JP2008064875A - Optical component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical component that is used in an optical amplifier, and the like, can suppress ASE (amplified spontaneous emission) light from entering in an excitation light source from an optical fiber for amplification, and can easily be manufactured. <P>SOLUTION: The optical component 14A is constituted of a glass tube 41, six optical fibers 42<SB>1</SB>-42<SB>6;</SB>, an optical fiber 43, an optical fiber 44, and resin 45. The glass tube 41 is provided with a through hole between a first end 41a and a second end 41b, where the coating removed part of the six optical fibers 42<SB>1</SB>-42<SB>6</SB>and of the optical fiber 43 are inserted into the through hole. At the position of the first end 41a of the glass tube 41, the six pieces of optical fibers 42<SB>1</SB>-42<SB>6</SB>are arranged in a close-packed structure, in a manner of surrounding the periphery of the optical fiber 43, with the end face of the optical fiber 44 being fusion-spliced to the six optical fibers 42<SB>1</SB>-42<SB>6</SB>, the optical fiber 43, and the glass tube 41 at the respective end faces. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical component including an optical fiber.

  As an optical amplifier or a laser oscillator, an amplification optical fiber to which a rare earth element such as Er element or Yb element is added is used, and excitation light is supplied to the amplification optical fiber to excite the rare earth element. A laser that oscillates is known. Also, in such an optical amplifier or laser oscillator, an optical component disclosed in Patent Document 1 is known as an optical component for introducing pumping light output from a pumping light source into an amplification optical fiber.

  The optical component disclosed in Patent Document 1 uses one optical fiber having a special structure in order to introduce excitation light output from an excitation light source into an amplification optical fiber. That is, this optical fiber has a tapered outer diameter at the end of the tapered portion that emits the pumping light to the amplification optical fiber, and the outer diameter becomes narrower as it is closer to the amplification optical fiber. . Further, this optical fiber has a porous structure including a core for guiding light and a large number of pores surrounding the core region in the separation region on the end side where the excitation light from the excitation light source is incident. It has an air clad and a support layer surrounding the air clad.

In the optical amplifier configured to include the optical component disclosed in Patent Document 1, the pumping light output from the pumping light source is guided to the amplification optical fiber through the core and the tapered portion of the separation region of the optical component. The rare earth element added to the amplification optical fiber is excited. At this time, ASE (Amplified Spontaneous Emission) light is generated in the amplification optical fiber. Part of this ASE light is guided to the outside through the tapered portion of the optical component and the support layer in the separation region. Therefore, the power of the ASE light incident on the excitation light source is reduced, thereby protecting the excitation light source.
JP 2004-341345 A

  However, since the optical component disclosed in Patent Document 1 has a special structure, it is difficult to manufacture. The present invention has been made to solve the above problems, and is an optical component that can be easily manufactured because it can suppress the incidence of ASE light from an amplification optical fiber to an excitation light source used in an optical amplifier or the like. The purpose is to provide.

  An optical component according to the present invention includes: (1) a glass tube having a through hole between a first end and a second end; a plurality of first optical fibers inserted into the through hole of the glass tube; A second optical fiber whose core is optically coupled at the end face to a specific first optical fiber included in the plurality of first optical fibers, and (2) the position of the first end of the glass tube The end face of the second optical fiber is connected to the end faces of the plurality of first optical fibers and the glass tubes, and (3) in the first range along the longitudinal direction including the first end of the glass tubes, The periphery of the bundle of first optical fibers is in contact with the inner wall surface of the glass tube, and the relative positional relationship between the plurality of first optical fibers is fixed. (4) In the longitudinal direction including the second end of the glass tube In the second range, a gap is provided between the plurality of first optical fibers and the glass tube. It is characterized by being.

  This optical component is used, for example, in an optical amplifier. In this case, the second optical fiber included in the optical component is connected to the amplification optical fiber, or may itself be an amplification optical fiber. The light to be amplified is introduced into the amplification optical fiber through a specific first optical fiber included in the plurality of first optical fibers, and further through the second optical fiber. Also, the pumping light output from the pumping light source unit is introduced into the amplification optical fiber through the second optical fiber through the one other than the specific first optical fiber among the plurality of first optical fibers. . Then, the amplified light is optically amplified in the amplification optical fiber. At that time, ASE light is also generated in the amplification optical fiber. Of these, the ASE light traveling toward the optical component passes through the second optical fiber and enters the glass tube and the end faces of the plurality of first optical fibers at the first end of the glass tube. The ASE light incident on the end face of the glass tube is emitted to the outside as it is or through a medium such as resin without returning to the plurality of first optical fibers. For this reason, the incidence of the ASE light to the excitation light source unit is suppressed, and the lifetime and reliability of the excitation light source unit are improved.

  In the optical component according to the present invention, it is preferable that the specific first optical fiber is a single mode optical fiber, and a plurality of the first optical fibers other than the specific first optical fiber are multimode optical fibers. It is. In this case, this optical component is preferable when used in an optical amplifier.

