JP2014163955A - Leakage light removal component, combiner, optical amplifier, and a fiber laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leakage light removal component capable of improving the life of an optical fiber, a combiner, an optical amplifier, and a fiber laser device.SOLUTION: A light leakage removal component 3 includes an optical fiber 50 including a core 51 and a clad 52 having a lower refractive index than the core 51, and a leakage light processing member 60 provided on the optical fiber 50. The leakage light processing member 60 comprises a light-transmissive resin layer 61 covering an outer peripheral surface of the clad 52 of the optical fiber 50, a light-transmissive heat insulation layer 62 covering at least a part of an outer peripheral surface of the resin layer 61, and a metal layer 63 surrounding an outer peripheral surface of the heat insulation layer 62. Refractive indexes of the heat insulation layer 62 and the resin layer 61 are higher than that of the clad 52 of the optical fiber 50, and a thermal conductivity of the heat insulation layer 62 is lower than that of the metal layer 63, and a glass transition temperature of the heat insulation layer 62 is higher than that of the resin layer 61.

Description

  The present invention relates to a leakage light removing component, an optical amplifier, and a fiber laser device.

  When the amplification optical fiber and the delivery fiber are fusion-spliced, the input to the core of the delivery fiber is caused by misalignment between the core of the amplification optical fiber and the core of the delivery fiber, mode field mismatch, etc. Some of the light that leaks may leak into the cladding.

  The following Patent Document 1 has been proposed as a structure for removing such leakage light. In Patent Document 1, a leakage light removing unit that covers the second optical fiber is provided in the vicinity of the fused portion between the end surface of the output end of the first optical fiber and the end surface of the incident end of the second optical fiber. ing. The refractive index of the leakage light removing unit is set to be equal to or higher than the refractive index of the coating layer of the second optical fiber. And the metal case which accommodates a leakage light removal part is provided so that a leakage light removal part and a wall surface may contact. Moreover, in this patent document 1, it is described by setting it as such a structure that the temperature rise of an optical fiber can be suppressed by leak light.

JP2011-186399

  However, in the above-mentioned patent document, heat generated in the metal case may be conducted to the optical fiber through the leakage light removing unit, and the optical fiber may be deteriorated by the heat. In particular, in recent years, there is an increasing demand for higher output in the amplification optical fiber, and thus the above problem is considered to be actualized.

  Accordingly, an object of the present invention is to provide a leakage light removing component, a combiner, an optical amplifier, and a fiber laser device that can improve the lifetime of an optical fiber.

  In order to solve the above problems, a leakage light removing component of the present invention includes a core, an optical fiber having a clad having a refractive index lower than that of the core, and a leakage light processing member provided in the optical fiber, The light processing member surrounds the outer peripheral surface of the heat insulating layer, the light transmitting resin layer covering the outer peripheral surface of the clad, the light transmitting heat insulating layer covering at least a part of the outer peripheral surface of the resin layer. A refractive index of the heat insulation layer and the resin layer is larger than a refractive index of the clad in the optical fiber, and a thermal conductivity of the thermal insulation layer is smaller than a thermal conductivity of the metal layer. The glass transition temperature of the heat insulation layer is higher than the glass transition temperature of the resin layer.

In this leakage light removing component, the refractive index of the light-transmitting resin layer covering the outer peripheral surface of the clad in the optical fiber and the refraction of the light-transmitting heat insulating layer covering at least a part of the outer peripheral surface of the resin layer. The index is made larger than the refractive index of the cladding. For this reason, the light leaking into the clad propagates while being refracted from the resin layer toward the heat insulating layer, reaches the metal layer surrounding the outer peripheral surface of the heat insulating layer, and is converted into heat by the metal layer. As a result, it is possible to greatly suppress the deterioration of the coating layer of the optical fiber due to leakage light.
Moreover, the heat conductivity of a heat insulation layer is smaller than the heat conductivity of a metal layer, and the glass transition temperature of the said heat insulation layer is made higher than the glass transition temperature of a resin layer. For this reason, conduction of heat generated in the metal layer with respect to the resin layer can be suppressed by the heat insulating layer whose degree of modification by heat is smaller than that of the resin layer. Accordingly, it is possible to reduce the deterioration of the resin layer due to the heat generated in the metal layer and to reduce the deterioration of the heat insulating layer itself in contact with the metal layer. As a result, the heat conduction to the optical fiber can be significantly suppressed as compared with the case where the optical fiber and the metal layer are not composed of the resin layer and the heat insulating layer, but only the resin layer. .
As described above, the leakage light processing member provided in the optical fiber converts the leakage light into heat, thereby suppressing the deterioration of the coating layer of the optical fiber due to the leakage light and conducting the heat to the optical fiber. Can be suppressed. Thus, a leakage light removing component that can improve the life of the optical fiber is realized.

  Moreover, it is preferable that the thickness of the said heat insulation layer is larger than the thickness of the said resin layer.

