WO2007108391A1 - Fibre a double gaine et laser a fibre l'utilisant - Google Patents

Fibre a double gaine et laser a fibre l'utilisant Download PDF

Info

Publication number
WO2007108391A1
WO2007108391A1 PCT/JP2007/055164 JP2007055164W WO2007108391A1 WO 2007108391 A1 WO2007108391 A1 WO 2007108391A1 JP 2007055164 W JP2007055164 W JP 2007055164W WO 2007108391 A1 WO2007108391 A1 WO 2007108391A1
Authority
WO
WIPO (PCT)
Prior art keywords
fiber
core
clad
cladding
double
Prior art date
Application number
PCT/JP2007/055164
Other languages
English (en)
Japanese (ja)
Inventor
Tetsuya Yamamoto
Hisashi Sawada
Tomohiko Ishida
Kunio Yoshida
Tomosumi Kamimura
Original Assignee
Mitsubishi Cable Industries, 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 Mitsubishi Cable Industries, Ltd. filed Critical Mitsubishi Cable Industries, Ltd.
Publication of WO2007108391A1 publication Critical patent/WO2007108391A1/fr

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/032—Optical fibres with cladding with or without a coating with non solid core or cladding
    • 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
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03622—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only
    • 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
    • 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
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • 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
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • H01S3/06729—Peculiar transverse fibre profile
    • H01S3/06741—Photonic crystal fibre, i.e. the fibre having a photonic bandgap
    • 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
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • H01S3/06745—Tapering of the fibre, core or active region
    • 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
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
    • 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
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
    • H01S3/094007—Cladding pumping, i.e. pump light propagating in a clad surrounding the active core

