unit).
  • the photodetector 60 in the present embodiment can detect the power of laser light propagating through the core 40 by detecting Rayleigh scattered light generated by light propagating through the optical fiber 34.
  • the fiber laser 1 also includes a control unit 80 that controls the excitation light sources 20A and 20B of the optical fiber amplifier 2 based on the power (output) of the laser light detected by the photodetector 60 of the light detection device 30. Yes.
  • the photodetector 60 outputs not only the laser light output from the optical fiber amplifier 2 and propagating through the core 40 of the optical fiber 34 but also the extra light propagating through the layers 41 to 44 outside the core 40 and the output from the fiber laser 1. There is a possibility that the Rayleigh scattered light caused by the reflected laser beam reflected by the workpiece or the like and reflected from the laser emitting unit 90 into the fiber laser 1 may be detected.
  • the upstream side light removing unit 71 and the downstream side light removing unit 72 are provided in order to reduce noise due to such excess light and reflected light.
  • “excess light” mainly means light in a direction from the optical fiber amplifier 2 toward the laser emitting unit 90
  • reflected light mainly means a direction from the laser emitting unit 90 toward the optical fiber amplifier 2. Means light.
  • the upstream light removal unit 71 and the downstream light removal unit 72 will be described in detail.
  • FIG. 3 is a cross-sectional view schematically showing the upstream light removal unit 71.
  • the upstream side light removal unit 71 in the present embodiment includes a housing 73 that houses the upstream light removal region 52 of the optical fiber 34, and a resin 75 (first member) housed inside the housing 73. 1 or 2nd resin).
  • the resin 75 is formed so as to cover the outer periphery of the coating 44 of the optical fiber 34, and has a refractive index equal to or higher than the refractive index of the coating 44 of the optical fiber 34.
  • the refractive index of the coating 44 covering the outer cladding 43 is equal to or higher than the refractive index of the outer cladding 43
  • the refractive index of the resin 75 covering the coating 44 is equal to or higher than the refractive index of the coating 44.
  • at least a portion L 1 leaks from the outer cladding 43 through the coating 44 to the resin 75, and a portion thereof is absorbed by the resin 75 and converted into heat. This heat is released to the outside from the housing 73 through a heat sink (not shown) connected to the housing 73.
  • the upstream light removal unit 71 in the upstream light removal unit 71, at least a part L 1 of the surplus light propagating through the outer cladding 43 is converted into heat, so that unnecessary surplus light L 1 is upstream of the light detection region 51. Can be removed by the upstream light removal region 52. As a result, the amount of excess light detected as noise by the photodetector 60 is reduced, and the detection accuracy of the photodetector 60 is improved.
  • FIG. 4 is a cross-sectional view schematically showing the downstream side light removal unit 72.
  • the downstream light removal unit 72 in the present embodiment includes a housing 74 that houses the downstream light removal region 53 of the optical fiber 34, and a resin 76 (first member) housed inside the housing 74. 2 or first resin).
  • the resin 76 is formed so as to cover the outer periphery of the coating 44 of the optical fiber 34, and has a refractive index equal to or higher than the refractive index of the coating 44 of the optical fiber 34.
  • the refractive index of the coating 44 covering the outer cladding 43 is equal to or higher than the refractive index of the outer cladding 43
  • the refractive index of the resin 76 covering the coating 44 is equal to or higher than the refractive index of the coating 44.
  • at least a part L 2 leaks from the outer cladding 43 through the coating 44 to the resin 76, and a part thereof is absorbed by the resin 76 and converted into heat. This heat is released to the outside from the housing 74 through a heat sink (not shown) connected to the housing 74.
  • the downstream light removal unit 72 converts at least a part L 2 of the reflected light propagating through the outer cladding 43 into heat, so that unnecessary reflected light L 2 is downstream of the light detection region 51.
  • the downstream light removal region 53 can remove the light. As a result, the amount of reflected light detected as noise by the photodetector 60 is reduced, and the detection accuracy of the photodetector 60 is improved.
  • At least a part L 1 of the surplus light propagating through the outer cladding 43 from the optical fiber amplifier 2 toward the laser emitting unit 90 reaches the upstream side before reaching the light detection region 51. Since it is removed by the light removal unit 71, it is suppressed that such excess light L 1 is detected as noise by the photodetector 60. Further, at least a part L 2 of the reflected light propagating through the outer cladding 43 from the laser emitting unit 90 toward the optical fiber amplifier 2 is removed by the downstream light removing unit 72 before reaching the light detection region 51. The reflected light L 2 is prevented from being detected as noise by the photodetector 60.
  • the detection accuracy of the photodetector 60 can be improved, and the output of the laser light propagating through the core 40 of the optical fiber 34 can be detected with high accuracy.
  • the control unit 80 controls the current supplied to the excitation light sources 20A and 20B by the control unit 80 using the highly accurate detection result obtained by such a light detection device 30, more accurate control of the fiber laser 1 is possible. It becomes. For example, as specific control, when the control unit 80 determines that the output of the laser light detected by the light detection device 30 is larger than a predetermined threshold, the control unit 80 reduces or zeros the output of the laser light.
  • the excitation light sources 20A and 20B may be controlled as follows.
  • control unit 80 determines that the output of the laser light detected by the light detection device 30 is smaller than a predetermined threshold different from the above-described threshold, the control unit 80 is excited so as to increase the output of the laser light.
  • the light sources 20A and 20B may be controlled.
  • the housing 73 in this embodiment is a light shielding unit (upstream light shielding unit or first light shielding unit or second light shielding unit) that blocks light that is removed by the resin 75 of the upstream light removal unit 71 and that travels toward the photodetector 60. Function as a light shielding portion).
  • the light shielding plate 81 may be provided so as to block light that is removed by the resin 75 of the upstream light removing unit 71 and that travels toward the photodetector 60.
  • the housing 74 in the present embodiment is a light-shielding part (downstream-side light-shielding part or second light-shielding part or first light-shielding part) that is removed by the resin 76 of the downstream-side light removal part 72 and blocks the light toward the photodetector 60. Function as a light shielding portion).
  • the reflected light removed with the resin 76 of the downstream light removal part 72 injects into the photodetector 60, and is detected as noise, and the detection accuracy of the photodetector 60 increases.
  • a part of the light removed by the resin 76 may be emitted to the outside of the casing 74 without providing the casing 74 with a portion that blocks the reflected light. Even in such a case, part of the light removed by the resin 76 is absorbed by the housing 74 and converted into heat.
  • a casing 74 for example, as shown in FIG. 1, as a light shielding portion between the downstream side light removing section 72 and the photodetector 60, as shown in FIG.
  • the light shielding plate 82 may be provided so as to block the light that is removed by the resin 76 of the downstream light removing unit 72 and that travels toward the photodetector 60.
  • the resins 75 and 76 having a refractive index equal to or higher than the refractive index of the coating 44 are formed on the outer periphery of the coating 44 of the optical fiber 34.
  • surplus light and reflected light propagating outside the core 40 of the optical fiber 34 can be removed. That is, the coating 44 of the optical fiber 34 can be removed and exposed, but the exposed glass portion in that case is extremely vulnerable to moisture, and when the coating 44 is removed, it is damaged by a blade or the like.