  When it does in this way, a resin layer can be kept away from the heat | fever which arose in the metal layer with the heat insulation layer whose modification | denaturation degree is smaller than the said resin layer. Therefore, deterioration of the resin layer due to heat generated in the metal layer can be further reduced.

  The refractive index of the heat insulating layer is preferably larger than the refractive index of the resin layer.

  When it does in this way, the leak light which leaks to a clad can be propagated to a metal layer irrespective of the incident angle of the leak light with respect to a heat insulation layer. Therefore, the leaked light can be converted into heat more efficiently.

  Moreover, it is preferable that the boundary surface of the said heat insulation layer and the said resin layer shall be uneven | corrugated shape.

  In this case, since the amount of leakage light per unit area of the optical fiber covered with the resin layer can be increased, the leakage light propagated to the resin layer is efficiently converted into heat by the metal layer. be able to.

  The heat insulating layer can be made of an inorganic material.

  The combiner according to the present invention includes a plurality of pumping optical fibers for propagating pumping light, an optical fiber disposed at a subsequent stage of the plurality of pumping optical fibers, a core in the plurality of pumping optical fibers, and a core in the optical fiber. And a light leakage processing member provided in the optical fiber, and the light input member has a tapered portion whose diameter decreases from the input side toward the output side, and the light leakage processing The member includes a light transmissive resin layer covering the outer peripheral surface of the clad, a light transmissive heat insulating layer covering at least a part of the outer peripheral surface of the resin layer, and a metal layer surrounding the outer peripheral surface of the heat insulating layer. The refractive index of the heat insulating layer and the resin layer is larger than the refractive index of the cladding in the optical fiber, the thermal conductivity of the heat insulating layer is smaller than the thermal conductivity of the metal layer, Refusal The glass transition temperature of the layer is characterized by higher than the glass transition temperature of the resin layer.

In such a combiner, since the optical input member has a tapered portion whose diameter decreases from the input side to the output side, the NA (Numerical Aperture) of the light exceeds the allowable NA in the optical fiber at the subsequent stage. The tendency for light to leak from the core of the latter optical fiber to the cladding increases.
However, in this combiner, as described above, the leakage light processing member provided in the subsequent optical fiber converts the leakage light into heat, so that the deterioration of the coating layer of the optical fiber due to the leakage light is suppressed, Heat conduction to the optical fiber can be suppressed. Thus, a combiner that can improve the lifetime of the optical fiber is realized.

  An optical amplifier according to the present invention includes a core, an optical fiber for amplification having an inner cladding and an outer cladding whose refractive index is lower than that of the core, and an optical input member for inputting pumping light to one end of the inner cladding of the optical fiber for amplification. A leakage light processing member provided on the amplification optical fiber, the leakage light processing member comprising: a light-transmitting resin layer that covers an outer peripheral surface of an outer cladding of the amplification optical fiber; and A light-transmitting heat insulating layer covering at least a part of the outer peripheral surface, and a metal layer surrounding the outer peripheral surface of the heat insulating layer, and the refractive indexes of the heat insulating layer and the resin layer in the amplification optical fiber It is larger than the refractive index of the outer cladding, the thermal conductivity of the thermal insulation layer is smaller than the thermal conductivity of the metal layer, and the glass transition temperature of the thermal insulation layer is the glass transition temperature of the resin layer. Remote, characterized in that high.

  The fiber laser device of the present invention includes a core, an amplification optical fiber having an inner cladding and an outer cladding whose refractive index is lower than that of the core, a seed light source and an excitation light source, and seed light emitted from the seed light source. A light input member for inputting to one end of the core of the amplification optical fiber and inputting the excitation light emitted from the excitation light source to one end of the inner cladding of the amplification optical fiber, and provided in the amplification optical fiber A leakage light processing member, and the leakage light processing member covers at least a part of the outer peripheral surface of the resin layer and a light-transmitting resin layer that covers the outer peripheral surface of the outer cladding of the amplification optical fiber. A heat-transmitting heat-insulating layer and a metal layer surrounding an outer peripheral surface of the heat-insulating layer, and the refractive index of the heat-insulating layer and the resin layer is in the amplification optical fiber. The thermal conductivity of the heat insulation layer is smaller than the thermal conductivity of the metal layer, and the glass transition temperature of the heat insulation layer is higher than the glass transition temperature of the resin layer. It is characterized by.

  The fiber laser device of the present invention includes a core, an optical fiber for amplification having an inner cladding and an outer cladding whose refractive index is lower than that of the core, a pumping light source, and pumping light emitted from the pumping light source. A light input member that is input to one end of the inner cladding of the optical fiber, a pair of mirrors disposed at a predetermined distance from the amplification optical fiber, and a leakage light processing member provided in the amplification optical fiber, The leakage light processing member includes a light transmissive resin layer covering an outer peripheral surface of an outer clad in the amplification optical fiber, a light transmissive heat insulating layer covering at least a part of the outer peripheral surface of the resin layer, A metal layer surrounding the outer peripheral surface of the heat insulating layer, and the refractive index of the heat insulating layer and the resin layer is larger than the refractive index of the outer cladding in the amplification optical fiber. , Thermal conductivity of the heat insulation layer, the lower than the thermal conductivity of the metal layer, the glass transition temperature of the heat insulation layer, characterized in that above the glass transition temperature of the resin layer.