Definitions

  • the present invention relates to a double clad fiber used for a high-power fiber laser.
  • a double clad fiber which is a type of optical fiber, has a core doped with a rare earth element as an optical amplification component from the center of the fiber, a first clad provided to cover the core and having a lower refractive index than the core, A second cladding having a lower refractive index than that of the first cladding.
  • the excitation light incident on the first cladding propagates through the region surrounded by the second cladding while repeatedly reflecting at the interface between the first and second claddings.
  • the rare earth element doped in the core is turned into an inverted distribution excited by its outermost electrons, and the light propagating through the core can be amplified by the stimulated emission.
  • Japanese Patent Application Laid-Open No. 11-1 14 2 6 7 2 proposes a double clad fiber having an air clad structure in which the second clad is formed by a plurality of fine holes.
  • an L D (laser diode) that emits pumping light is arranged at one fiber end.
  • the double clad fiber having the above air clad structure is superior in heat resistance to the conventional double clad fiber in which the second clad is formed of a resin having a low refractive index, and the first clad and the second clad. It is possible to design a large numerical aperture by increasing the difference in refractive index.
  • high-power lasers have become an important technology in production and processing in all industries, including space and aviation electronics, so double-clad fibers with the above-mentioned air-clad structure with high heat resistance. High-power lasers are also desired for fiber lasers that use the laser.
  • the present invention has been made in view of such points, and an object of the present invention is to provide a fiber laser having a higher output than the conventional one by improving a double-clad fiber having a high heat resistance and an air-clad structure. is there. Disclosure of the invention
  • a reflecting portion and a reflecting film are provided on each fiber end face.
  • the diameters of the core, the first cladding, and the second cladding are increased from one fiber end to the other fiber end.
  • a double clad fiber according to the present invention includes a core doped with a light enhancement component, a ⁇ 1 clad provided to cover the core, and the core provided to cover the first clad.
  • one of the fiber end faces is provided with an exit-side reflecting section that reflects a part of the light propagating through the core, and the other fiber end face is provided with the exit-side reflecting section. Reflected by Characterized that you have an incident-side reflecting film is provided for reflecting light propagating through the core.
  • the exit-side reflecting portion and the incident-side reflecting film are directly on each fiber end face. Since it is provided, for example, optical adjustment at the time of coupling with other optical elements such as a lens constituting a fiber laser and an excitation light source becomes easy.
  • the core diameter is usually about 10 to 100 ⁇ . it is difficult to element and forming 5 engaged.
  • the optical adjustment with the optical elements constituting the fiber laser becomes easy, so the double-clad fiber having a high heat resistance air-clad structure is improved, and a fiber laser having a higher output than before is provided. Is possible.
  • both fiber end faces are sealed and polished.
  • An exit-side reflecting portion and an incident-side reflecting film may be provided on both ends of the sealed and polished fiber. According to this, compared to the case where the exit-side reflecting portion and the incident-side reflecting film are provided on both end surfaces of the fiber that are not sealed and polished, that is, each of the creep surfaces of only the cut, the exit-side reflecting portion and the incident side The laser resistance of the side reflection film is improved.
  • the exit-side reflecting portion may be formed of a reflecting film.
  • the emission-side reflection unit is specifically configured by the reflection film that reflects light of a predetermined wavelength with low reflectance.
  • the double clad fiber according to the present invention includes a core doped with an optical amplification component, an i-th clad provided so as to cover the core, and a first clad provided so as to cover the first clad.
  • the second cluster formed with a plurality of pores extending along the core
  • the excitation light incident on the first cladding propagates in the region surrounded by the second cladding while repeatedly reflecting at the interface between the first cladding and the second cladding, and the excitation light Is a double-clad fiber configured to activate a light amplification component of the core when passing through the core, and the light amplification component amplifies light propagating through the core.
  • the diameters of the clad and second clad are
  • the diameter of the core and the first cladding is increased while maintaining a similar shape from one fiber end to the other fiber end.
  • the core, the first cladding, and the second cladding have similar shapes from the one fiber end toward the other fiber end.
  • the diameter is increased in a tapered manner along the length direction from the incident side of the excitation light
  • the second cladding has an air cladding structure including a plurality of pores.
  • the numerical aperture of the first cladding increases continuously along the length direction from the incident side of the excitation light. Therefore, leakage of the excitation light propagating through the first cladding to the outside is suppressed.
  • an emission-side reflecting portion for reflecting a part of light propagating through the core is provided at one fiber end, and light that is reflected by the emission-side reflecting portion at the other fiber end and propagates through the core.
  • the output-side reflecting portion When the resonator is configured by providing an incident-side reflecting film that reflects light, the output-side reflecting portion generates the inside of the core by the excitation light incident on the first cladding from the other fiber end surface. A part of the light propagating through one of the fiber ends toward one end of the fiber is reflected, and the light that is reflected by the incident-side reflecting film at the exit-side reflecting portion and propagates in the core toward the other fiber end Is reflected and propagates again toward one end of the fiber.
  • the light propagating through the core of the double clad fiber is laser-oscillated by amplification and resonance between the exit-side reflecting portion and the entrance-side reflecting film, and is emitted from the core at one fiber end.
  • a fiber laser is constructed.
  • the diameter of the core is reduced in a taper shape along the length direction from the incident side of the excitation light, among the light propagating in the core, the light in the higher order mode propagates in the core.