  In the optical component according to the present invention, at the position of the first end of the glass tube, a plurality of first optical fibers other than the specific first optical fiber surround the specific first optical fiber. Is preferred. In this case, it is preferable for optically coupling the cores of the specific first optical fiber and the second optical fiber to each other.

  In the optical component according to the present invention, it is preferable that the resin is filled between the plurality of first optical fibers and the glass tube in the second range. The optical component can be reinforced by filling the resin. Here, the filled resin is preferably transparent at the wavelengths of the excitation light and the ASE light. Further, it is more preferable that the refractive index of the resin is substantially the same as or higher than the refractive index of the glass tube, because ASE light is radiated not only from the second end of the glass tube but also from the resin.

  In the optical component according to the present invention, the first optical fiber other than the specific first optical fiber among the plurality of first optical fibers is a coreless fiber having no core, and is an end face different from the end face connected to the second optical fiber. In addition, it is preferable that another optical fiber having a core is connected. Here, the “other optical fiber” connected to the coreless fiber may be an amplification optical fiber.

  In the optical component according to the present invention, it is preferable that the outer diameter of the glass tube is narrower as it is closer to the first end of the glass tube in a certain range included in the first range.

  In the optical component according to the present invention, it is preferable that the outer diameter of the second optical fiber becomes narrower as the distance from the first end of the glass tube increases within a certain range along the longitudinal direction of the second optical fiber.

  An optical amplifier according to the present invention includes (1) the optical component according to the present invention described above and a pumping light source unit that outputs pumping light, and (2) a second optical fiber included in the optical component or connected thereto. The other optical fiber is an optical fiber for amplification, and (3) the pumping light output from the pumping light source unit is not a specific first optical fiber among the plurality of first optical fibers included in the optical component. (4) The amplified light to be amplified is propagated through the specific first optical fiber and the amplifying optical fiber, and this amplified light is propagated in the amplifying optical fiber. It is characterized by optical amplification. The optical amplifier according to the present invention preferably further includes a photodetector for detecting light emitted from the second end of the glass tube included in the optical component.

  The optical component according to the present invention is used in an optical amplifier or the like, can suppress the incidence of ASE light from an amplification optical fiber to a pumping light source, and can be easily manufactured.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a configuration diagram of a MOPA light source device 1 including an optical amplifier 10 according to the present embodiment. A MOPA (Master Oscillator Power Amplifier) light source device 1 shown in FIG. 1 includes an optical amplifier 10, a seed light source 20, and an optical isolator 30, and the seed light output from the seed light source 20 and passed through the optical isolator 30 is supplied to the optical amplifier 10. It amplifies light and outputs the light amplified light.

The optical amplifier 10 includes six pumping light sources 11 _{1 to} 11 ₆ , six optical fibers 12 _{1 to} 12 ₆ , an optical fiber 13, an optical component 14, and an amplification optical fiber 15. One end of the optical fiber 12 _n is connected to the light emitting end of the excitation light source 11 _n , and the other end of the optical fiber 12 _n is connected to the light incident end of the optical component 14. Note that n is an arbitrary integer from 1 to 6. One end of the optical fiber 13 is connected to the light emitting end of the optical isolator 30, and the other end of the optical fiber 13 is connected to the light incident end of the optical component 14. One end of the amplification optical fiber 15 is connected to the light emission end of the optical component 14, and the other end of the amplification optical fiber 15 is the light emission end of the optical amplifier 10.

  The amplification optical fiber 15 is an optical fiber made of quartz glass to which a rare earth element such as Er element or Yb element is added. By supplying excitation light having a wavelength capable of exciting the added rare earth element, It is possible to optically amplify light to be amplified having a wavelength included in a wavelength band having gain. The amplification optical fiber 15 has a so-called double clad structure, and has a core, an inner clad and an outer clad, and can condense and amplify the light to be amplified in the core, It can be guided by being confined in the inner cladding.

The six pumping light sources 11 _{1 to} 11 ₆ output pumping light having a wavelength capable of pumping the rare earth element added to the amplification optical fiber 15, and preferably include a laser diode. The optical fiber 12 _n inputs the pumping light output from the pumping light source 11 _n to one end and guides the pumping light toward the optical component 14. The optical fiber 13 inputs the seed light output from the seed light source 20 and passed through the optical isolator 30 to one end, and guides the seed light toward the optical component 14.

The optical component 14 inputs the pumping light that has been guided by each of the _six optical fibers 12 _{1 to} 12 _{6 and also} receives the seed light that has been guided by the optical fiber 13, and these pumping lights. The seed light is output to the amplification optical fiber 15. The amplification optical fiber 15 receives pumping light and seed light (amplified light), is excited by the pumping light, optically amplifies the seed light, and outputs the light amplified light.