  In the optical amplifier or the fiber laser device, the optical fiber and the leakage light processing member in the leakage light removing component are used as a part of the constituent elements. That is, an amplification optical fiber is applied as the optical fiber of the leakage light removing component, and the leakage light processing member is provided on the amplification optical fiber. Even in such a case, the leakage light processing member provided in the amplification optical fiber converts the leakage light into heat in the same manner as the leakage light removing component, so that the coating layer caused by the leakage light can be removed. While suppressing deterioration, the heat conduction from the leakage light processing member with respect to the optical fiber for amplification can be suppressed. Thus, an optical amplifier and a fiber laser device that can improve the lifetime of the optical fiber are realized.

  As described above, according to the present invention, it is possible to provide a leakage light removing component, a combiner, an optical amplifier, and a fiber laser device that can improve the lifetime of an optical fiber.

It is a figure which shows the fiber laser apparatus in 1st Embodiment. It is a figure which shows the mode of the structure of a cross section perpendicular | vertical to the length direction of the optical fiber for amplification. It is a figure which shows the mode of the structure of a cross section perpendicular | vertical to the length direction of a delivery fiber. It is a figure which shows the mode of a cross section perpendicular | vertical to the length direction of a leak light processing member. It is a figure which shows the fiber laser apparatus in 2nd Embodiment. It is a figure which shows the fiber laser apparatus in 3rd Embodiment. It is a figure which shows the structure of a light input member.

(1) First Embodiment A preferred first embodiment of the present invention will be described in detail with reference to the drawings.
<Configuration of fiber laser device>
FIG. 1 is a diagram showing a fiber laser device 1 according to the first embodiment. As shown in FIG. 1, the fiber laser device 1 is an MO-PA (Master Oscillator Power Amplifier) type fiber laser device, and includes a seed light source 10, an excitation light source 20, an optical amplifier 2, and a leakage light removing component 3. As a component. The optical amplifier 2 includes an amplification optical fiber 30 and an optical input member 40 as main components, and the leak light removal component 3 includes a delivery fiber 50 and a leak light processing member 60 as main components.

  The seed light source 10 is a member that outputs seed light, and is, for example, a laser light source composed of a laser diode, a Fabry-Perot type, or a fiber ring type fiber laser. A seed optical fiber 15 composed of a core and a clad covering the core is connected to the seed light source 10. An example of the seed optical fiber 15 is a single mode fiber.

  The excitation light source 20 is a member that outputs excitation light and includes, for example, a plurality of laser diodes 21. A pumping optical fiber 22 is connected to these laser diodes 21.

  FIG. 2 is a diagram illustrating a cross-sectional structure perpendicular to the length direction of the amplification optical fiber 30. As shown in FIG. 2, the amplification optical fiber 30 includes a core 31, an inner cladding 32 that covers the core 31, an outer cladding 33 that covers the inner cladding 32, and a coating layer 34 that covers the outer cladding 33. Composed. The refractive index of the core 31 is higher than the refractive index of the inner cladding 32, and the refractive index of the inner cladding 32 is higher than the refractive index of the outer cladding 33.

  Examples of the material constituting the core 31 include quartz to which an element such as germanium for increasing the refractive index and an active element excited by excitation light output from the excitation light source 20 are added. Examples of the active element include rare earth elements such as ytterbium (Yb), thulium (Tm), cerium (Ce), neodymium (Nd), europium (Eu), and erbium (Er). In addition to rare earth elements, bismuth (Bi) and the like can be given. An example of the material constituting the inner clad 32 is pure quartz to which no dopant is added, and an example of the material constituting the outer clad 33 is an ultraviolet curable resin. Moreover, as a material which comprises the coating layer 34, the ultraviolet curing resin different from resin which comprises the outer side clad 33 is mentioned, for example.

  The light input member 40 inputs the seed light emitted from the seed light source 10 to one end of the core 31 in the amplification optical fiber 30 and transmits the excitation light emitted from the excitation light source 20 to the inner cladding 32 in the amplification optical fiber 30. This is a member that is input to one end of the.

  Specifically, the light input member 40 emits from the seed light source 10 through the seed optical fiber 15 by optically coupling the end surfaces of the core of the seed optical fiber 15 and the core 31 of the amplification optical fiber 30. The seed light is input to one end of the core 31 in the amplification optical fiber 30.

  The optical input member 40 is emitted from the excitation light source 20 through the excitation optical fiber 22 by optically coupling the end surfaces of the core of the excitation optical fiber 22 and the inner cladding 32 of the amplification optical fiber 30. Pumping light is input to one end of the inner cladding 32 of the amplification optical fiber 30.