  • the low-order mode light mainly resonates between the exit shell reflection portion and the incident side reflection film, and the beam quality of the oscillated laser is improved.
  • higher-order mode light is also resonated, which may degrade the beam quality.
  • the core diameter remains small along the length direction, the absorption coefficient of the excitation light propagating through the first cladding may be reduced.
  • the diameter of the other fiber end on which the excitation light is incident becomes larger than the diameter of the one fiber end, for example, coupling with an excitation light source that outputs the excitation light becomes easy. Therefore, the leakage of the pumping light propagating through the first cladding is suppressed, the beam quality of the laser oscillated when the fiber laser is configured is improved, and the coupling with the pumping light source is facilitated.
  • High performance air clad structure It is possible to improve the lad fiber and provide a fiber laser with higher output than before.
  • the surface of one of the fiber ends above one side reflection film is provided for reflecting light propagating through the core, the surface of the other fiber end, is reflected of 5 above one side reflective film above An exit-side reflecting portion that reflects part of the light propagating through the core may be provided.
  • the one-side reflecting film provided on the one fiber end face generates the inside of the core by the excitation light incident on the first clad from the other fiber end face, and the inside of the core passes through the one fiber end face. While the light propagating towards is reflected, the other. A part of the light reflected by the reflection film on one side and propagating in the core toward the other fiber end is reflected by the output side reflection part provided on the fiber end surface of the fiber and propagates again toward the one fiber end. Will do.
  • the light propagating through the core of the double clad fiber is laser-oscillated by amplification and resonance between the exit-side reflecting portion and the one-side reflecting film, and is emitted from the core at the other fiber end.
  • a laser beam is emitted from the end of the fiber having a large fiber diameter, and a fiber on the emission side is emitted.
  • both end faces of the fibers are sealed and polished, and the exit-side reflecting portion and the incident-side reflecting film are respectively provided on both end faces of the sealed and polished fibers.
  • the laser resistance of the incident side reflection film is improved.
  • the exit-side reflecting portion may be constituted by a reflecting film.
  • the emission-side reflection unit is specifically configured by the reflection film that reflects light of a predetermined wavelength with low reflectance.
  • the one fiber end surface is provided with a one-side reflecting film that reflects the light propagating through the core, and the other fiber end surface is reflected by the one-side reflecting film.
  • an exit-side reflecting portion that reflects a part of the light propagating through the core may be provided.
  • the one-side reflecting film provided on the one fiber end face generates the inside of the core by the excitation light incident on the first clad from the other fiber end face, and the inside of the core passes through the one fiber end face.
  • the light propagating toward the other side is reflected, and the part of the light that is reflected by the one-side reflecting film and propagates through the core end toward the other end of the fiber by the exit-side reflecting portion provided on the other fiber end face Is reflected and propagates again toward one end of the fiber.
  • the light propagating through the core of the double clad fiber is laser-oscillated by amplification and resonance between the exit-side reflecting portion and the one-side reflecting film, and is emitted from the core at the other fiber end.
  • the laser beam is emitted from the fiber end side with a large fiber diameter and the core diameter of the fiber end on the emission side is increased, the laser power density is lowered, and the laser resistance of the reflection part on the emission side is improved. .
  • both fiber end faces are sealed and polished
  • an exit-side reflecting portion and an incident-side reflecting film may be provided on both ends of the sealed and polished fiber.
  • the output side reflection part and the incident reflection are more than the case where the output side reflection part and the incident side reflection film are provided on both end faces of the fiber that are not sealed and polished, that is, each of the cut surfaces that are cut only. The laser resistance of the film will be improved.
  • the exit-side reflecting portion may be constituted by a reflecting film.
  • the emission-side reflection unit is specifically configured by the reflection film that reflects light of a predetermined wavelength with low reflectance.
  • the double clad fiber as described above is effective particularly in the fiber laser in the function and effect of the present invention.
  • each fiber end face is provided with a reflective portion and a reflective film, respectively, or a core, Since the diameters of the first and second claddings are increased from one fiber end to the other, the double-clad fiber with a highly heat-resistant air-clad structure is improved and higher than before.
  • An output fiber laser can be provided.
  • FIG. 1 is a cross-sectional view of a double-clad fiber 10 a according to Embodiment 1.
  • FIG. 2 is an observation photograph of a cross section of the double clad fiber 10 a according to the first embodiment.
  • FIG. 3 is a schematic configuration diagram of the fiber laser 30 a according to the first embodiment.
  • FIG. 4 is a first graph showing the spectral characteristics of the reflective film of the example.
  • FIG. 5 is a second graph showing the spectral characteristics of the reflective film of the example.
  • FIG. 6 is a schematic configuration diagram of a fiber laser 30 b according to the second embodiment.
  • FIG. 7 is a schematic configuration diagram of a fiber laser 30 c according to the third embodiment.
  • FIG. 8 is a schematic configuration diagram of a fiber laser 30 d according to the fourth embodiment.
  • FIG. 9 is a schematic configuration diagram of a fiber laser 30 e according to the fifth embodiment.
  • FIG. 10 is a schematic configuration diagram of a fiber laser 30 f according to another embodiment. BEST MODE FOR CARRYING OUT THE INVENTION
  • FIG. 1 to 5 show Embodiment 1 of a double clad fiber according to the present invention and a fiber laser including the same.
  • FIG. 1 is a cross-sectional view of the double-clad fiber 10a of this embodiment
  • FIG. 2 is an observation photograph of the cross-section of the double-clad fiber 10a.
  • FIG. 3 is a schematic configuration diagram of a fiber laser 30 a having a double clad fiber 10 a.
  • the double clad fiber 10a is provided around the core 1, the first clad 2 provided around the core 1, and around the first clad 2.
  • a support layer 4, a low refractive index resin layer 5 provided around the support layer 4, and a protective layer 6 provided around the low refractive index resin layer 5 are provided.