  • the possibility of damaging or breaking the outer cladding 43 can be reduced, and there is no problem of heat generation due to the coating remaining when the coating is removed. Further, when removing the coating of the optical fiber, it is necessary to pass the optical fiber through a coating remover, and it is difficult to provide a structure for removing excess light after the optical fiber is installed in the apparatus.
  • the upstream light removal unit 71 and the downstream light removal unit 72 can be formed even after the fiber laser 1 is assembled, and the upstream side and the downstream side of the light detection region of the optical fiber 34 can be formed. It can be formed in any place, and the degree of freedom in design is high.
  • Such a resin having a refractive index higher than the refractive index of the coating 44 on the outer periphery of the coating 44 of the optical fiber 34 may be provided on both the upstream side and the downstream side of the light detection region 51 as in the present embodiment.
  • the light detection region 51 may be provided on at least one of the upstream side and the downstream side.
  • the resin 75 of the upstream light removal unit 71 and the resin 76 of the downstream light removal unit 72 described above may have the same refractive index.
  • the refractive index of the resin 75 of the upstream light removal unit 71 and the refractive index of the resin 76 of the downstream light removal unit 72 are the same. It is conceivable that the reflected light tends to leak into the resin 76 of the downstream light removal unit 72 more rapidly than the extent that the excess light leaks into the resin 75 of the upstream light removal unit 71.
  • the refractive index of the resin 76 of the downstream light removal unit 72 lower than the refractive index of the resin 75 of the upstream light removal unit 71, the excess light leaks into the resin 75 of the upstream light removal unit 71. In contrast, the reflected light may be more gently leaked into the resin 76 of the downstream side light removing unit 72. In this case, it is possible to suppress the generation of excessive heat locally at the downstream side light removal unit 72. If necessary, the refractive index of the resin 75 of the upstream light removing unit 71 can be made lower than the refractive index of the resin 76 of the downstream light removing unit 72.
  • the length along the optical axis of the portion where the resin 75 is formed in the upstream light removal region 52 and the length along the optical axis of the portion where the resin 76 is formed in the downstream light removal region 53 are the same. May be.
  • the refractive index of the resin 75 of the upstream light removal unit 71 and the refractive index of the resin 76 of the downstream light removal unit 72 are the same, the surplus light is reflected by the resin 76 of the downstream light removal unit 72. It is conceivable that there is a tendency to leak more slowly into the resin 75 of the upstream side light removal unit 71 than to the extent of leaking out.
  • the length along the optical axis of the portion where the resin 75 is formed in the upstream light removal region 52 of the optical fiber 34 is the length along the optical axis of the portion where the resin 76 is formed in the downstream light removal region 53.
  • the length of the downstream light removal region 53 along the optical axis can be made longer than the length of the upstream light removal region 52 along the optical axis.
  • FIG. 5 is a schematic diagram showing an overall configuration of a fiber laser 101 as a laser system in the second embodiment of the present invention.
  • the fiber laser 101 in the present embodiment is the same as that in the first embodiment except that a fiber detection device 130 is provided instead of the light detection device 30 in the first embodiment.
  • the photodetection device 130 will be described in detail.
  • the optical fiber 34 of the light detection device 130 is connected to the delivery fiber 24 of the optical fiber amplifier 2 by the fusion splicing portion 32, and the laser light output from the delivery fiber 24 is introduced into the optical fiber 34 of the light detection device 130. It has become so.
  • the light detection device 130 includes a photodetector 60 disposed in the vicinity of the light detection region 151 of the optical fiber 34 and an upstream light removal disposed in the upstream light removal region 152 located upstream of the light detection region 151.
  • Unit 171 (first or second light removal unit) and downstream light removal unit 172 (second or first light removal unit) disposed in downstream light removal region 153 located downstream of light detection region 151 Part).
  • FIG. 6 is a cross-sectional view schematically showing the upstream light removal unit 171.
  • the upstream side light removal region 152 of the optical fiber 34 in this embodiment is bent with a predetermined bending diameter.
  • the upstream light removal unit 171 includes a housing 173 that houses the upstream light removal region 152 of the bent optical fiber 34 and a resin 175 (first or second resin) that is housed inside the housing 173. Including.
  • This resin 175 is formed so as to cover the outer periphery of the coating 44 of the bent optical fiber 34, and has a refractive index equal to or higher than the refractive index of the coating 44 of the optical fiber 34.
  • the outer side is the same as in the first embodiment. As shown in FIG. 6, at least a part L 3 of the surplus light propagating through the clad 43 leaks from the outer clad 43 through the coating 44 to the resin 175, and a part thereof is absorbed by the resin 175 and becomes heat. Converted.
  • the upstream light removal region 152 is bent at a predetermined bending diameter, at least a part L 4 of the surplus light propagating through the inner cladding 41 also has the trench layer 42, the outer cladding 43, and the coating 44 from the inner cladding 41. It leaks through the resin 175 and a part thereof is absorbed by the resin 175 and converted into heat. This heat is released to the outside from the housing 173 through a heat sink (not shown) connected to the housing 173.
  • the upstream light removal unit 171 at least a part of the excess light L 3 and L 4 propagating through the outer cladding 43 and the inner cladding 41 is converted into heat, so that unnecessary excess light L 3 , L 4 can be removed by the upstream light removal region 152 upstream of the light detection region 151.
  • the amount of excess light detected as noise by the photodetector 60 is reduced, and the detection accuracy of the photodetector 60 is improved.
  • FIG. 7 is a cross-sectional view schematically showing the downstream side light removal unit 172.
  • the downstream side light removal region 153 of the optical fiber 34 in this embodiment is bent with a predetermined bending diameter.
  • the downstream light removal unit 172 includes a housing 174 that houses the downstream light removal region 153 of the bent optical fiber 34 and a resin 176 (second or first resin) that is housed inside the housing 174. Including.
  • the resin 176 is formed so as to cover the outer periphery of the coating 44 of the bent optical fiber 34, and has a refractive index higher than the refractive index of the coating 44 of the optical fiber 34.
  • the refractive index of the coating 44 that covers the outer cladding 43 is equal to or higher than the refractive index of the outer cladding 43
  • the refractive index of the resin 176 that covers the coating 44 is equal to or higher than the refractive index of the coating 44, as in the first embodiment.
  • at least a part L 5 of the reflected light propagating through the clad 43 leaks from the outer clad 43 through the coating 44 to the resin 176, and a part thereof is absorbed by the resin 176 and becomes heat. Converted.
  • the downstream light removal region 153 is bent at a predetermined bending diameter, at least a part L 6 of the reflected light propagating through the inner cladding 41 also has the trench layer 42, the outer cladding 43, and the coating 44 from the inner cladding 41. It leaks through the resin 176 and part of it is absorbed by the resin 176 and converted into heat. This heat is released to the outside from the housing 174 through a heat sink (not shown) connected to the housing 174. In this way, in the downstream light removing unit 172, unnecessary reflected light L 5 , L 6 is converted into heat by converting at least a part of the reflected light L 5 and L 6 propagating through the outer cladding 43 and the inner cladding 41 into heat. L 6 can be removed by the downstream light removal region 153 downstream of the light detection region 151. As a result, the amount of reflected light detected as noise by the photodetector 60 is reduced, and the detection accuracy of the photodetector 60 is improved.