  The delivery fiber 50 is an optical fiber that transmits the light amplified by the amplification optical fiber 30 to the subsequent stage. FIG. 3 is a view showing a state of a cross section perpendicular to the length direction of the delivery fiber 50. As shown in FIG. 3, the delivery fiber 50 includes a core 51, a cladding 52 that covers the core 51, and a coating layer 53 that covers the cladding 52.

  The refractive index of the core 51 is set higher than the refractive index of the clad 52. The diameter of the core 51 is, for example, approximately the same as the diameter of the core 31 in the amplification optical fiber 30, and the outer diameter of the cladding 52 is, for example, approximately the same as the outer diameter of the inner cladding 32 in the amplification optical fiber 30.

  Examples of the material constituting the core 51 include quartz to which an element such as germanium for increasing the refractive index is added. Examples of the material constituting the clad 52 include pure quartz to which no dopant is added. Can be mentioned. Moreover, as a material which comprises the coating layer 53, ultraviolet curable resin is mentioned, for example.

  FIG. 4 is a diagram illustrating a state of a connection portion between the amplification optical fiber 30 and the delivery fiber 50. Specifically, FIG. 4A shows a cross-sectional view of the amplification optical fiber 30, the delivery fiber 50, and the leakage light processing member 60 that are perpendicular to the length direction of the delivery fiber 50, and FIG. The mode of the cross section of the VV line in (A) of FIG. 4 is shown.

  As shown in FIG. 4A, one end surface of the core 51 in the delivery fiber 50 is fusion-bonded to one end surface on the output end side of the core 31 in the amplification optical fiber 30. Further, one end face of the clad 52 in the delivery fiber 50 is fusion-bonded to one end face on the output end side of the inner clad 32 in the amplification optical fiber 30. Note that the one end surface on the output side of the amplification optical fiber 30 is the one end surface on the opposite side to the one end to which seed light and excitation light are input in the amplification optical fiber 30.

  Further, the coating layer 53 at one end portion connected to the amplification optical fiber 30 in the delivery fiber 50 is peeled off, and a leakage light processing member 60 is provided in the peeling portion.

  As shown in FIG. 4B, the leakage light processing member 60 includes a light-transmitting resin layer 61 that covers the outer peripheral surface of the clad 52 in the delivery fiber 50 and a part of the outer peripheral surface of the resin layer 61. A light-transmitting heat insulating layer 62 to be coated and a metal layer 63 surrounding the outer peripheral surface of the heat insulating layer 62 in close contact with each other.

  The refractive indexes of the heat insulating layer 62 and the resin layer 61 are larger than the refractive index of the cladding 52 in the delivery fiber 50, and the refractive index of the heat insulating layer 62 is equal to or higher than the refractive index of the resin layer 61. Further, the heat conductivity of the heat insulating layer 62 is smaller than the heat conductivity of the metal layer 63, and the glass transition temperature of the heat insulating layer 62 is made higher than the glass transition temperature of the resin layer 61.

  In the case of this embodiment, the light absorption rate of the heat insulation layer 62 is made smaller than the light absorption rate of the resin layer 61, and the thickness of the heat insulation layer 62 is made larger than the thickness of the resin layer 61. Further, the outer shape of the resin layer 61 is a substantially cubic shape, and the outer shapes of the heat insulating layer 62 and the metal layer 63 are a substantially concave box shape.

  Examples of the material constituting the resin layer 61 include urethane-based resins and silicone-based resins. Examples of the material constituting the heat insulating layer 62 include organic materials such as silicone having a glass transition point higher than that of the resin layer 61. In addition, an inorganic material such as quartz to which an element such as germanium that increases the refractive index is added, or heat-resistant glass such as Neoceram or Pyrex (registered trademark) can be used. The material constituting the metal layer 63 is not particularly limited as long as, for example, light is converted into heat, but is preferably a member having excellent heat dissipation properties, such as black anodized aluminum, stainless steel, etc. Is mentioned.

<Operation / Effect>
In the fiber laser device 1 according to the present embodiment, the seed light emitted from the seed light source 10 propagates through the core of the seed optical fiber 15 and is input to the core 31 of the amplification optical fiber 30 by the light input member 40. The seed light input to the core 31 of the amplification optical fiber 30 propagates through the core 31.

  On the other hand, the excitation light emitted from the excitation light source 20 propagates through the core of the excitation optical fiber 22 and is input to the inner cladding 32 of the amplification optical fiber 30 by the light input member 40. The excitation light input to the inner cladding 32 propagates through the inner cladding 32 and the core 31 in the amplification optical fiber 30, and the active element added to the core 31 is excited by the excitation light.

  The active element in the excited state causes stimulated emission by the seed light propagating through the core 31, and the seed light is amplified due to the stimulated emission. The amplified seed light is input to the core 51 of the delivery fiber 50 that is fusion-connected to the output end of the amplification optical fiber 30, propagates through the core 51 of the delivery fiber 50, and is output from the output end.