  • the low refractive index resin layer 5 and the protective layer 6 are omitted.
  • the double-clad fiber 10a has an output side reflecting portion that reflects part of the light propagating through the core 1 on one end face of the fiber (on the right side in FIG. 3).
  • a reflection film 1 2 is provided, and an incident-side reflection film 1 1 that reflects light propagating through the core 1 reflected by the emission-side reflection film 1 2 is reflected on the other fiber end face (left side in FIG. 3). Is provided.
  • the double-clad fiber 10a is composed of the core 1 and the first cladding from one fiber end (right side in FIG. 3) to the other fiber end (left side in FIG. 3). 2 is enlarged while maintaining a substantially similar shape. In other words, the diameter is reduced in a tapered shape from the incident-side reflecting film 11 toward the emitting-side reflecting film 12.
  • the core 1 is made of quartz, doped with a rare earth element such as ytterbium (Y b) as a light amplification component, and has a higher refractive index than the first cladding 2.
  • the diameter of the core 1 is, for example, about 150 ⁇ m at the incident side end face and about 60 m at the outgoing end face. Further, the numerical aperture (N A) of the core is about 0.06 at the end face on the incident side and the both end faces on the outgoing side.
  • the first cladding 2 is also called a pump guide and is made of quartz. Further, the diameter of the first cladding 2 is, for example, about 1500 ⁇ m at the end face on the incident side and about 600 ⁇ m at the end face on the output side. Further, the NA of the first cladding 2 is about 0.2 at the incident end face and about 0.5 at the exit end face.
  • Each of the second clads 3 has a plurality of pores 3 a extending along the core 1 and is made of quartz.
  • the refractive index of the second cladding 3 is a composite of the refractive index of air in the plurality of pores 3a and the refractive index of quartz in the portion other than the pores 3a. Is lower than the refractive index of quartz, that is, the refractive index of quartz.
  • the support layer 4 is made of quartz.
  • the diameter of the support layer 4 is, for example, about 2500 ⁇ m at the incident-side end face and about 100 00 ⁇ m at the exit-side end face.
  • the low refractive index resin layer 5 is made of, for example, silicon resin and has a lower refractive index than the support layer 4.
  • the protective layer 6 is made of, for example, ETFE (ethylene tetrafluoroethylene ene copolymer) resin.
  • Incident-side reflection film 11 is formed by laminating thin films such as Ta 2 0 5 and S i O 2 , for example, an optical element that reflects 99.8% of 1080 nm light. It is a thin film.
  • Outgoing side reflection film (outgoing side reflection part) 1 2 is configured by laminating thin films such as Ta 2 0 and S i 0 2 , for example, optical that reflects 5% of 10 80 nm light It is a thin film.
  • the double clad fiber 10 a having the above-described configuration is manufactured by heating and stretching a preform, drawing Q into a fiber shape, and then depositing thin films on both end faces of the fiber. Specifically, an example will be described below.
  • a cylindrical support tube made of quartz, a cylindrical clad rod made of quartz and doped with a predetermined amount of Yb along the central axis, and a plurality of cylindrical capillaries made of quartz Prepare a book.
  • the support pipe is filled with a plurality of capillaries, and the clad rod is arranged at the position of the center axis of the support pipe.
  • the formed preform is heated and drawn by drawing to form a fiber.
  • the fiber is formed in a tapered shape by adjusting the drawing speed.
  • the preform clad rod is placed in the double clad fiber 1 0 a 1 and the first clad 2 and the plurality of preforms of the double clad force double clad fiber 1 0 a in the second clad 3
  • the reformed support tube becomes the support layer 4 of the double-clad fiber 10 a.
  • each end surface of the fiber formed in a tapered shape is heated to end each fiber end surface.
  • each sealed fiber After sealing the pores 3a, the end face of each sealed fiber is polished with a grindstone or the like.
  • a plurality of thin films are deposited to form the incident side reflection film 11.
  • a plurality of thin films are vapor-deposited on the narrow end and polished end face of the tapered fiber by using an electron beam vapor deposition apparatus or an ion-assisted electron beam vapor deposition apparatus, and the output side reflection film 1 2 forms.
  • a low refractive index resin layer 5 is formed by applying and curing a silicon resin on the surface of the fiber support layer 4 on which the incident side reflection film 11 and the emission side reflection film 12 are formed
  • the protective layer 6 is formed by applying and curing EFTE resin on the surface of the low refractive index resin layer 5.
  • the double clad fiber 10a of this embodiment can be manufactured.
  • this fiber laser 30a is an L D (laser diode)
  • a lens 21 and a double clad fiber 10 a having the above-described configuration are arranged in order.
  • L D 20 is an excitation light source that outputs an excitation light that combines two wavelengths of 9 15 nm and 9 40 nm, for example.
  • the lens 21 has a NA of about 0.2, and condenses the excitation light 26 from the L D 20 to, for example, a spot diameter of 15 500 ⁇ m.
  • the pumping light 26 from the LD 20 enters the first cladding 2 of the double-clad fiber 10 a via the lens 21, and the incident excitation light 26 becomes the first 1 Propagating in the region surrounded by the second cladding 3 while repeating reflection at the interface between the cladding 2 and the second cladding 3, and when the excitation light 26 passes through the core 1, the rare earth elements in the core 1 are Activates to generate spontaneously emitted light. Then, the spontaneous emission light generated in the core 1 propagates through the core 1 and reaches the output-side reflection film 12.
  • the spontaneously emitted light the light having the wavelength (approximately 1800 nm) included in the reflection wavelength band of the outgoing-side reflection film 12 is reflected and propagates inside the core 1 again. become. Further, the light reflected by the exit-side reflection film 12 and propagated inside the core 1 is reflected by the entrance-side reflection film 11 and propagates inside the core 1 again.
  • the fiber laser 30 a since the incident-side reflection film 11 and the emission-side reflection film 12 2 form a resonator, resonance occurs between the incidence-side reflection film 11 and the emission-side reflection film 12. The laser is oscillated by repeated stimulated emission, and the laser 27 is taken out.
  • the diameters of the core 1, the first clad 2 and the second clad 3 are equal to one fiber end (see FIG.
  • the core 1 and the first cladding 2 expand in diameter while maintaining the similar shape from the other fiber end (left side in Fig. 3) to the other end of the fiber (in other words, the incidence of excitation light 26) From the side (left side in Fig. 3) in a taper shape along the length direction, and the second cladding 3 has an air cladding structure including a plurality of pores 3a.