  • the resin 175, 176 having a refractive index equal to or higher than the refractive index of the coating 44 is formed on the outer periphery of the coating 44 of the optical fiber 34.
  • the optical fiber 34 can be prevented from breaking when the optical fiber 34 in the upstream light removal region 152 and the downstream light removal region 153 of the optical fiber 34 is bent. For example, when the optical fibers 34 in the upstream light removal region 152 and the downstream light removal region 153 are bent so that the bent portion protrudes in the upper direction in FIG. 3 or FIG.
  • the incident angle formed by the direction in which light enters the boundary surface between the two and the normal line of the boundary surface can be reduced, a structure in which excess light and reflected light can be more easily emitted from the optical fiber 34 to the outside. Can do. Accordingly, it is possible to increase the amount of excess light that can be removed by the upstream side light removing unit 171 and the amount of reflected light that can be removed by the downstream side light removing unit 172, and the excess light and reflected light that are detected as noise by the photodetector 60. The amount of can be further reduced. As described above, according to the light detection device 130 of the present embodiment, it is possible to efficiently remove excess light and reflected light.
  • the upstream light removal region 52 and the downstream light removal region 53 of the optical fiber 34 are not bent as in the first embodiment, the excess light and reflected light can be removed, but the excess light and reflected light.
  • the coating 44 remains in the portion where the optical fiber 34 is bent, the optical fiber 34 can be bent while maintaining the breaking strength, and excess light and reflected light can be efficiently removed.
  • the housing 173 in this embodiment is a light shielding unit (upstream light shielding unit or first light shielding unit or second light shielding unit) that blocks the light that is removed by the resin 175 of the upstream light removal unit 171 and that travels toward the photodetector 60. Function as a light shielding portion).
  • a part of the light removed by the resin 175 may be emitted to the outside of the housing 173 without providing the housing 173 with a portion that blocks excess light.
  • the housing 174 in this embodiment is a light shielding unit (downstream light shielding unit or second light shielding unit or first light shielding unit) that is removed by the resin 176 of the downstream light removing unit 172 and blocks light directed to the photodetector 60. Function as a light shielding portion).
  • a part of the light removed by the resin 176 may be emitted to the outside of the housing 174 without providing the housing 174 with a portion that blocks the reflected light. Even in such a case, part of the light removed by the resin 176 is absorbed by the housing 174 and converted into heat.
  • a light shielding plate may be provided as a downstream light shielding part. Further, the direction in which the optical fiber 34 is bent in the downstream light removal unit 172 may be adjusted so that the light removed by the resin 176 of the downstream light removal unit 172 does not go to the photodetector 60.
  • the upstream intermediate region 154 between the upstream light removal region 152 and the light detection region 151 of the optical fiber 34 is bent with a bending diameter smaller than the minimum bending diameter of the optical fiber 34 in the upstream light removal region 152.
  • Laser light propagating through the core 40 and surplus light propagating through the outer layers 41 to 44 of the core 40 leak to the outer layer (coating 44) or the outside, which is detected as noise by the photodetector 60, and is detected by light.
  • the accuracy of the device 60 may be reduced.
  • the minimum bending diameter of the optical fiber 34 in the upstream intermediate region 154 is larger than the minimum bending diameter of the optical fiber 34 in the upstream light removal region 152.
  • the upstream intermediate region 154 of the present embodiment is linear, and the minimum bending diameter of the upstream intermediate region 154 is infinite.
  • the reflected light is removed in the downstream light removal region 153 of the optical fiber 34, but the downstream intermediate region 155 between the downstream light removal region 153 and the light detection region 151 of the optical fiber 34. If any part of the second or first intermediate region (see FIG. 5) is bent with a bending diameter smaller than the minimum bending diameter of the optical fiber 34 in the downstream light removal region 153, the optical fiber 34.
  • the reflected light propagating through the core 40 leaks to the outer layer (coating 44) or the outside, which is detected as noise by the photodetector 60, and the accuracy of the photodetector 60 may be reduced.
  • the minimum bending diameter of the optical fiber 34 in the downstream intermediate region 155 is larger than the minimum bending diameter of the optical fiber 34 in the downstream light removal region 153.
  • the downstream intermediate region 155 of the present embodiment is linear, and the minimum bending diameter of the downstream intermediate region 155 is infinite.
  • the resin 175 of the upstream light removal unit 171 and the resin 176 of the downstream light removal unit 172 may have the same refractive index.
  • the refractive index of the resin 175 is equal to the refractive index of the resin 176, the reflected light may tend to leak into the resin 176 more rapidly than the excess light leaks into the resin 175. Conceivable.
  • the resin 176 of the downstream light removal unit 172 The refractive index may be lower than the refractive index of the resin 175 of the upstream light removal unit 171.
  • the refractive index of the resin 175 of the upstream light removal unit 171 may be lower than the refractive index of the resin 176 of the downstream light removal unit 172.
  • the length along the line may be the same.
  • the refractive index of the resin 175 and the refractive index of the resin 176 are equal, the excess light tends to leak into the resin 175 more slowly than the reflected light leaks into the resin 176. Can be considered.
  • the length along the optical axis of the portion where the resin 175 is formed may be longer than the length along the optical axis of the portion where the resin 176 is formed in the downstream light removal region 153.
  • the resin 176 is formed in the downstream light removal region 153 and the length along the optical axis of the portion is the length of the portion where the resin 175 is formed in the upstream light removal region 152. It may be longer than the length along the optical axis.
  • FIG. 8 is a schematic diagram showing an overall configuration of a fiber laser 201 as a laser system in the third embodiment of the present invention.
  • the fiber laser 201 in the present embodiment is a MOPA type fiber laser as an example of a fiber laser to which the present invention can be applied.
  • the fiber laser 201 includes an optical fiber amplifier 202 as a laser light source and the light detection device 30 described in the first embodiment.
  • the optical fiber amplifier 202 combines a signal light generator 210 that generates signal light, a plurality of pump light sources 220 that generate pump light, and signal light from the signal light generator 210 and pump light from the pump light source 220. And an optical fiber for amplification 212 having an end connected to the output end 214 of the optical coupler 222.
  • the light detection device 30 is connected to the amplification optical fiber 212 of the optical fiber amplifier 202 by a fusion splicing portion 232.
  • the fiber laser 201 also includes a control unit 280 that controls the pumping light source 220 of the optical fiber amplifier 202 based on the output of the laser light detected by the photodetector 60 of the light detection device 30.
  • FIG. 9 is a cross-sectional view schematically showing the amplification optical fiber 212.
  • the amplification optical fiber 212 includes a core 234 that propagates the signal light generated by the signal light generator 210, an inner cladding 236 formed around the core 234, and a periphery of the inner cladding 236. And an outer clad 238 formed in a double clad type optical fiber.
  • the core 234 is made of SiO 2 to which a rare earth element such as yttrium (Yb) is added, for example, and serves as a signal optical waveguide that propagates signal light.
  • Yb yttrium
  • the inner cladding 236 is made of a resin having a refractive index lower than that of the core 234 (for example, a low refractive index polymer). Thus, the inner cladding 236 becomes a pumping optical waveguide that propagates pumping light.