  By the way, due to axial misalignment between the core 31 of the amplification optical fiber 30 and the core 51 of the delivery fiber 50, mismatch of mode fields, etc., part of the light input to the core 51 of the delivery fiber 50 is clad 52. May leak. In this case, leakage light propagates to the coating layer 53 of the delivery fiber 50, and the coating layer 53 tends to deteriorate due to the leakage light.

  However, in the present embodiment, the leakage light processing member 60 is provided at one end portion of the delivery fiber 50 connected to the amplification optical fiber 30. The leakage light processing member 60 has a light-transmitting resin layer 61 that covers the outer peripheral surface of the cladding 52 of the delivery fiber 50, and the refractive index of the resin layer 61 is larger than the refractive index of the cladding 52. The leakage light processing member 60 has a light-transmitting heat insulating layer 62 that covers a part of the outer peripheral surface of the resin layer 61, and the refractive index of the heat insulating layer 62 is equal to or higher than the refractive index of the resin layer 61.

  For this reason, the light leaking into the clad 52 propagates while being refracted from the resin layer 61 toward the heat insulating layer 62, reaches the metal layer 63 surrounding the outer peripheral surface of the heat insulating layer 62, and is converted into heat by the metal layer 63. And disappear. As a result, it is possible to greatly suppress deterioration of the coating layer 53 due to leakage light.

  In addition, when the refractive index difference between the resin layer 61 and the metal layer 63 is smaller than the refractive index difference between the core 51 and the clad 52 in the delivery fiber 50, the resin layer 61 and the metal layer 63 have the same level. Compared with the case where the difference in refractive index is significantly large, it is possible to reduce the leakage light propagating to the resin layer 61 from being reflected to the delivery fiber 50 side. Therefore, the leaked light propagated to the resin layer 61 can be efficiently converted into heat by the metal layer 63.

  In the present embodiment, the heat conductivity of the heat insulating layer 62 is smaller than the heat conductivity of the metal layer 63, and the glass transition temperature of the heat insulating layer 62 is set higher than the glass transition temperature of the resin layer 61.

  For this reason, the resin layer 61 having a large degree of modification due to heat generated in the metal layer 63 is moved away by the heat insulating layer 62 having a smaller degree of modification than the resin layer 61. Therefore, heat conduction generated in the metal layer 63 with respect to the resin layer 61 can be suppressed by the heat insulating layer 62 whose degree of modification by heat is smaller than that of the resin layer 61. As a result, the heat conduction to the delivery fiber 50 is greatly increased as compared with the case where the delivery fiber 50 and the metal layer 63 are not composed of the resin layer 61 and the heat insulating layer 62 and the resin layer 61 alone is used. Can be suppressed.

  As described above, the leakage light processing member 60 provided in the delivery fiber 50 converts the leakage light into heat, thereby suppressing the deterioration of the coating layer 53 due to the leakage light, and the leakage light processing member for the delivery fiber 50. The heat conduction from 60 can be suppressed. In this way, the fiber laser device 1, the optical amplifier 2, and the leakage light removing component 3 that can improve the life of the delivery fiber 50 are realized.

  In the case of this embodiment, the light absorption rate of the heat insulating layer 62 is made smaller than the light absorption rate of the resin layer 61. In this case, compared with the case where the light absorption rate of the heat insulation layer 62 is larger than the light absorption rate of the resin layer 61, the leakage light propagated to the resin layer 61 can be converted into heat more efficiently by the metal layer 63. .

  In the case of this embodiment, the thickness of the heat insulating layer 62 is made larger than the thickness of the resin layer 61. In this case, the resin layer 61 having a large degree of modification due to heat generated in the metal layer 63 can be kept away from the heat generated in the metal layer 63 by the heat insulating layer 62 having a degree of modification smaller than that of the resin layer 61. . Therefore, the deterioration of the resin layer 61 due to the heat generated in the metal layer 63 can be further reduced.

  In the case of the present embodiment, a leakage light processing member 60 is provided at one end of the delivery fiber 50 connected to the amplification optical fiber 30. For this reason, compared with the case where the leak light processing member 60 is provided in the intermediate part in the delivery fiber 50, the propagation distance of the leak light in the clad 52 of the delivery fiber 50 can be shortened. As a result, it is possible to further suppress the deterioration of the coating layer 53 due to leakage light.

(2) Second Embodiment Next, a second embodiment will be described in detail with reference to FIG. In addition, about the component which is the same as that of 1st Embodiment, or an equivalent component, the overlapping description is abbreviate | omitted except the case where it attaches | subjects the same referential mark and demonstrates especially.

<Configuration of fiber laser device>
FIG. 5 is a diagram illustrating a configuration of a fiber laser device according to the second embodiment. As shown in FIG. 5, the fiber laser device 100 according to the present embodiment is a resonance type fiber laser, and includes a pumping light source 20 (a plurality of laser diodes 21), an optical amplifier 2, a leakage light removing component 3, and a pair of mirrors. The first FBG (Fiber Bragg Grating) 71 and the second FBG 72 are provided as main components.