  • the numerical aperture increases continuously along the length from the incident side of excitation light 26 (left side in Fig. 3). For this reason, the leakage of the excitation light 26 transmitted through the first cladding 2 to the outside can be suppressed.
  • the laser resistance of the incident side reflection film 11 provided on the left side of 3 can be improved.
  • exit-side reflecting film 12 and the incident-side reflecting film 11 are directly provided on the end face of each fiber, they are coupled with optical elements such as the lens 21 and LD 26 that constitute the fiber laser 30 a. The optical adjustment can be facilitated.
  • the diameter of the core 1 is tapered from the incident side of the excitation light 26 (the left side in Fig. 3) along the length direction, the diameter of the light propagating through the core 1 is high.
  • the next-mode light leaks outside while propagating through the core, and the low-order mode light resonates mainly between the output-side reflection film 1 2 and the incident-side reflection film 1 1. Can improve the beam quality of the laser.
  • the pump light 26 is output. Coupling with LD 20 can be facilitated.
  • the excitation light 26 propagated through the first cladding 2 Suppression of leakage, improvement of laser resistance of the exit side reflection film 1 2 and incidence side reflection film 1 1, easy optical adjustment when coupled with LD 2 0, etc., and oscillation laser 2 7 beam Since the quality can be improved, it is possible to improve the heat-resistant double-clad fiber with an air-clad structure and provide a fiber laser with higher output than before.
  • the difference between the fiber laser 30 a of this embodiment and the conventional fiber laser is clarified.
  • an FBG Fiber Bragg Grating
  • the core is shielded by the pores that make up the air-clad, so it is difficult to write FBG directly into the fiber core.
  • a resonator is constituted by the entrance-side reflection film 11 and the exit-side reflection film 12 formed on both end faces of the fiber of the double clad fiber 10 a. Therefore, the resonator can be easily formed in the fiber, the adjustment of the shaft is unnecessary, and the end face destruction as described above can be suppressed.
  • the output side reflection film 12 is exemplified as the output side reflection part. However, in the present invention, the output side reflection film 12 is omitted, and the output side reflection part is configured by Fresnel reflection of the fiber end face. You may let them.
  • a double-clad fiber 10 a was produced by the same method as in the above embodiment, and a fiber laser 30 a was configured.
  • the incident side reflection film 11 was formed with the configurations shown in Tables 1 to 3 below. / ssso 0 /: 02TI> d / ⁇ 6 ⁇ 0 ⁇ O OSAV ⁇ ⁇
  • Table 1 (3 Where, Table 1, using an electron beam evaporator, a condition when forming the reflection film by alternately 3 0 layers are stacked T a 2 O 5 thin film and S I_ ⁇ 2 thin film, Table 2 shows the conditions when a reflective film is formed by alternately stacking 30 layers of Ta 2 O s thin films and Si 0 2 thin films using an ion-assisted electron beam evaporation apparatus. using Ion'ashisu preparative electron beam deposition apparatus, a condition when forming the reflective film alternately 3 0 layers are stacked T i ⁇ 2 thin film and S I_ ⁇ 2 thin film.
  • FIG. 4 is a graph showing the spectral characteristics of each reflective film formed under the conditions shown in Tables 1 to 3.
  • the solid curve in the graph is the spectral characteristic of the reflective film according to Table 1
  • the dashed curve in the graph is the spectral characteristic of the reflective film according to Table 2
  • the dashed-dotted curve in the graph is according to Table 3. It is the spectral characteristic of a reflecting film.
  • the reflective film having the structure shown in Table 1 was excellent in laser resistance, although the reflectance was lower than that of the reflective film having the structure shown in Table 2 and Table 3.
  • the exit-side reflection film 12 was formed with the configuration shown in Tables 4 to 7 below.
  • Table 4 shows the conditions when a reflective film is formed by alternately stacking 4 layers of Ta 2 0 5 thin films and S i 0 2 thin films using an electron beam evaporation apparatus.
  • Table 6 shows the conditions when a reflective film is formed by alternately stacking 4 layers of Ta 2 O s thin films and S i 0 2 thin films using an ion assisted electron beam evaporation system.
  • FIG. 5 is a graph showing the spectral characteristics of each reflective film formed under the conditions shown in Tables 4-7.
  • the solid curve in the graph is the spectral characteristic of the reflective film according to Table 4
  • the dashed curve in the graph is the spectral characteristic of the reflective film according to Table 5
  • the dashed-dotted curve in the graph is according to Table 6. This is the spectral characteristic of the reflective film.
  • the double-dashed line in the graph is the spectral characteristic of the reflective film according to Table 7.
  • each of the reflective films having the configurations shown in Table 4 to Table 7 has no significant difference in reflectance as shown in FIG. It was superior in laser resistance to the reflective film with the structure shown in Fig. 6. Further, the reflective film having the configuration shown in Table 7 showed the same laser resistance as the reflective film having the configuration shown in Table 4.
  • a double-sided reflection film 11 having the structure shown in Table 1 is provided on the thick end face of the fiber, and an output-side reflection film 12 having the structure shown in Table 4 is provided on the thin end face of the fiber.
  • the cladding fiber 10 a had an absorption coefficient (loss) of excitation light of 11.0 dBZm at 9 15 nm.
  • a 2 kW laser 27 was output from the fiber laser 30 a having a double clad fiber 10 a having a total length of 3 O m and an output 3 3 ⁇ 4: ⁇ 0 20.
  • FIG. 6 shows a fiber laser including the double clad fiber 10 b according to the present embodiment.
  • FIG. 3 is a schematic configuration diagram of 30 b.
  • the same components as those in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.
  • this fiber laser 30 b includes L D 20 and an incident side lens unit.
  • the double-clad fiber 10b is substantially the same as the configuration of the first double-clad fiber 10a of the first embodiment except that no reflection film is provided on both end faces of the fiber.
  • the incident-side lens portion 21c includes a first lens 21a and a second lens 2lb disposed opposite to each other, and an incident-side reflecting portion 22 provided between them, and LD 20 It is an optical element for condensing the excitation light 26 from the light to a predetermined spot diameter.
  • the emission side lens portion 23 c is an optical element that includes a lens 23 a and an emission side reflection portion 23 b that are arranged to face each other, and emits a laser 27.