In the MOPA light source device 1, the seed light output from the seed light source 20 is input to the optical amplifier 10 via the optical isolator 30. In the optical amplifier 10, the pumping light output from the pumping light source 11 _n is propagated from the optical fiber 12 _n and is input to the amplification optical fiber 15 through the optical component 14. The seed light output from the optical isolator 30 and input to the optical amplifier 10 is propagated by the optical fiber 13, passes through the optical component 14, and is input to the amplification optical fiber 15. Then, the seed light is optically amplified in the amplification optical fiber 15, and the light after the optical amplification becomes the output of the optical amplifier 10.

FIG. 2 is a longitudinal sectional view of the optical component 14 according to the present embodiment. The optical component 14 shown in this figure includes a glass tube 41, _six optical fibers 42 _{1 to} 42 ₆ , an optical fiber 43, an optical fiber 44, a resin 45, a resin 46, a resin 47, a resin 48, and a protective tube 49. .

One end side of each of the _six optical fibers 42 _{1 to} 42 ₆ , the optical fiber 43, and the optical fiber 44 is disposed in the protective tube 49, and the coating layer is removed from each one end within a certain range, so that the glass is formed. Exposed. At one end of the protective tube 49, each of the _six optical fibers 42 _{1 to} 42 ₆ and the optical fiber 43 is left in a state where the coating layer is left, and between these optical fibers and the protective tube 49. Is filled with a resin 46. Further, at the other end of the protective tube 49, the optical fiber 44 is left in a state where the coating layer remains, and a resin 47 is filled between the optical fiber 44 and the protective tube 49.

One end of the optical fiber 44 is connected to one end of each of the glass tubes 41, the _six optical fibers 42 _{1 to} 426 and the optical fiber 43 in the internal space of the protective tube 49. The cores of the optical fiber 44 and the optical fiber 43 are optically coupled to each other. The six optical fibers 42 _{1 to} 42 ₆ and the optical fiber 43 in a certain range from the connecting portion are inserted into the through holes of the glass tube 41. A resin 45 is inserted between the _six optical fibers 42 _{1 to} 42 ₆ and the optical fiber 43 and the glass tube 41. Further, the internal space of the protective tube 49 is filled with a resin 48, and holes 49 a and 49 b for injecting the resin into the internal space are provided in the protective tube 49.

The other end of the optical fiber 42 _n is connected to the optical fiber 12 _n . The other end of the optical fiber 43 is connected to the optical fiber 13. The other end of the optical fiber 44 is connected to the optical fiber 15. The optical fiber 42 _n and the optical fiber 12 _n may be a series of optical fibers. The optical fiber 43 and the optical fiber 13 may be a series of optical fibers. Further, the optical fiber 44 and the optical fiber 15 may be a series of optical fibers.

By thus configured optical component 14 is used in the optical amplifier 10, the pumping light outputted from the pumping light source 11 _n passes through the optical fiber 12 _n, the optical fiber 42 _n and the optical fiber 44, the amplifying optical Supplied to the fiber 15. In this way, high-power excitation light can be introduced into the amplification optical fiber 15 using a plurality (six in this embodiment) of excitation light sources. The seed light output from the seed light source 20 and passed through the optical isolator 30 is introduced into the amplification optical fiber 15 through the optical fiber 13, the optical fiber 43, and the optical fiber 44. Then, the seed light is optically amplified in the amplification optical fiber 15 excited by the excitation light.

As pumping light is introduced into the amplification optical fiber 15, ASE light is generated in the amplification optical fiber 15. Of these, the ASE light traveling toward the optical component 14 passes through the optical fiber 44 and enters the glass tube 41, the _six optical fibers 42 _{1 to} 426 and the end surfaces of the optical fiber 43 at the first end of the glass tube 41. . ASE light incident on the end face of the glass tube 41, without returning to the optical fiber 42 ₁ to 42 _6, is radiated to the outside through it or resin, even higher refractive index resin that has returned to the low refractive index layer portion Radiated outside through the layers. Therefore, incidence of the ASE light to the excitation light source ₁₁ 1 to 11 ₆ is suppressed, improving the life and reliability of the pumping light source ₁₁ 1 to 11 ₆ is achieved.

In this optical component 14, the coating removal portions of the _six optical fibers 42 _{1 to} 42 ₆ , the optical fiber 43, and the optical fiber 44 are placed in a protective tube 49 and sealed with resins 46 and 47. It is protected from external force and moisture. The protective tube 49 is preferably made of a material having a thermal expansion coefficient substantially equal to that of these optical fibers, and is preferably made of the same quartz glass as the material of these optical fibers.