  The first FBG 71 and the second FBG 72 are arranged on the amplification optical fiber 30 in the optical amplifier 2 with a predetermined distance therebetween.

  The first FBG 71 is provided near the input end of the amplification optical fiber 30 and has a structure in which a high refractive index portion is repeated at a constant period along the longitudinal direction of the amplification optical fiber 30. This portion is adjusted so as to reflect the wavelength of at least part of the light emitted by the active element of the amplification optical fiber 30 in the excited state.

  The second FBG 72 is provided near the output end of the amplification optical fiber 30 and has a structure in which a portion having a high refractive index is repeated at a constant period along the longitudinal direction of the amplification optical fiber 30. This portion is adjusted to reflect light having the same wavelength as the light reflected by the first FBG 71 with a lower reflectance than the first FBG 71.

<Operation / Effect>
In the fiber laser device 100 according to this embodiment, the emitted pumping light propagates through the core of the pumping optical fiber 22 and is input to the inner cladding 32 of the amplification optical fiber 30 by the light input member 40. The pumping light input to the inner cladding 32 propagates through the inner cladding 32 and the core 31 in the amplification optical fiber 30, and the active element added to the core 31 is excited by the pumping light, and has a specific wavelength from the active element. Spontaneous emission light is emitted.

  The spontaneous emission light propagates through the core 31 of the amplification optical fiber 30 and travels between the first FBG 71 and the second FBG 72 and is amplified. A part of the amplified light passes through the second FBG 72 and enters the core 51 of the delivery fiber 50 that is fusion-connected to the output end of the amplification optical fiber 30. Propagate and output from output.

  At this time, even if leakage light propagates to the coating layer 53 of the delivery fiber 50, the leakage light processing member 60 provided in the delivery fiber 50 converts the leakage light into heat, as described above. Thus, deterioration of the coating layer 53 due to the leakage light can be suppressed, and heat conduction from the leakage light processing member 60 to the delivery fiber 50 can be suppressed.

(3) Third Embodiment Next, a third embodiment will be described in detail with reference to FIGS. 6 and 7. In addition, about the component which is the same as that of 1st Embodiment, or an equivalent component, the overlapping description is abbreviate | omitted except the case where it attaches | subjects the same referential mark and demonstrates especially.

<Configuration of fiber laser device>
FIG. 6 is a diagram illustrating a configuration of a fiber laser device according to the third embodiment. As shown in FIG. 6, the fiber laser device 200 in this embodiment includes a plurality of laser light sources 80 and a combiner 90 as main components. The combiner 90 includes a plurality of pumping optical fibers 22, a light input member 91, a leakage light removing component 3, and a light output member 92 as main components.

  The laser light source 80 is a Fabry-Perot type fiber laser. As a pumping light source constituting this fiber laser, a single-chip laser diode or a multi-chip laser diode can be mentioned.

  The light input member 91 is a member that couples the core of the plurality of pumping optical fibers 22 and the core 51 of the delivery fiber 50 in the leakage light removing component 3, and the output side end of the plurality of pumping optical fibers 22 and the delivery fiber. 50 input side end portions.

  FIG. 7 is a view showing the structure of the light input member 91. In FIG. 7, for convenience, the cladding that surrounds the core 22 </ b> A in the excitation optical fiber 22 and the coating layer that covers the cladding are omitted.

  As shown in FIG. 7, the light input member 91 of the present embodiment is a rod-shaped glass body having a tapered portion 91 </ b> A that decreases in diameter from the input end side toward the output end side. The outer peripheral surface other than the end surface of the glass body may be covered with a coating layer.

  The core end surface on the output side of each of the plurality of pumping optical fibers 22 is fused and connected to the end surface on the large diameter side of both ends of the light input member 91. On the other hand, the core end surface on the input side of the delivery fiber 50 is fused and connected to the end surface on the small diameter side of both ends of the light input member 91.

  The light output member 92 is made of, for example, a rod-shaped glass body, and the end face of the light output member 92 is fused and connected to the output end face of the delivery fiber 50.

<Operation / Effect>
In the combiner 90 of the fiber laser device 200 in the present embodiment, the light input member 91 has a tapered portion 91 </ b> A whose diameter decreases from the input side toward the output side. For this reason, in this combiner 90, the NA of the light propagating through the light input member 91 via the plurality of pumping optical fibers 22 exceeds the NA allowed in the subsequent delivery fiber 50, and the core 51 of the delivery fiber 50 is clad. The tendency for light to leak to 52 increases.

  However, in the combiner 90, as described above, the leakage light processing member 60 provided in the subsequent delivery fiber 50 converts the leakage light into heat, so that the deterioration of the covering layer 53 due to the leakage light is suppressed. The heat conduction from the leakage light processing member 60 to the delivery fiber 50 can be suppressed.