  • the incident-side reflection part 22 and the emission-side reflection part 23 b are, for example, an optical thin film that reflects 109.8 nm light at 99.8 ° / 0 , and 5% reflection at 1080 nm light.
  • Each of the optical thin films functions as an external resonator of the double clad fiber 10b.
  • each diameter of the core 1, the first cladding 2 and the second cladding 3 is changed from one fiber end (right side in FIG. 6) to the other fiber end (in FIG. 6).
  • the core 1 and the first cladding 2 are enlarged in diameter while maintaining a similar shape toward the left), in other words, from the incident side of the excitation light 26 (left side in FIG.
  • the second cladding 3 has an air cladding structure including a plurality of pores 3 a, so that the numerical aperture of the first cladding 2 is the incident side of the excitation light 26 ( It rises continuously along the length direction from the left side in Fig. 6. Therefore, it is possible to suppress the leakage of the excitation light 26 propagating through the first cladding 2 to the outside.
  • an output-side reflecting portion 2 3 b for reflecting a part of the light propagating through the core 1 is provided at one fiber end (right side in FIG. 6), and the other fiber end (left side in FIG. 6).
  • the other end of the fiber (left side in Fig. 6) is incident on the first cladding 2 by the pumping light 2 6 and is generated inside the core 1 and the inside of the core 1 passes through the end of one fiber
  • a part of the light propagating toward the right side is reflected by the incident side reflection part 2 2 and reflected by the emission side reflection part 2 3 b, and the other fiber end (left side in FIG. 6). ),
  • the light propagating in the core 1 is reflected and propagates again toward one fiber end (right side in Fig. 6).
  • the fiber laser 30 b the light propagating through the core 1 of the double-clad fiber 10 b is laser-oscillated by amplification and resonance between the exit-side reflecting portion 23 b and the incident-side reflecting portion 22.
  • the light is emitted from the core 1 at one fiber end (right side in FIG. 6).
  • the diameter of the core 1 is tapered from the incident side of the excitation light 26 (left side in FIG. 6) along the length direction, the diameter of the light propagating through the core 1 is high.
  • the light of the next mode leaks to the outside while propagating in the core, and the light of the lower order mode mainly resonates between the output side reflection part 2 3 b and the incident side reflection part 2 2,
  • the beam quality of the oscillated laser 27 can be improved.
  • the diameter of the other fiber end (left side in Fig. 6) where the pump light 26 enters is larger, the diameter of the other fiber end (right side in Fig. 6) becomes larger. Coupling with D 20 and the incident side lens portion 21 c can be facilitated.
  • FIG. 7 is a schematic configuration diagram of the fiber laser 30 c of this embodiment.
  • the Q switch 24 and the low reflection mirror 23b are arranged in this order, and the other configuration is substantially the same as that of the fiber laser 30a.
  • the Q switch 2 in addition to the effect of the first embodiment, the Q switch 2
  • FIG. 8 is a schematic configuration diagram of a fiber laser 30 d provided with the double clad fiber 10 d of the present embodiment.
  • a grating fiber 10 G is fused to one end face of the fiber, and the other configuration is substantially the same as the fiber laser 30 a.
  • F B G 14 that functions as the emission-side reflecting portion is formed in the core at the center of the fiber.
  • this fiber laser 30 d it is possible to prepare a plurality of fiber lasers 30 b, bundle the grating fibers 10 G at their respective ends, and perform fiber force coupling with other multimode fibers, for example, A high-power laser can be emitted from the end of the multimode fiber.
  • FIG. 9 is a schematic configuration diagram of a fiber laser 30 e provided with the double clad fino 10 e of the present embodiment.
  • the fiber laser 30 e has an LD 20, a first lens 21 a, a dichroic mirror 25, a second lens 21 b, and a double clad fibre 10 e in order. It is an optical device.
  • the dichroic mirror 25 is configured to transmit 10 0 80 nm light and reflect 9 0 0 to 100 0 nm light.
  • Double-clad fiber 10 e is provided with one side reflection film 13 on one fiber end face (right side in Fig. 9), and on the other fiber end face (left side in Fig. 9). Is substantially the same as the configuration of the double-clad fiber 10 a of Embodiment 1.
  • the one-side reflecting film 13 is formed by laminating thin films such as Ta 2 0 5 and S i O 2 , for example, an optical that reflects 99.8% of 10 8 0 11 111 light. It is a thin film.
  • the exit-side reflection film 12 a is formed by laminating thin films such as Ta 2 0 5 and Si 0 2, and is, for example, an optical thin film that reflects 5% of 10 80 nm light.
  • the pumping light 26 from the LD 20 force is transmitted through the first lens 21 a, the dichroic mirror 25 and the second lens 21 b to the double-cladding fiber 10 e.
  • the incident excitation light 26 enters the first cladding 2 and propagates in the region surrounded by the second cladding 3 while being reflected at the interface between the first cladding 2 and the second cladding 3.
  • the excitation light 26 passes through the core 1, the rare earth element in the core 1 is activated to generate spontaneous emission light. Then, the spontaneous emission light generated in the core 1 propagates in the core 1 and reaches the one-side reflecting film 13.
  • the spontaneously emitted light the light having a wavelength (about 10 80 nm) included in the reflection wavelength band of the one-side reflective film 13 is reflected and propagates inside the core 1 again. become. Furthermore, a part of the light reflected by the one-side reflecting film 13 and propagated inside the core 1 is reflected by the emitting-side reflecting film 1 2 a and propagates inside the core 1 again. Become.
  • the fiber laser 30 e since the one-side reflecting film 13 and the emitting-side reflecting film 12 2 a form a resonator, resonance occurs between the one-side reflecting film 13 and the emitting-side reflecting film 1 2 a. The laser oscillation occurs due to repeated stimulated emission, and the laser 27 is reflected on the output side reflection film 1 2 a. And the second lens 21b and the dichroic mirror 25.
  • the laser 27 emits from the fiber end side with a large fiber diameter, and the diameter of the core 1 at the fiber end on the output side is the diameter of the core 1 on the output side in each of the above embodiments. Therefore, it is possible to improve the laser resistance of the exit side reflection film 12 a when the power density of the laser is lowered.
  • a fiber laser including a double-clad fiber formed in a tapered shape has been exemplified.
  • the present invention is a cylindrical double-clad fiber with a constant fiber diameter. It can be applied to fiber laser 30 f with f. Industrial applicability
  • the present invention can easily oscillate a high-power laser, it is useful for various laser processing such as welding.