Further, also by filling the protective tube 49 with the resin 48, the coating removal portions of the _six optical fibers 42 _{1 to} 42 ₆ , the optical fiber 43 and the optical fiber 44 are protected from vibration and moisture. . The resin 48 preferably has a refractive index lower than the refractive index of the clad of the optical fiber, and is preferably a resin that is cured by ultraviolet irradiation. In this case, the protective tube 49 is preferably made of transparent glass. That is, after injecting resin into the internal space of the protective tube 49 through the holes 49a and 49b of the protective tube 49, ultraviolet light from the outside passes through the protective tube 49 and is irradiated to the resin, thereby curing the resin. Can do.

Next, the principal part of the optical component 14 according to the present embodiment will be described in more detail including modifications. In the description of the optical components 14A to 14E of the following embodiments, those corresponding to the glass tube 41, the optical fiber optical fibers 42 _{1 to} 42 ₆ , the optical fiber 43, the optical fiber 44, and the resin 45 in FIG. 2 are included. A part is demonstrated as a principal part, and description is abbreviate | omitted about the thing corresponded to each of the other resin 46-48 and the protective tube 49, respectively.

FIG. 3 is a cross-sectional view showing an optical component 14A as a first configuration example of the optical component 14 according to the present embodiment. FIG. 2A is a longitudinal sectional view, and FIGS. 2B to 2D are transverse sectional views. As shown in this figure, the optical component 14A includes a glass tube 41, six optical fibers (first optical fibers) 42 _{1 to} 42 ₆ , an optical fiber (specific first optical fiber) 43, and an optical fiber (first optical fiber). 2 optical fiber) 44 and resin 45.

Each of the _six optical fibers 42 _{1 to} 42 ₆ has a core 42a and a clad 42b ((b) and (c) in the figure), and confins the pumping light in the core 42a and guides it in multimode. Can do. Specifically, the outer diameter of the core 42a is 105 μm, the outer diameter of the cladding 42b is 125 μm, the core 42a is made of pure quartz glass, and the cladding 42b is made of quartz glass to which a fluorine element is added.

The optical fiber 43 has a core 43a and a clad 43b ((b) and (c) in the figure), and can confine seed light (amplified light) in the core 43a and guide it in a single mode. Specifically, the outer diameter of the core 43a is about 6 μm, the outer diameter of the clad 43b is 125 μm, the core 43a is made of quartz glass to which GeO ₂ is added, and the clad 43b is made of pure quartz glass.

The optical fiber 44 has a core 44a and an inner clad 44b (FIG. 4D), and the coating layer around the inner clad 44b acts as an outer clad, so that the pump light is sent to the core 44a and the inner clad. It can be confined in 44b and guided in multimode, and seed light (light to be amplified) can be confined in core 44a and guided in single mode. Specifically, the outer diameter of the core 44a is 20 μm, the outer diameter of the clad 44b is 400 μm, the core 44a is made of quartz glass to which GeO ₂ is added, and the clad 44b is made of pure quartz glass. The core 44 a of the optical fiber 44 is optically coupled to the core 43 a of the optical fiber 43.

The glass tube 41 has a through hole between the first end 41a (the side to which the optical fiber 44 is connected) and the second end 41b, and six optical fibers 42 ₁ to 42 _{1 in the} through hole. 42 ₆ and the optical fiber 43 each coating removing portion is inserted. Specifically, the glass tube 41 is made of quartz glass, and has an outer diameter of about 600 μm and an inner diameter of about 500 μm at the position of the second end 41b. FIG. 4B shows a cross-sectional view in the vicinity of the second end 41b, and FIG. 4C shows a cross-sectional view in the vicinity of the first end 41a.

At the position of the first end 41a of the glass tube 41, the six optical fibers 42 _{1 to} 42 ₆ are arranged in a fine structure so as to surround the periphery of the optical fiber 43 ((c) in the figure). At the position of the first end 41 a of the glass tube 41, the end surface of the optical fiber 44 is fusion-bonded to the end surfaces of the six optical fibers 42 _{1 to} 42 ₆ , the optical fiber 43 and the glass tube 41.

In the first range 41c along the longitudinal direction including the first end 41a of the glass tube 41, the periphery of the bundle of _six optical fibers 42 _{1 to} 42 ₆ and the optical fiber 43 is in contact with the inner wall surface of the glass tube 41, The relative positional relationship between these optical fibers is fixed ((c) in the figure).

In the second range 41 d along the longitudinal direction including the second end 41 b of the glass tube 41, a gap is provided between the _six optical fibers 42 _{1 to} 42 ₆ and the optical fiber 43 and the glass tube 41. The gap may be a vacuum, but may be provided with another medium. For example, the gap is preferably a resin 45 ((b) in the figure), but a gas such as an inert gas or air is used. It may be a liquid such as matching oil.

  Further, it is preferable that a reflection reducing film for reducing the reflectance at the wavelength of the fluorescence generated in the amplification optical fiber 15 is formed on the end face of the second end 41 b of the glass tube 41. By doing so, the ASE light generated in the amplification optical fiber 15 and input to the first end 41a of the glass tube 41 is efficiently radiated from the second end 41b of the glass tube 41 to the outside.