  • the signal light from the signal light generator 210 propagates inside the core 234 of the amplification optical fiber 212, and the excitation light from the excitation light source 220 propagates inside the inner cladding 236 and the core 234 of the amplification optical fiber 212.
  • the excitation light propagates through the core 234, the rare earth element ions added to the core 234 are excited by absorbing the excitation light, and the signal light propagating through the core 234 is amplified by stimulated emission.
  • the fiber laser 201 can be more accurately controlled.
  • the control unit 280 determines that the output of the laser light detected by the light detection device 30 is larger than a predetermined threshold, the control unit 280 reduces or reduces the output of the laser light.
  • the excitation light source 220 may be controlled as follows. Further, when the control unit 280 determines that the output of the laser light detected by the light detection device 30 is smaller than a predetermined threshold different from the above-described threshold, excitation is performed so that the control unit 280 increases the output of the laser light.
  • the light source 220 may be controlled.
  • FIG. 10 is a schematic diagram showing an overall configuration of a fiber laser 301 as a laser system in the fourth embodiment of the present invention.
  • This fiber laser 301 is a combination of the optical fiber amplifier 202 in the third embodiment and the light detection device 130 in the second embodiment. Even with such a configuration, at least a part of surplus light propagating through the outer cladding 43 from the optical fiber amplifier 202 toward the laser emitting unit 90 is removed by the upstream light removing unit 171 before reaching the light detection region 151. At the same time, at least a part of the reflected light propagating through the outer cladding 43 from the laser emitting unit 90 toward the optical fiber amplifier 202 is removed by the downstream light removing unit 172 before reaching the light detection region 151.
  • the photodetector 60 As a result, the detection accuracy of the photodetector 60 can be improved, and the output of the laser light propagating through the core 40 of the optical fiber 34 can be detected with high accuracy.
  • a light detector 460 (additional light detector) different from the light detector 60 is added to the additional light detection region 156 located upstream of the light removal region 152 upstream of the optical fiber 34. ) May be arranged.
  • the photodetector 60 and the photodetector 460 are connected to the controller 80, and the difference between the output of the laser beam detected by the upstream photodetector 460 and the output of the laser beam detected by the downstream photodetector 60 By calculating, the output of the laser beam propagating through the core 40 can be detected more accurately.
  • a light detector 460 a light detector that detects Rayleigh scattered light generated by light propagating through the optical fiber 34 can be used, similarly to the light detector 60. It goes without saying that such a configuration can also be applied to the above-described first to third embodiments.
  • the outer periphery of the outer cladding 43 is covered with the coating 44 over the outer cladding 43 as the upstream light removal units 71, 171 and the downstream light removal units 72, 172, and the outer periphery of the coating 44 is over the coating 44.
  • the structures that can be used as the upstream light removal units 71 and 171 and the downstream light removal units 72 and 172 are not limited to this.
  • a structure in which a part of the coating of the double clad optical fiber is removed and the outer periphery of the exposed outer clad is covered with a resin having a refractive index higher than that of the outer clad or Japanese Patent Application Laid-Open No.
  • a structure that removes excess light and reflected light by forming a spiral groove on the outer peripheral surface of the optical fiber has an upstream light removing unit 71,171 and a downstream light removing unit 72, It can also be adopted as 172.
  • both the upstream light removal unit 71 and the downstream light removal unit 72 are provided.
  • the upstream light removal unit 71 and the downstream side are described. Only one of the light removal units 72 may be provided.
  • both the upstream light removal unit 171 and the downstream light removal unit 172 are provided is described.
  • the upstream light removal unit 171 and the downstream light removal unit 172 are provided. Only one of the side light removing units 172 may be provided.
  • a photodetector that detects Rayleigh scattered light generated by light propagating through the optical fiber 34 is used as the photodetectors 60 and 460 in the photodetectors 30 and 130 .
  • the photodetector and the additional photodetector according to the present invention are not limited to this, and for example, a photodetector using a photodiode may be used.
  • the example in which the optical fiber amplifiers 2 and 202 in the fiber laser are used as the laser light sources of the fiber lasers 1, 101, 201, and 301 as the laser system has been described. Is not limited to this, and for example, a CO 2 laser light source can be used.
  • the example in which the light detection devices 30 and 130 are provided on the downstream side of the optical resonator 10 of the fiber lasers 1, 101, 201, and 301 as the laser system has been described.
  • the position of 130 is not limited to this, and the optical detection devices 30 and 130 may be installed inside the optical resonator 10, or the optical detection devices 30 and 130 may be installed upstream of the optical resonator 10. May be.
  • a photodetector that can detect the output of the laser beam propagating through the core of the optical fiber with high accuracy.
  • the photodetector includes a core, an inner cladding that covers the outer periphery of the core and has a refractive index lower than the refractive index of the core, and an outer cladding that covers the outer periphery of the inner cladding and has a refractive index equal to or lower than the refractive index of the inner cladding.
  • An optical fiber including an outer cladding is provided.
  • the light detection device is disposed in a light detection region of the optical fiber, detects a laser beam propagating through the core of the optical fiber, and upstream of the light detection region of the optical fiber.
  • An upstream light removal unit that removes at least a part of excess light propagating outside the core of the optical fiber in at least a part of the upstream light removal region, and a downstream of the light detection region of the optical fiber.
  • a downstream light removal section for removing at least a part of the reflected light propagating outside the core of the optical fiber in at least a part of the downstream light removal region located on the side.
  • the upstream light removal unit can remove at least a part of excess light propagating outside the optical fiber core in the upstream light removal region upstream of the light detection region.
  • the amount of excess light detected as noise by the detector can be reduced.
  • the downstream light removal unit can remove at least part of the reflected light propagating outside the optical fiber core in the downstream light removal region downstream of the light detection region.
  • the amount of reflected light detected as can be reduced.
  • the amount of excess light and reflected light detected as noise by the photodetector can be reduced, so that the detection accuracy of the photodetector can be improved, and the laser light propagating through the core of the optical fiber can be reduced. It can be detected with high accuracy.
  • the optical fiber may include a coating that covers the outer cladding and has a refractive index equal to or higher than the refractive index of the outer cladding.
  • the upstream light removal portion is a first resin formed on the outer periphery of the coating in at least a part of the upstream light removal region of the optical fiber, and has a refractive index equal to or higher than the refractive index of the coating.
  • a first resin having a refractive index may be provided.
  • the refractive index of the coating covering the outer cladding is equal to or greater than the refractive index of the outer cladding, and the extra light propagating through the outer cladding by covering the coating with the first resin having a refractive index equal to or higher than the refractive index of the coating. At least a part of can be removed by leaking from the outer cladding to the first resin through the coating. Moreover, since it is not necessary to remove the coating of the optical fiber to expose the cladding in order to remove excess light and reflected light, the possibility of damaging the outer cladding can be reduced.