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Lasers (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

Abstract

La présente invention concerne une fibre à gaine double (10a) qui comprend : une âme (1) pourvue d'un composant d'amplification optique dopé ; une première gaine (2) servant à couvrir l'âme (1) ; et une seconde gaine (3) possédant une pluralité de fins orifices (3a) s'étendant le long de l'âme (1) de manière à couvrir la première gaine (2). Un film réfléchissant côté émission (12) qui réfléchit une partie de la lumière se propageant dans l'âme (1) est disposé sur une face terminale de la fibre. Un film réfléchissant côté incident (11) qui réfléchit la lumière renvoyée par le film réfléchissant côté émission (12) et se propageant dans l'âme (1) est disposé sur l'autre face terminale de la fibre. L'âme (1), la première (2) et la seconde gaine (3) possèdent des diamètres allant croissant d'une face terminale à l'autre de la fibre.
PCT/JP2007/055164 2006-03-17 2007-03-08 Fibre a double gaine et laser a fibre l'utilisant WO2007108391A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2006-074135 2006-03-17
JP2006074135A JP2007250951A (ja) 2006-03-17 2006-03-17 ダブルクラッドファイバ及びそれを備えたファイバレーザ

Publications (1)

Publication Number Publication Date
WO2007108391A1 true WO2007108391A1 (fr) 2007-09-27

Family

ID=38522421

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2007/055164 WO2007108391A1 (fr) 2006-03-17 2007-03-08 Fibre a double gaine et laser a fibre l'utilisant

Country Status (2)

Country Link
JP (1) JP2007250951A (fr)
WO (1) WO2007108391A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013160770A3 (fr) * 2012-04-27 2014-02-27 Biolitec Pharma Marketing Ltd. Système de laser à fibre pour applications médicales

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5266701B2 (ja) * 2007-09-27 2013-08-21 カシオ計算機株式会社 撮像装置、被写体分離方法、およびプログラム
WO2009043964A1 (fr) * 2007-10-03 2009-04-09 Optoelectronics Research Centre, Tampere University Of Technology Fibre optique active et son procédé de fabrication
JP2009212184A (ja) * 2008-03-03 2009-09-17 Mitsubishi Cable Ind Ltd ファイバレーザ装置
KR20110002008A (ko) * 2008-04-03 2011-01-06 아사히 가라스 가부시키가이샤 와이어 그리드형 편광자 및 그 제조 방법
JP5178328B2 (ja) * 2008-06-05 2013-04-10 三菱電線工業株式会社 光ファイバ
JP2010205926A (ja) * 2009-03-03 2010-09-16 Mitsubishi Cable Ind Ltd 光ファイバ装置およびその製造方法
JP2012238781A (ja) * 2011-05-13 2012-12-06 Mitsubishi Electric Corp Ｙｂ添加ガラスファイバを用いるファイバレーザ発振器およびファイバレーザ増幅器
EP2662939B1 (fr) 2012-05-08 2020-08-19 Fianium Limited Systèmes de laser présentant des éléments coniques
US11175449B2 (en) * 2019-01-02 2021-11-16 Lumentum Operations Llc Optical fiber with variable absorption
US11808970B2 (en) * 2019-01-02 2023-11-07 Lumentum Operations Llc Optical fiber with variable absorption