(4) Modifications Although the first to third embodiments have been described above as examples, the present invention is not limited to the above embodiments.

  For example, in the first embodiment and the second embodiment, the leakage light processing member 60 is provided in the delivery fiber 50 subsequent to the amplification optical fiber 30. However, a configuration in which the leakage light processing member 60 is also provided to the amplification optical fiber 30 is applicable. When such a form is applied, the leakage light processing member 60 provided in the amplification optical fiber 30 converts light leaking to the outer cladding 33 into heat, as in the above-described embodiment, resulting in the leakage light. It is possible to suppress deterioration of the covering layer 34 to be performed and to suppress heat conduction from the leakage light processing member 60 to the amplification optical fiber 30. As a result, the life of the amplification optical fiber 30 can be improved and the life of the delivery fiber 50 can be improved. When the leakage light processing member 60 is provided in the amplification optical fiber 30, the outer peripheral surface of the outer cladding 33 in the amplification optical fiber 30 is covered with the resin layer 61.

  In the above embodiment, the delivery fiber 50 is applied as an optical fiber provided with the leakage light processing member 60. However, an amplification optical fiber may be applied instead of the delivery fiber 50. In this case, it is possible to secure a larger length of the amplification optical fiber while improving the life of the subsequent amplification optical fiber in which the leakage light processing member 60 is provided. When the leakage light processing member 60 is provided in the amplification optical fiber, the outer peripheral surface of the outer cladding in the amplification optical fiber is covered with the resin layer 61 as described above.

  In addition, as the optical fiber connected to the delivery fiber 50, the amplification optical fiber 30 is applied in the first embodiment and the second embodiment, and a plurality of pumping optical fibers 22 (light input members) are used in the third embodiment. 91) is applied, however, for example, another optical fiber may be applied, or a glass rod having no core may be applied. That is, the front member to be connected to the optical fiber provided with the leakage light processing member 60 may be a glass body. In short, the leakage light removing component only needs to include a core, an optical fiber having a clad having a refractive index lower than that of the core, and a leakage light processing member provided in the optical fiber.

  Moreover, in the said embodiment, although the site | part which provides the leakage light processing member 60 was made into the one end part of an optical fiber, you may be made into parts other than the said one end part. Further, a plurality of leak light processing members 60 may be provided at predetermined intervals or at arbitrary intervals from one end to the other end of the optical fiber. Furthermore, the leak light processing member 60 may be provided over the entire length direction. In addition, when the site | part which bends in an optical fiber is formed, it is preferable to provide the leak light processing member 60 after the said site | part. It is also possible to positively form a bent part and fix it so that the part is maintained.

  Moreover, in the said embodiment, although the shape of the resin layer 61 was made into the substantially cubic shape and the shape of the heat insulation layer 62 and the metal layer 63 was made into the concave box shape, the said resin layer 61, the heat insulation layer 62, and the metal layer 63 of Various shapes can be adopted as the shape. When the boundary surface between the resin layer 61 and the heat insulating layer 62 has an uneven shape, the amount of propagation of leakage light per unit area of the optical fiber covered with the resin layer 61 can be increased. The leakage light propagated to the layer 61 can be efficiently converted into heat by the metal layer 63.

  In the above embodiment, the heat insulating layer 62 that covers a part of the outer peripheral surface of the resin layer 61 and the metal layer 63 that surrounds the outer peripheral surface of the heat insulating layer 62 are applied. However, a heat insulating layer covering the entire outer peripheral surface of the resin layer 61 and a metal layer surrounding the outer peripheral surface of the heat insulating layer 62 may be applied.

  In the above embodiment, unidirectional excitation in which excitation light is input from only one end of the amplification optical fiber 30 is applied. However, bidirectional excitation in which excitation light is input from both ends may be applied.

  The constituent elements of the fiber laser device 1, the fiber laser device 100, the fiber laser device 200, the optical amplifier 2 and the leakage light removing component 3 are appropriately set in addition to the contents shown in the embodiment or the modified example. Combinations, omissions, modifications, additions of well-known techniques, and the like can be made without departing from the scope.

  The optical amplification component, the combiner, and the fiber laser device according to the present invention can be used in industrial fields that handle amplification optical fibers.