  • the upstream light removal region of the optical fiber is bent with a predetermined bending diameter.
  • the excess light propagating in the optical fiber is likely to leak to the outer layer or the outside, so that the amount of excess light that can be removed by the upstream light removal unit can be increased.
  • the amount of surplus light detected as noise by the detector can be further reduced.
  • the minimum bending diameter of the optical fiber in the upstream intermediate region between the upstream light removal region and the light detection region of the optical fiber is smaller than the minimum bending diameter of the optical fiber in the upstream light removal region. Is also preferably large.
  • the amount of light leaking to the outer layer or the outside can be suppressed to be less than the amount of light leaking to the outer layer or the outside in the upstream light removal region, and the light detector leaks by the light leaking to the outer layer or the outside. It is suppressed that the precision of this falls.
  • the downstream light removal unit is a second resin formed on the outer periphery of the coating in at least a part of the downstream light removal region of the optical fiber, and has a refractive index equal to or higher than the refractive index of the coating.
  • a second resin may be provided.
  • At least a part of the downstream light removal region of the optical fiber is bent with a predetermined bending diameter.
  • the light propagating outside the core of the optical fiber is likely to leak to the outside, so that the amount of reflected light that can be removed by the downstream light removal unit can be increased, and the photodetector Thus, the amount of reflected light detected as noise can be further reduced.
  • the minimum bending diameter of the optical fiber in the downstream intermediate region between the downstream light removal region and the light detection region of the optical fiber is smaller than the minimum bending diameter of the optical fiber in the downstream light removal region. Is also preferably large.
  • the refractive index of the second resin in the downstream light removal unit may be lower than the refractive index of the first resin in the upstream light removal unit.
  • the reflected light has a larger spread of light than the surplus light. Therefore, when the refractive index of the first resin and the refractive index of the second resin are equal, the surplus light is the first light. It is conceivable that there is a tendency to leak more rapidly into the second resin than in the case of leaking into the second resin. Therefore, by making the refractive index of the second resin lower than the refractive index of the first resin, the reflected light is more gently applied to the second resin than when excess light leaks into the first resin. Can be leaked. Therefore, it is possible to suppress the generation of excessive heat locally at the downstream light removal unit.
  • the length along the optical axis of the portion of the optical fiber where the first resin is formed is longer than the length along the optical axis of the portion of the optical fiber where the second resin is formed. May be.
  • the refractive index of the first resin and the refractive index of the second resin are equal, the excess light is more gently transferred to the first resin than when the reflected light leaks into the second resin. There is a tendency to leak.
  • the excess light is Since the area leaked into the first resin can be secured wider than the area where the reflected light leaks into the second resin, surplus light can be leaked more reliably into the first resin.
  • the light detection device may include an upstream light shielding unit that blocks light that is removed by the upstream light removal unit and that travels toward the photodetector.
  • an upstream light shielding unit that blocks light that is removed by the upstream light removal unit and that travels toward the photodetector.
  • the light detection device may include a downstream light shielding unit that blocks light that is removed by the downstream light removal unit and that travels toward the photodetector.
  • a downstream side light shielding part By such a downstream side light shielding part, it is possible to suppress the reflected light removed by the second resin of the downstream side light removing part from entering the photodetector and being detected as noise. Detection accuracy increases.
  • a photodetector that can detect the output of laser light propagating through the core of the optical fiber with high accuracy.
  • the photodetector includes a core, an inner cladding that covers the outer periphery of the core and has a refractive index lower than the refractive index of the core, and an outer cladding that covers the outer periphery of the inner cladding and has a refractive index equal to or lower than the refractive index of the inner cladding.
  • An optical fiber is provided that includes an outer cladding and a coating that covers an outer periphery of the outer cladding and has a refractive index that is equal to or higher than the refractive index of the outer cladding.
  • the light detection device is disposed in a light detection region of the optical fiber, detects a laser beam propagating through the core of the optical fiber, and upstream of the light detection region of the optical fiber. At least one of the excess light or the reflected light propagating outside the core of the optical fiber in at least a part of one of the upstream light removal area and the downstream light removal area located downstream.
  • the first light removal unit is a first resin formed on an outer periphery of the coating in at least a part of the one light removal region, and has a refractive index equal to or higher than a refractive index of the coating. Provide resin.
  • the first resin having a refractive index equal to or higher than the refractive index of the coating is formed on the outer periphery of the coating of the optical fiber in one of the upstream light removal region and the downstream light removal region. Only the excess light or the reflected light propagating outside the core of the optical fiber can be removed. Therefore, since it is not necessary to remove the coating of the optical fiber to expose the clad in order to remove excess light and reflected light, it is possible to reduce the possibility of damaging the outer clad.
  • At least a part of excess light propagating outside the optical fiber core in the upstream light removal region upstream of the light detection region, or in the downstream light removal region downstream of the light detection region Since at least a part of the reflected light propagating outside the core can be removed, the amount of surplus light or reflected light detected as noise by the photodetector can be reduced. In this way, since the amount of excess light or reflected light detected as noise by the photodetector can be reduced, the detection accuracy of the photodetector can be improved, and the laser light propagating through the core of the optical fiber can be reduced. It can be detected with high accuracy.
  • At least a part of the one light removal region of the optical fiber is bent with a predetermined bending diameter.
  • surplus light or reflected light propagating in the optical fiber easily leaks to the outer layer or the outside, so that the amount of surplus light or reflected light that can be removed by the light removing unit is increased.
  • the amount of surplus light or reflected light detected as noise by the photodetector can be further reduced.
  • the minimum bending diameter of the optical fiber in the first intermediate region between the one light removal region and the light detection region of the optical fiber is the minimum bending diameter of the optical fiber in the one light removal region. Is preferably larger. In this way, by setting the minimum bending diameter of the optical fiber in the first intermediate region to be larger than the minimum bending diameter of the optical fiber in the one light removal region, the distance between the one light removal region and the light detection region is increased. The amount of light leaking to the outer layer or the outside can be suppressed to be less than the amount of light leaking to the outer layer or the outside in the upstream light removal region. A reduction in the accuracy of the photodetector is suppressed.
  • the light detection device may include a first light shielding unit that blocks light that is removed by the first light removal unit and that travels toward the photodetector.