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06283798A (ja) * 1993-03-30 1994-10-07 Nippon Telegr & Teleph Corp <Ntt> ファイバレーザ及び光ファイバ増幅器
WO2004112207A1 (fr) * 2003-06-12 2004-12-23 Southampton Photonics Ltd. Appareil optique comprenant un convertisseur de luminosite et permettant de produire un rayonnement optique
JP2005079197A (ja) * 2003-08-28 2005-03-24 Fujikura Ltd 希土類元素添加ファイバ、光ファイバレーザ
JP2005121902A (ja) * 2003-10-16 2005-05-12 Sony Corp 光ファイバの製造方法および光ファイバ装置の製造方法
JP2005150229A (ja) * 2003-11-12 2005-06-09 Fujikura Ltd 光ファイバレーザ
JP2005159142A (ja) * 2003-11-27 2005-06-16 Fujikura Ltd Ｑスイッチパルス光ファイバレーザ装置及びエルビウム添加光ファイバ

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06283798A (ja) * 1993-03-30 1994-10-07 Nippon Telegr & Teleph Corp <Ntt> ファイバレーザ及び光ファイバ増幅器
WO2004112207A1 (fr) * 2003-06-12 2004-12-23 Southampton Photonics Ltd. Appareil optique comprenant un convertisseur de luminosite et permettant de produire un rayonnement optique
JP2005079197A (ja) * 2003-08-28 2005-03-24 Fujikura Ltd 希土類元素添加ファイバ、光ファイバレーザ
JP2005121902A (ja) * 2003-10-16 2005-05-12 Sony Corp 光ファイバの製造方法および光ファイバ装置の製造方法
JP2005150229A (ja) * 2003-11-12 2005-06-09 Fujikura Ltd 光ファイバレーザ
JP2005159142A (ja) * 2003-11-27 2005-06-16 Fujikura Ltd Ｑスイッチパルス光ファイバレーザ装置及びエルビウム添加光ファイバ

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013160770A3 (fr) * 2012-04-27 2014-02-27 Biolitec Pharma Marketing Ltd. Système de laser à fibre pour applications médicales

Also Published As

Publication number Publication date
JP2007250951A (ja) 2007-09-27

Similar Documents

Publication Publication Date Title
WO2007108391A1 (fr) Fibre a double gaine et laser a fibre l&#39;utilisant
US7813603B2 (en) Optical coupler devices, methods of their production and use
US8564877B2 (en) Photonic bandgap fiber and fiber amplifier
US20050117860A1 (en) Microstructured optical fibre with cladding recess, a method of its production, and apparatus comprising same
JP5688565B2 (ja) ファイバレーザ装置と光増幅方法
JP2002270928A (ja) 光励起方法、光増幅装置及びファイバレーザ装置、並びに光ファイバ
WO2018066470A1 (fr) Fibre optique et laser à fibres
JP2002111101A (ja) レーザ光源装置
US8781274B2 (en) Optical amplifier and resonator
WO2018066148A1 (fr) Fibre optique et laser à fibre
JP2007214431A (ja) 光ファイバレーザ
JP2012209510A (ja) 光ファイバレーザ光源
JPH05251796A (ja) １．３μｍ帯光増幅器
JP5281952B2 (ja) レーザ装置
WO2010149163A1 (fr) Dispositif de coupleur optique
WO2005069453A1 (fr) Fibre optique et procede de fabrication
JP2013161875A (ja) 光学部品、及び、これを用いた光ファイバ増幅器、及び、ファイバレーザ装置
JP2008226885A (ja) 希土類添加フォトニックバンドギャップファイバ及び光増幅器
WO2006098313A1 (fr) Amplificateur optique et dispositif laser
JP6636562B2 (ja) ガラスブロック、光ファイバ終端構造、レーザ装置、及びレーザシステム
JP2019220541A (ja) 光ファイバレーザ装置
JP2015179761A (ja) ファイバレーザ装置
JP2007071950A (ja) ダブルクラッドホーリーファイバ、ファイバアンプ及びファイバレーザ
JP2005251992A (ja) 光ファイバレーザ
JP2009212184A (ja) ファイバレーザ装置

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: 07715336

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: 07715336

Country of ref document: EP

Kind code of ref document: A1