FIG. 4 is a diagram illustrating a manufacturing process of the optical component 14A. In this figure, the glass tube 41, the manufacturing process for the optical fiber ₄₂ 1 to 42 ₆ and the optical fiber 43 is shown. _First , as shown in FIG. 6A, _six optical fibers 42 _{1 to} 42 ₆ are arranged so as to surround the optical fiber 43, and these seven optical fibers 42 _{1 to} 42 ₆ , A bundle of 43 is inserted into the glass tube 41A, and in this state, both ends of the glass tube 41A are held by the holders 91 and 92. The glass tube 41A used at this time has an outer diameter (about 600 μm) and an inner diameter (about 500 μm) substantially uniform along the axial direction. At this time, no tension is applied to the seven optical fibers 42 _{1 to} 42 ₆ , 43.

Subsequently, as shown in FIG. 4B, the central region of the glass tube 41A is heated, and the heated central region contracts due to surface tension. For the heating at this time, for example, laser light having a wavelength of 10.6 μm output from a carbon dioxide laser light source, discharge, a micro burner, or the like is used. Thereby, in the central region of the glass tube 41B whose central region has shrunk, the periphery of the bundle of the seven optical fibers 42 _{1 to} 42 ₆ , 43 is in contact with the inner wall surface of the glass tube 41B, and further, there is a hollow portion therebetween. The relative positional relationship between these optical fibers is fixed.

And it is cut | disconnected in the center of the center area | region of the glass tube 41B, as the figure (c) shows. This allows the glass tube 41, and an optical fiber ₄₂ 1 to 42 ₆ and the optical fiber 43 semi-finished products are two sets. Thereafter, the cut surface is polished, and the optical fiber 44 is fused and connected to the cut surface. A resin 45 is filled between the seven optical fibers and the glass tube 41. Thus, the optical component 14A can be easily manufactured.

  When a reflection reducing film is formed on the end surface of the second end 41b of the glass tube 41, the reflection reducing film is formed on both end surfaces of the glass tube 41A prepared in the step of FIG. Is preferably formed. Although the central region of the glass tube 41A is heated in the later step (b) of the figure, the thermal conductivity of the glass is poor, so that the reflection reducing films formed on both end faces of the glass tube 41A are adversely affected by heat. There is nothing.

  If a reflection reducing film is to be formed after the step (b) or (b) in the figure, it is necessary to put it in a film forming apparatus such as a vacuum deposition apparatus together with seven optical fibers. It is cumbersome, and dust and dust adhering to the optical fiber are also put into the film forming apparatus. Furthermore, since gas is released from the resin coating of the optical fiber into the vacuum in the film forming apparatus, it is difficult to perform film formation with high reliability.

The optical component 14A manufactured in this way has a cross-sectional structure as shown in FIG. 3C in the vicinity of the first end 41a of the glass tube 41 (the side to which the optical fiber 44 is connected). The glass tube 41 that has been heated and contracted due to surface tension contracts so as to fill a gap between the bundle of seven optical fibers 42 _{1 to} 42 ₆ , 43.

Moreover, the external shape of each of the seven optical fibers 42 _{1 to} 42 ₆ , 43 may be deformed from a circle. The outer shape of the optical fiber 43 at the center is deformed into a hexagonal shape, and the core portion of the optical fiber 43 is also affected, but since the force is applied symmetrically, there is almost no influence on the propagation mode. Although the surrounding six optical fibers 42 _{1 to} 42 ₆ are subjected to asymmetric deformation, they are multimode fibers, and thus are not affected by an increase in loss.

In this state, the glass tube 41 is only heated and shrunk, and its cross-sectional area is equal to the sum of the cross-sectional areas of the seven optical fibers and the glass tube 41A before heating, and the cross-sectional area is along the axial direction. And uniform. The outer diameter at this time is about 470 μm. Further, if the glass tube 41 is made of pure silica glass and the cladding of each of the _six optical fibers 42 _{1 to} 42 ₆ is made of quartz glass doped with fluorine element, the glass tube 41 and the six optical fibers 42 _{1 to} 42 are formed. _{Between 6} , the light can be guided separately from each other. The maximum diameter of the region where the excitation light is confined is about 350 μm.

When the seven optical fibers 42 _{1 to} 42 ₆ , 43 and the optical fiber 44 are fusion spliced, the mode field diameters of the optical fiber 43 and the optical fiber 44 are different from each other. Although it is about ˜40%, the coupling efficiency can be improved to 70% or more by expanding the core of the optical fiber 43 by thermal diffusion. In addition, although the outer diameter of the bundle of the seven optical fibers 42 _{1 to} 42 ₆ , 43 is larger than the outer diameter of the optical fiber 44, the region where the excitation light is confined in the _six optical fibers 42 _{1 to} 42 ₆ . The outer diameter is narrower than this, and each of the _six optical fibers 42 _{1 to} 42 ₆ can couple the pumping light to the optical fiber 44 with an efficiency of 90 to 95%.