DESCRIPTION OF SYMBOLS 1,100,200 ... Fiber laser apparatus 2 ... Optical amplifier 3 ... Leakage light removal component 10 ... Seed light source 20 ... Excitation light source 30 ... Amplification optical fiber 31, 51 ... Core 32 ... Inner cladding 33 ... Outer cladding 34,53 ... Coating layer 40,91 ... Light input member 50 ... Delivery fiber 52 ... Clad 60 ... Leakage light processing member 61 ... Resin layer 62 ... Heat insulation layer 63 ... Metal layer 80 ... Laser light source 90 ... Combiner

Claims (9)

An optical fiber having a core and a cladding having a refractive index lower than that of the core;
A leakage light processing member provided in the optical fiber,
The leakage light processing member is
A light-transmissive resin layer covering the outer peripheral surface of the clad in the optical fiber;
A light-transmissive heat insulating layer covering at least a part of the outer peripheral surface of the resin layer;
A metal layer surrounding the outer peripheral surface of the heat insulating layer,
The refractive index of the heat insulating layer and the resin layer is larger than the refractive index of the cladding in the optical fiber,
The thermal conductivity of the heat insulating layer is smaller than the thermal conductivity of the metal layer,
The leakage light removing component, wherein the glass transition temperature of the heat insulating layer is higher than the glass transition temperature of the resin layer. The leakage light removing component according to claim 1, wherein a thickness of the heat insulating layer is larger than a thickness of the resin layer. The leakage light removing component according to claim 1, wherein a refractive index of the heat insulating layer is larger than a refractive index of the resin layer. The leakage light removing component according to any one of claims 1 to 3, wherein a boundary surface between the heat insulating layer and the resin layer has an uneven shape. The leakage light removing component according to claim 1, wherein the heat insulating layer is made of an inorganic material. A plurality of pump optical fibers for propagating pump light;
An optical fiber disposed downstream of the plurality of excitation optical fibers;
A light input member that couples the core in the plurality of pumping optical fibers and the core in the optical fiber;
A leakage light processing member provided in the optical fiber,
The light input member has a tapered portion that decreases in diameter from the input side toward the output side,
The leakage light processing member is
A light transmissive resin layer covering the outer peripheral surface of the cladding;
A light-transmissive heat insulating layer covering at least a part of the outer peripheral surface of the resin layer;
A metal layer surrounding the outer peripheral surface of the heat insulating layer,
The refractive index of the heat insulating layer and the resin layer is larger than the refractive index of the cladding in the optical fiber,
The thermal conductivity of the heat insulating layer is smaller than the thermal conductivity of the metal layer,
The glass transition temperature of the said heat insulation layer is higher than the glass transition temperature of the said resin layer, The combiner characterized by the above-mentioned. An optical fiber for amplification having a core, an inner cladding and an outer cladding having a lower refractive index than the core; and
A light input member for inputting excitation light to one end of the inner cladding in the amplification optical fiber;
A leakage light processing member provided in the amplification optical fiber,
The leakage light processing member is
A light-transmitting resin layer covering the outer peripheral surface of the outer cladding in the amplification optical fiber;
A light-transmissive heat insulating layer covering at least a part of the outer peripheral surface of the resin layer;
A metal layer surrounding the outer peripheral surface of the heat insulating layer,
The refractive index of the heat insulating layer and the resin layer is larger than the refractive index of the outer cladding in the amplification optical fiber,
The thermal conductivity of the heat insulating layer is smaller than the thermal conductivity of the metal layer,
The glass transition temperature of the said heat insulation layer is higher than the glass transition temperature of the said resin layer, The optical amplifier characterized by the above-mentioned. An optical fiber for amplification having a core, an inner cladding and an outer cladding having a lower refractive index than the core; and
A seed light source and an excitation light source;
A light input member that causes seed light emitted from the seed light source to be input to one end of a core of the amplification optical fiber and that causes excitation light emitted from the excitation light source to be input to one end of an inner cladding of the amplification optical fiber. When,
A leakage light processing member provided in the amplification optical fiber,
The leakage light processing member is
A light-transmitting resin layer covering the outer peripheral surface of the outer cladding in the amplification optical fiber;
A light-transmissive heat insulating layer covering at least a part of the outer peripheral surface of the resin layer;
A metal layer surrounding the outer peripheral surface of the heat insulating layer,
The refractive index of the heat insulating layer and the resin layer is larger than the refractive index of the outer cladding in the amplification optical fiber,
The thermal conductivity of the heat insulating layer is smaller than the thermal conductivity of the metal layer,
The fiber laser device, wherein a glass transition temperature of the heat insulating layer is higher than a glass transition temperature of the resin layer. An optical fiber for amplification having a core, an inner cladding and an outer cladding having a lower refractive index than the core; and
An excitation light source;
A light input member for inputting excitation light emitted from the excitation light source to one end of an inner cladding of the amplification optical fiber;
A pair of mirrors arranged at a predetermined distance from the amplification optical fiber;
A leakage light processing member provided in the amplification optical fiber,
The leakage light processing member is
A light-transmitting resin layer covering the outer peripheral surface of the outer cladding in the amplification optical fiber;
A light-transmissive heat insulating layer covering at least a part of the outer peripheral surface of the resin layer;
A metal layer surrounding the outer peripheral surface of the heat insulating layer,
The refractive index of the heat insulating layer and the resin layer is larger than the refractive index of the outer cladding in the amplification optical fiber,
The thermal conductivity of the heat insulating layer is smaller than the thermal conductivity of the metal layer,
The fiber laser device, wherein a glass transition temperature of the heat insulating layer is higher than a glass transition temperature of the resin layer.

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