  • a first light shielding part With such a first light shielding part, it is possible to suppress the light removed by the resin of the first light removing part from entering the photodetector and being detected as noise, and the detection accuracy of the photodetector Will increase.
  • the light detection device includes at least one of excess light or reflected light propagating outside the core of the optical fiber in the other light removal region of the upstream light removal region and the downstream light removal region of the optical fiber. You may further provide the 2nd light removal part which removes one part.
  • the second light removal unit is a second resin formed on the outer periphery of the coating in the other light removal region, and includes a second resin having a refractive index equal to or higher than the refractive index of the coating. May be. With such a configuration, the second resin having a refractive index equal to or higher than the refractive index of the coating is formed on the outer periphery of the coating of the optical fiber in the other of the upstream light removal region and the downstream light removal region.
  • At least a part of the other light removal region of the optical fiber is bent with a predetermined bending diameter.
  • the light propagating outside the optical fiber core easily leaks to the outside, so that the amount of reflected light that can be removed by the other light removal unit can be increased, and light detection can be performed.
  • the amount of reflected light detected as noise by the instrument can be further reduced.
  • the minimum bending diameter of the optical fiber in the second intermediate region between the other light removal region and the light detection region of the optical fiber is the minimum bending diameter of the optical fiber in the other light removal region. Is preferably larger. In this way, by setting the minimum bending diameter of the optical fiber in the second intermediate region to be larger than the minimum bending diameter of the optical fiber in the other light removal region, the distance from the other light removal region to the light detection region is increased. Thus, the light propagating through the optical fiber is suppressed from leaking to the outer layer or the outside, and the accuracy of the photodetector is suppressed from being lowered by the light leaking to the outer layer or the outside.
  • the light detection device may include a second light shielding unit that blocks light that is removed by the second light removal unit and that travels toward the photodetector.
  • a second light shielding part it is possible to suppress the light removed by the resin of the second light removing part from entering the photodetector and being detected as noise, and the detection accuracy of the photodetector Will increase.
  • the refractive index of the second resin or the first resin formed in the downstream light removal region is the refractive index of the first resin or the second resin formed in the upstream light removal region. May be lower. In general, reflected light has a larger spread of light than surplus light. Therefore, when the refractive index of the first resin is equal to the refractive index of the second resin, the reflected light is not absorbed by the resin. It can be considered that there is a tendency to leak into the resin more rapidly than the leakage. Therefore, by making the refractive index of the resin formed in the downstream light removal region lower than the refractive index of the resin formed in the upstream light removal region, it is more gradual than excess light leaks into the resin. Reflected light can be leaked into the resin. Therefore, it is possible to suppress the generation of excessive heat locally at the downstream light removal unit.
  • the length along the optical axis of the portion where the first resin or the second resin is formed in the upstream light removal region of the optical fiber is the downstream light removal region of the optical fiber. May be longer than the length along the optical axis of the portion where the second resin or the first resin is formed. For example, if the refractive index of the first resin and the refractive index of the second resin are equal, the surplus light tends to leak into the resin more slowly than the reflected light leaks into the resin. Can be considered. Therefore, the length along the optical axis of the portion where the first resin or the second resin is formed in the upstream light removal region of the optical fiber is set to the length of the second resin or the first resin in the downstream light removal region.
  • the light detector may be configured to detect Rayleigh scattered light generated by light propagating through the optical fiber.
  • the light detection device may further include an additional light detector disposed in an additional light detection region located upstream of the upstream light removal region of the optical fiber.
  • the additional light detection device detects laser light propagating through the core of the optical fiber, and may be configured to detect, for example, Rayleigh scattered light generated by light propagating through the optical fiber. . According to such a configuration, by calculating the difference between the output of the laser beam detected by the upstream side additional photodetector and the output of the laser beam detected by the downstream side photodetector, the light is more accurately detected. The output of the laser beam propagating through the fiber core can be detected.
  • the optical fiber may be a trench layer having a refractive index lower than that of the inner cladding and the outer cladding, and further includes a trench layer positioned between the inner cladding and the outer cladding. Good. Such a trench layer suppresses surplus light emitted outside the trench layer from returning to the inner cladding, so that the surplus light can be efficiently removed in the light removal section.
  • a laser system capable of detecting the output of laser light propagating through the core of an optical fiber with high accuracy.
  • This laser system includes a laser light source that generates laser light and the above-described light detection device.
  • the laser beam generated by the laser light source is input to the optical fiber of the photodetector.
  • the photodetector according to the first aspect described above when the photodetector according to the first aspect described above is incorporated in a laser system, at least a part of the surplus light of the laser light generated by the laser light source and the laser light output from the laser system are processed. It is possible to detect the output of the laser beam propagating through the optical fiber core while removing at least part of the reflected light reflected back to the laser system. The output of the laser beam to be detected can be detected with high accuracy.
  • the photodetector according to the second aspect described above is incorporated into a laser system, it is not necessary to expose the outer cladding of the optical fiber, so that the possibility of damaging the outer cladding can be reduced [0]. Thus, it is possible to realize a laser system capable of accurately detecting laser light propagating through the core of the optical fiber.
  • the laser system further includes a control unit that controls the laser light source based on laser light detected by the light detector of the light detection device.
  • the control accuracy of the laser system is improved by controlling the laser light source based on the output of the laser beam detected by the photodetector of the photodetection device with improved detection accuracy.
  • the upstream light removal unit can remove at least a part of the extraneous light propagating outside the optical fiber core, and the downstream light removal unit can reflect outside the optical fiber core. Since at least a part of the light can be removed, the amount of excess light and reflected light detected as noise by the photodetector can be reduced. Therefore, the detection accuracy of the photodetector can be improved, and the output of the laser light propagating through the core of the optical fiber can be detected with high accuracy.
  • surplus light or reflected light propagating outside the optical fiber core can be obtained only by forming the first resin having a refractive index equal to or higher than the refractive index of the coating on the outer periphery of the optical fiber coating. Since at least a part can be removed, it is not necessary to remove the coating of the optical fiber and expose the cladding in order to remove excess light and reflected light. Therefore, the possibility of damaging the outer cladding can be reduced.
  • the present invention is suitably used for a light detection device for detecting laser light propagating through an optical fiber in a laser system such as a fiber laser.