  In addition, it is preferable that the resin 45 filled in the gap formed in the non-shrinked portion of the glass tube 41 has a refractive index substantially equal to or larger than the refractive index of quartz glass. At the time of filling, it is preferable that the resin is injected from a hole provided near the center of the glass tube 41 so that an unfilled portion does not remain inside.

FIG. 5 is a cross-sectional view showing an optical component 14B as a second configuration example of the optical component 14 according to the present embodiment. FIG. 2A is a longitudinal sectional view, and FIGS. 2B to 2D are transverse sectional views. As shown in this figure, the optical component 14B includes a glass tube 41, six optical fibers (first optical fibers) 42 _{1 to} 42 ₆ , an optical fiber (specific first optical fiber) 43, and an optical fiber (first optical fiber). 2 optical fiber) 44 and resin 45.

  Compared with the optical component 14A of the first configuration example previously shown in FIG. 3, the optical component 14B of the second configuration example shown in FIG. 5 is connected to the first end 41a of the glass tube 41 (the optical fiber 44 is connected). The glass tube 41 and the optical fiber 44 are different in that the outer diameters of the glass tube 41 and the optical fiber 44 are substantially equal to each other.

  In order to manufacture such an optical component 14B, in the manufacturing process shown in FIG. 4, the glass tube is previously heated and stretched and stretched to an outer diameter of about 460 μm and a thickness of 20 to 30 μm. What is necessary is just to manufacture according to the process demonstrated using Fig.4 (a)-(c), using as 41A. By doing so, the outer diameter of the cross section (FIG. 5C) at the first end 41a of the glass tube 41 is about 400 μm, and the outer diameter of the cross section of the optical fiber 44 (FIG. 5D). Is approximately equal. A cross section (FIG. 5B) in the vicinity of the second end 41b of the glass tube 41 is substantially the same as that of the first configuration example, but the inner and outer diameters of the glass tube 41 are reduced.

In this optical component 14B, since the outer diameter at the first end 41a of the glass tube 41 is substantially equal to the outer diameter of the optical fiber 44, the core axis of each of the optical fiber 43 and the optical fiber 44 is used when both are fused. Are easy to match each other. In the manufactured optical component 14B, the seed light coupling efficiency between the optical fiber 43 and the optical fiber 44 can be improved. Furthermore, the proportion of ASE light incident on the end face of the glass tube 41 is increased, since the ASE light incident on the excitation light source ₁₁ 1 to 11 ₆ is reduced, which is advantageous in this respect.

FIG. 6 is a cross-sectional view showing an optical component 14 </ b> C as a third configuration example of the optical component 14 according to the present embodiment. The figure (a) is a longitudinal cross-sectional view, and the figure (b)-(e) is a cross-sectional view. As shown in this figure, the optical component 14C includes a glass tube 41, six optical fibers (first optical fibers) 42 _{1 to} 42 ₆ , an optical fiber (specific first optical fiber) 43, and an optical fiber (first optical fiber). 2 optical fiber) 44 and resin 45.

Compared with the optical component 14B of the second configuration example shown in FIG. 5 before, the optical component 14C of the third configuration example shown in FIG. 6 has six optical fibers 42 _{1 to} 42 ₆ each having a core. It is different in that it is a coreless fiber that does not have. ₄₂ 1-42 ₆ Each of these optical fibers made of pure silica glass. The other end of the optical fiber 42 _n is connected to another optical fiber having a core (for example, the optical fiber 12 _n ).

FIG. 2B is a cross-sectional view of the seven optical fibers 12 _{1 to} 12 ₆ , 13. FIG. 4C is a cross-sectional view of the vicinity of the second end 41 b of the glass tube 41. FIG. 4D is a cross-sectional view in the vicinity of the first end 41 a of the glass tube 41. FIG. 4E is a cross-sectional view of the optical fiber 44.

Such an optical component 14C can be manufactured in the same manner as the optical component 14B described above, using coreless fibers as the _six optical fibers 42 _{1 to} 42 ₆ .

In the optical component 14C, in the vicinity of the first end 41a of the glass tube 41, the core 43a of the optical fiber 43 has a high refractive index, whereas the cladding 43b of the optical fiber 43, the optical fibers 42 _{1 to} 42 ₆ and The glass tube 41 has a low refractive index. Further, in the vicinity of the second end 41b of the glass tube 41, the core 43a of the optical fiber 43 has a high refractive index, whereas the cladding 43b of the optical fiber 43, the optical fibers 42 _{1 to} 42 ₆ , the glass tube 41 and Resin 45 has a low refractive index. That is, when the cross section is viewed as a whole, a very large area low refractive index clad is present with respect to the high refractive index core 43a, and the area ratio is from the first end 41a side to the second end. It is large on the 41b side.

Therefore, in the optical part 14C, since never confined to the optical fiber ₄₂ 1 to 42 ₆ and more components of the low NA also the ASE, many of the ASE light is emitted to the space at the second end 41b of the glass tube 41, 7 the ASE light is further reduced incident on the excitation light source ₁₁ 1 to 11 ₆ is a sectional view showing an optical component 14D as a fourth configuration example of the optical component 14 according to the present embodiment. FIG. 2A is a longitudinal sectional view, and FIGS. 2B to 2F are transverse sectional views. As shown in this figure, the optical component 14D includes a glass tube 41, six optical fibers (first optical fibers) 42 _{1 to} 42 ₆ , an optical fiber (specific first optical fiber) 43, and an optical fiber (first optical fiber). 2 optical fiber) 44 and resin 45.

Compared with the optical component 14C of the third configuration example previously shown in FIG. 6, the optical component 14D of the fourth configuration example shown in FIG. 7 includes six optical fibers 42 _{1 to} 42 ₆ and an optical fiber 43. In the fixed range included in the first range 41 c where the periphery of the bundle is in contact with the inner wall surface of the glass tube 41, the outer diameter of the glass tube 41 is narrower as it is closer to the first end 41 a of the glass tube 41. Is different.

FIG. 2B is a cross-sectional view of the seven optical fibers 12 _{1 to} 12 ₆ , 13. FIG. 4C is a cross-sectional view of the vicinity of the second end 41 b of the glass tube 41. FIG. 4D is a cross-sectional view of the large diameter portion in the first range 41 c of the glass tube 41. FIG. 4E is a cross-sectional view of the small diameter portion in the first range 41 c of the glass tube 41. FIG. 5F is a transverse sectional view of the optical fiber 44.

Such an optical component 14D uses coreless fibers as the _six optical fibers 42 _{1 to} 42 _6, respectively, and heats and shrinks the glass tube 41 in the process described with reference to FIG. It can be manufactured by making the outer diameter of the stretched glass tube 41 equal to the outer diameter of the optical fiber 44. In the drawing, the boundary between the core portion of the coreless fiber and the single mode fiber and the glass tube is indicated by a solid line for the sake of convenience. However, the boundary does not actually exist due to fusion.

  In this optical component 14D, a thinner optical fiber 44 can be used. For example, the outer diameter of the core 44a of the optical fiber 44 is 25 μm, and the outer diameter of the cladding 44b is 250 μm. In this case, the coupling efficiency of the pumping light is 80% or more, and the coupling efficiency of the signal light Is at least about 30%.

FIG. 8 is a cross-sectional view showing an optical component 14E as a fifth configuration example of the optical component 14 according to the present embodiment. The figure (a) is a longitudinal cross-sectional view, and the figure (b)-(g) is a cross-sectional view. As shown in this figure, the optical component 14E includes a glass tube 41, six optical fibers (first optical fibers) 42 _{1 to} 42 ₆ , an optical fiber (specific first optical fiber) 43, and an optical fiber (first optical fiber). 2 optical fiber) 44 and resin 45.

  Compared with the optical component 14C of the third configuration example previously shown in FIG. 6, the optical component 14E of the fifth configuration example shown in FIG. 8 has a glass in a certain range along the longitudinal direction of the optical fiber 44. The difference is that the outer diameter of the optical fiber 44 becomes thinner as the distance from the first end 41a of the tube 41 increases.

FIG. 2B is a cross-sectional view of the seven optical fibers 12 _{1 to} 12 ₆ , 13. FIG. 4C is a cross-sectional view of the vicinity of the second end 41 b of the glass tube 41. FIG. 4D is a cross-sectional view in the vicinity of the first end 41 a of the glass tube 41. FIG. 4E is a cross-sectional view of the large diameter portion of the optical fiber 44. FIG. 4F is a transverse cross-sectional view of the small diameter portion of the optical fiber 44. FIG. 5G is a cross-sectional view of the amplification optical fiber 15.

  The optical component 14E can be connected to a thinner optical fiber 15 for amplification.

In the above embodiment, the six optical fibers 42 _{1 to} 42 ₆ are arranged around the optical fiber 43, but a double structure in which twelve optical fibers for guiding the pumping light are further arranged around them. Alternatively, a triple structure in which 18 optical fibers for pumping light guide are arranged may be used.

  This optical component can be applied not only to an optical amplifier but also to supplying pumping light to an amplification optical fiber in a fiber laser oscillator.