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Lasers (AREA)

Abstract

La présente invention concerne un dispositif photodétecteur capable de détecter, avec une précision élevée, une lumière laser qui se propage à travers une âme de fibre optique. Un dispositif photodétecteur (30) comprend une fibre optique (34) qui comprend une âme (40), une gaine interne (41) qui possède un indice de réfraction inférieur à l'indice de réfraction de l'âme (40), et une gaine externe (43) qui possède un indice de réfraction inférieur ou égal à l'indice de réfraction de la gaine interne (41). Le dispositif photodétecteur (30) comprend en outre : un photodétecteur (60) qui est disposé dans une région de photodétecteur (51) de la fibre optique (34) et détecte la lumière laser qui se propage à travers l'âme (40) de la fibre optique (34) ; une unité d'élimination de lumière en amont (72) qui élimine, dans une région d'élimination de lumière en amont (52) positionnée en amont de la région de photodétecteur (51) de la fibre optique (34), au moins une partie L1 de la lumière résiduelle qui se propage à travers l'extérieur de l'âme (40) de la fibre optique (34) ; et une unité d'élimination de lumière en aval (72) qui élimine, dans une région d'élimination de lumière en aval (53) positionnée en aval de la région de photodétecteur (51) de la fibre optique (34), au moins une partie L2 de la lumière réfléchie qui se propage à travers l'extérieur de l'âme (40) de la fibre optique (34).
PCT/JP2019/013105 2018-03-29 2019-03-27 Dispositif photodétecteur et système laser Ceased WO2019189317A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2018063625 2018-03-29
JP2018063690 2018-03-29
JP2018-063625 2018-03-29
JP2018-063690 2018-03-29