  Next, a modification of the optical amplifier according to the present embodiment will be described with reference to FIG. FIG. 9 is a configuration diagram of a MOPA light source device 1A including an optical amplifier 10A according to a modification. Compared to the configuration shown in FIG. 1, the MOPA light source device 1 </ b> A shown in FIG. 9 is different in that an optical amplifier 10 </ b> A is provided instead of the optical amplifier 10. The optical amplifier 10 </ b> A further includes an optical fiber 16 and a photodetector 17 in addition to the configuration of the optical amplifier 10. One end of the optical fiber 16 is connected to the second end of the glass tube 41 included in the optical component 14, and the other end of the optical fiber 16 is connected to the photodetector 17. The light detector 17 detects light emitted from the second end of the glass tube 41 and reaching through the optical fiber 16. Thereby, with a simple configuration, the fluorescence intensity and ASE light when the amplification optical fiber 15 is excited can be measured by the photodetector 17, and parasitic oscillation can be detected. Moreover, it is also possible to measure the reflected light from the object irradiated with the laser light by the photodetector 17. The optical fiber 16 may be fusion-bonded, bonded, or butt-connected to the second end of the glass tube 41, or the tip of the optical fiber 16 may be embedded in the resin in the glass tube 41. The measured or detected signal can be used according to the purpose, such as stabilizing the operation of the optical amplifier 10A, preventing damage, or grasping the state of the apparatus.

1 is a configuration diagram of a MOPA light source device 1 including an optical amplifier 10 according to the present embodiment. It is a longitudinal cross-sectional view of the optical component 14 which concerns on this embodiment. It is sectional drawing which shows 14 A of optical components as a 1st structural example of the optical component 14 which concerns on this embodiment. It is a figure explaining the manufacturing process of 14 A of optical components. It is sectional drawing which shows the optical component 14B as a 2nd structural example of the optical component 14 which concerns on this embodiment. It is sectional drawing which shows 14 C of optical components as a 3rd structural example of the optical component 14 which concerns on this embodiment. It is sectional drawing which shows optical component 14D as a 4th structural example of the optical component 14 which concerns on this embodiment. It is sectional drawing which shows the optical component 14E as a 5th structural example of the optical component 14 which concerns on this embodiment. It is a block diagram of MOPA light source device 1A including optical amplifier 10A which concerns on a modification.

Explanation of symbols

1 ... MOPA light source device, 10 ... optical amplifier, ₁₁ 1 to 11 6 _... pumping light source, ₁₂ 1 to 12 6 _... optical fiber, 13 ... optical fiber, 14,14A～14E ... optics, 15 ... amplifying optical fiber, 20 ... seed light source, 30 ... optical isolator, 41 ... glass tube, ₄₂ 1-42 6 _... optical fiber, 43 ... optical fiber, 44 ... optical fiber, 45 to 48 ... a resin, 49 ... protective tube.

Claims (9)

A glass tube having a through hole between the first end and the second end, a plurality of first optical fibers inserted into the through hole of the glass tube, and a specification included in the plurality of first optical fibers A second optical fiber in which cores are optically coupled to each other at the end face with respect to the first optical fiber,
At the position of the first end of the glass tube, the end surface of the second optical fiber is connected to the end surfaces of the plurality of first optical fibers and the glass tube,
In the first range along the longitudinal direction including the first end of the glass tube, the plurality of first optical fibers bundle is in contact with the inner wall surface of the glass tube, and the plurality of first optical fibers The relative positional relationship of is fixed,
In a second range along the longitudinal direction including the second end of the glass tube, a gap is provided between the plurality of first optical fibers and the glass tube.
An optical component characterized by that.   The specific first optical fiber is a single-mode optical fiber, and the plurality of first optical fibers other than the specific first optical fiber are multimode optical fibers. The optical component according to 1.   At the position of the first end of the glass tube, the plurality of first optical fibers other than the specific first optical fiber surround the periphery of the specific first optical fiber. The optical component according to claim 1.   2. The optical component according to claim 1, wherein in the second range, a resin is filled between the plurality of first optical fibers and the glass tube. Among the plurality of first optical fibers, other than the specific first optical fiber,
A coreless fiber without a core,
Another optical fiber having a core is connected to an end face different from the end face connected to the second optical fiber.
The optical component according to claim 1.   2. The optical component according to claim 1, wherein, in a certain range included in the first range, the outer diameter of the glass tube is narrowed toward the first end of the glass tube.   2. The optical device according to claim 1, wherein the outer diameter of the second optical fiber is narrower as the distance from the first end of the glass tube is longer in a certain range along the longitudinal direction of the second optical fiber. parts. An optical component according to any one of claims 1 to 7, and an excitation light source unit that outputs excitation light,
The second optical fiber included in the optical component or another optical fiber connected to the second optical fiber is an amplification optical fiber,
Excitation light output from the excitation light source unit is introduced into the amplification optical fiber through the one of the plurality of first optical fibers included in the optical component other than the specific first optical fiber,
Amplifying light to be amplified is propagated by the specific first optical fiber and the amplification optical fiber, and the amplification light is optically amplified in the amplification optical fiber;
An optical amplifier characterized by that.   The optical amplifier according to claim 8, further comprising a photodetector that detects light emitted from a second end of the glass tube included in the optical component.

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