Publications (1)

Publication Number Publication Date
WO2019189317A1 true WO2019189317A1 (fr) 2019-10-03

Family

ID=68060675

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2019/013105 Ceased WO2019189317A1 (fr) 2018-03-29 2019-03-27 Dispositif photodétecteur et système laser

Country Status (1)

Country Link
WO (1) WO2019189317A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2021061344A (ja) * 2019-10-08 2021-04-15 株式会社フジクラ レーザ装置及びレーザ装置の光源制御方法
CN115152103A (zh) * 2020-03-10 2022-10-04 株式会社藤仓 光纤激光装置

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04291213A (ja) * 1991-03-19 1992-10-15 Fujikura Ltd 迷光除去装置
US20070217738A1 (en) * 2006-03-16 2007-09-20 Northrop Grumman Corporation System and method to remove light from cladding
JP2012014173A (ja) * 2010-06-30 2012-01-19 Jds Uniphase Corp スケーラブルなクラッド・モード・ストリッパ装置
US20140313513A1 (en) * 2013-04-23 2014-10-23 Kai-Hsiu Liao Power monitor for optical fiber using background scattering
US20140363125A1 (en) * 2013-06-06 2014-12-11 Prima Electro North America, LLC Cladding mode stripper
CN204116642U (zh) * 2014-09-19 2015-01-21 深圳朗光科技有限公司 一种光纤包层残余光能量滤除器及光纤合束器
JP2016161867A (ja) * 2015-03-04 2016-09-05 株式会社フジクラ 光パワーモニタ装置およびファイバレーザ装置
JP2017021099A (ja) * 2015-07-08 2017-01-26 株式会社フジクラ 光パワーモニタ装置およびファイバレーザ装置
JP2017116465A (ja) * 2015-12-25 2017-06-29 株式会社フジクラ 拡がり角測定装置、拡がり角測定方法、及びファイバレーザ装置

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04291213A (ja) * 1991-03-19 1992-10-15 Fujikura Ltd 迷光除去装置
US20070217738A1 (en) * 2006-03-16 2007-09-20 Northrop Grumman Corporation System and method to remove light from cladding
JP2012014173A (ja) * 2010-06-30 2012-01-19 Jds Uniphase Corp スケーラブルなクラッド・モード・ストリッパ装置
US20140313513A1 (en) * 2013-04-23 2014-10-23 Kai-Hsiu Liao Power monitor for optical fiber using background scattering
US20140363125A1 (en) * 2013-06-06 2014-12-11 Prima Electro North America, LLC Cladding mode stripper
CN204116642U (zh) * 2014-09-19 2015-01-21 深圳朗光科技有限公司 一种光纤包层残余光能量滤除器及光纤合束器
JP2016161867A (ja) * 2015-03-04 2016-09-05 株式会社フジクラ 光パワーモニタ装置およびファイバレーザ装置
JP2017021099A (ja) * 2015-07-08 2017-01-26 株式会社フジクラ 光パワーモニタ装置およびファイバレーザ装置
JP2017116465A (ja) * 2015-12-25 2017-06-29 株式会社フジクラ 拡がり角測定装置、拡がり角測定方法、及びファイバレーザ装置

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2021061344A (ja) * 2019-10-08 2021-04-15 株式会社フジクラ レーザ装置及びレーザ装置の光源制御方法
JP7304789B2 (ja) 2019-10-08 2023-07-07 株式会社フジクラ レーザ装置及びレーザ装置の光源制御方法
CN115152103A (zh) * 2020-03-10 2022-10-04 株式会社藤仓 光纤激光装置

Similar Documents

Publication Publication Date Title
US5659644A (en) Fiber light source with multimode fiber coupler
US11073656B2 (en) Optical coupler and optical amplifier
EP3070791B1 (fr) Dispositif laser à fibre
JP5260885B2 (ja) 光ファイバの漏洩光処理構造
CN204621354U (zh) 光纤激光器装置
CN110418992B (zh) 包层模光除去构造和激光装置
CN111183341B (zh) 光检测装置以及激光装置
CN110364919B (zh) 光纤激光装置
JP6550494B1 (ja) 光デバイスおよびファイバレーザ装置
JP2015149369A (ja) ファイバレーザ装置
WO2019189317A1 (fr) Dispositif photodétecteur et système laser
US20190229489A1 (en) Optical fiber and fiber laser
JP6734683B2 (ja) 光モニタ装置及びレーザ装置
US12142889B2 (en) Methods for SRS protection of laser components and apparatus providing SRS protection
WO2020045569A1 (fr) Structure de suppression de lumière de mode de gaine, dispositif laser, et procédé de fabrication d'une structure de suppression de lumière de mode gaine
JP2021136242A (ja) ファイバレーザ装置
WO2019172398A1 (fr) Dispositif d'élimination de lumière en excès et laser à fibre
JP2021150527A (ja) ファイバレーザ装置
WO2020203136A1 (fr) Dispositif laser à fibre
JP7288394B2 (ja) ファイバヒューズ検出装置、及びこれを用いたレーザ装置
EP1685633A1 (fr) Attenuation du signal optique par reseau de bragg a periode longue
KR20180092278A (ko) 파이버 레이저
WO2020105553A1 (fr) Structure de dénudage de lumière de mode gaine et dispositif laser

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19776733

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 19776733

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP