JP4969840B2 - Optical fiber structure and optical device - Google Patents

Description

  The present invention relates to an optical fiber structure including an optical fiber whose core contains a laser active substance, and an optical device (for example, an optical amplifier or a laser oscillator) including the optical fiber structure.

  As an optical device including an optical fiber whose core contains a laser active substance, an optical amplifier and a laser oscillator can be cited. In an optical amplifier, pumping light is introduced into an optical fiber to excite a laser active substance, and when amplified light is input to the optical fiber, stimulated emission occurs in the optical fiber, and the amplified light is optically amplified. And output from the optical fiber. In a laser oscillator, an optical fiber is disposed in a resonator, and pumping light is introduced into the optical fiber to excite a laser active material, which causes stimulated emission in the optical fiber and laser oscillation in the resonator. Laser light is output.

  Since such an optical device uses an optical fiber as an optical amplification medium, the number of transverse modes of light amplified or oscillated in the optical fiber is small, and the output light quality is excellent. Therefore, an optical device using an optical fiber as an optical amplification medium can be suitably used for industrial purposes (particularly for machining).

In such an optical device, a method for introducing pumping light into an optical fiber includes an end surface introducing method for introducing pumping light from the end surface of the optical fiber into the core of the optical fiber, and winding the optical fiber. The method is roughly divided into a side surface introduction method for introducing pumping light into the optical fiber cladding from the side surface of the optical fiber structure. Compared with the former end face introduction method, the latter side introduction method has higher efficiency when introducing the pumping light output from the pumping light source into the optical fiber structure, and the pumping light inlet area to the fiber is widened. Therefore, it is possible to use not only a laser diode (LD) alone but also an LD array or LD stack as a pumping light source, so that high power pumping light can be introduced into the optical fiber structure, and therefore optical amplification efficiency Also, the laser oscillation efficiency is excellent, and in this respect, it can be suitably used for industrial use (for example, see Patent Document 1 and Non-Patent Document 1).
Japanese Patent Laid-Open No. 10-190097 2001 New Energy and Industrial Technology Development Organization Consignment Photon Measurement and Processing Technology (Petroleum Production System Advanced Measurement and Processing Technology Research and Development) Results Report, “Chapter VII Highly Concentrated Solid-State Laser Technology: Fiber Laser Research and Development” , Manufacturing Science and Technology Center, March 2002

  In an optical fiber structure and an optical apparatus based on such a side surface introduction method, light output after amplification or oscillation is required to have high power and excellent quality. In order to increase the power of the output light, it is necessary that the input excitation light is efficiently converted into the laser output power. For this purpose, it is required that the pumping light is efficiently absorbed by the laser active substance contained in the core of the optical fiber. From this viewpoint, the ratio of the cross-sectional areas of the core and the clad in the cross section of the optical fiber (core cutting It is desirable that the area / cladding cross-sectional area is large. On the other hand, in order to improve the quality of output light, the core diameter of the optical fiber is required to be small. Therefore, it is desirable to reduce the fiber diameter and the core diameter while maintaining the ratio (core cross-sectional area / cladding cross-sectional area) at a large value.

  In order to increase the power of the output light, it is also required that the power of the pumping light introduced into the optical fiber is large. By using an LD array or LD stack as the excitation light source, the power of the excitation light output from the excitation light source can be increased. However, in reality, the arrangement of a plurality of emitters is not ideal on the light exit surface of the LD array or LD stack and may be disturbed, and the excitation light output from the excitation light source can be converted into an optical fiber structure. For efficient introduction into the body, the thickness of the optical fiber structure is required to be approximately 200 μm or more in an LD array having five or more emitters or a multi-layer LD stack.

  As described above, in the conventional optical fiber structure and optical device, in consideration of using an actual LD array or LD stack as an excitation light source, the thickness of the optical fiber structure must be maintained at approximately 200 μm or more. Therefore, it is difficult to reduce the core diameter and increase the fiber diameter while maintaining the ratio (core cross-sectional area / cladding cross-sectional area) at a large value. Generally, when trying to obtain the single light of the highest quality in the transverse mode, the core diameter is required to be 40 μm or less. Therefore, it is difficult to achieve both high power and high quality of output light.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical fiber structure and an optical device that can easily achieve both high power and high quality of output light.

An optical fiber structure according to the present invention includes an optical fiber in which a plurality of cores containing a laser active substance are arranged in parallel on a predetermined surface in a common clad at a central portion and are individually separated at both ends. And at least a part of the central portion of the optical fiber is wound and laminated in a direction perpendicular to the predetermined surface , and the end surfaces of the cores separated at both ends of the optical fiber are optically separated. And a plurality of cores are connected to form one optical path.

  The optical fiber structure according to the present invention is preferably provided with a reflecting member that reflects light emitted from the laser active material contained in each core of the optical fiber on one end face of the optical path. In addition, the optical fiber structure according to the present invention provides pumping light that introduces pumping light that excites a laser active substance contained in each core of the optical fiber into the optical fiber in the stacked portion of the central portion of the optical fiber. It is preferable to further include an introduction member.

  An optical device according to the present invention includes the above-described optical fiber structure according to the present invention, and a pumping light source that outputs pumping light to be introduced into the optical fiber included in the optical fiber structure. Features. This optical apparatus functions as an optical amplifier or a laser oscillator.

  In the optical fiber structure and the optical device configured as described above, since a plurality of cores exist in the thickness direction in the common clad in the laminated portion of the optical fibers, the ratio (core cross-sectional area / cladding cross-sectional area) ) Can be maintained at a large value, the diameter of each core can be reduced, and the thickness of the cladding can be increased. Therefore, even when an actual LD array or LD stack is used as a pumping light source, pumping light can be efficiently introduced into the optical fiber structure, and output light (amplified output light or laser output) High power and high quality of light) can be easily achieved.

  According to the present invention, it is possible to easily achieve both high power and high quality of output light.

  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 elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
First, a first embodiment of an optical fiber structure and an optical device according to the present invention will be described. 1A and 1B are a plan view and a cross-sectional view of an optical fiber structure 10 according to the first embodiment, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view. 2A and 2B are a perspective view and a sectional view of an optical fiber 11 used in the optical fiber structure 10 according to the first embodiment. FIG. 2A is a perspective view and FIG. 2B is a sectional view. is there.

  As shown in FIG. 2, the optical fiber 11 has two cores 111 and 112. These two cores 111 and 112 are arranged in parallel in the common clad 110 at the center, but are separated individually at both ends. The individual cross-sectional shapes at both end portions are substantially square, and the cross-sectional shape at the central portion is substantially rectangular (a rectangle having a side ratio of 1: 2). These two cores 111 and 112 contain a laser active material that can absorb excitation light of a predetermined wavelength and emit light of other wavelengths. Specifically, the optical fiber 11 is mainly composed of quartz glass. Further, as the laser active material contained in the two cores 111 and 112, any one or combination of trivalent ions of lanthanoid elements such as Yb, Er, Nd, Tm, Ho, Pr, and Ce, or Cr, Illustrative are certain transition metal element ions such as Ti.

As shown in FIG. 1, in the optical fiber structure 10, the optical fiber 11 is densely wound in a spiral shape to have a disk shape. At the time of winding , at least a part of the central portion of the optical fiber 11 (the portion where the two cores 111 and 112 are arranged in parallel in the common clad 110) is placed on the parallel surface of the two cores arranged in parallel. On the other hand, they are stacked in a perpendicular direction to form a disk shape. The optical fiber 11 does not need to be laminated in the direction perpendicular to the disk surface. In this wound state, adjacent clads may be optically connected by fusion or optical resin, but polysilazane (molecular formula: (SiH ₂ NH) _n ) is more preferably used as an adhesive. Connected optically.

Further, the end faces of the cores individually separated at both ends of the optical fiber 11 are optically coupled, and the two cores 111 and 112 are connected to form one optical path. In connection of the core is a preferable to connect each core are on the inner end portion of the optical fiber 11 that is wound as shown in FIG. 1 with each other, out to the outside of the end portion The cores may be connected to each other, or the inner end core 111 and the outer end core 112 may be connected to each other. When connecting the cores, the cores may be fusion-bonded to each other or may be spatially connected using an optical connector or the like. However, in order to reduce connection loss and improve reliability, the cores are fused. Connection is preferred.

  Both end surfaces of the optical path formed by connecting the end surfaces of the two cores 111 and 112 optically may be flat (including oblique) or polished into a spherical surface. In this case, the optical fiber structure 10 is preferably used as an optical amplification medium in an optical amplifier. In other words, the amplified light that has entered the optical path from one end face is optically amplified in the cores 111 and 112 that form a continuous optical path, and the light amplified light is emitted from the other end face. At this time, it is also preferable that a reflection reducing film is provided on both end faces.

  In addition, as shown in FIG. 1, each end face of the two cores 111 and 112 is optically coupled to one end face of the optical path formed in a continuous manner, and is contained in each core of the optical fiber 11. In addition, a reflection member 12 that reflects light emitted from the laser active substance may be provided. In this case, the other end face of the optical path and the reflecting member 12 constitute an optical resonator, and the optical fiber structure 10 is suitably used as an optical amplification medium in a laser oscillator. At this time, it is also preferable that a reflection reducing film is provided on the other end surface (surface from which the laser beam is emitted). In addition, a configuration in which a fiber Bragg grating (FBG) having a reflectance of 10% or less is provided in the vicinity of an end face from which laser light is emitted, and the end face itself is polished obliquely is also preferable. As the reflection member 12, an external mirror, a dielectric multilayer film mirror attached to an end face, an optical fiber grating, or the like is preferably used.

  In addition, a disk-shaped metal plate (not shown) for cooling the optical fiber 11 is provided. The metal plate is in direct or indirect contact with the optical fiber 11 wound in a disk shape, and absorbs heat of the optical fiber 11 generated by absorption of excitation light. In addition, it is also preferable that a low refractive index resin (for example, gel-like fluorosilicone) is provided between the metal plate and the optical fiber 11, and by doing so, at the interface between the resin and the clad 110. Since the excitation light is totally reflected, absorption of the excitation light by the metal plate is prevented and heat transfer between the metal plate and the clad 110 is improved, so that a cooling effect is increased.

  This optical fiber 11 is manufactured as follows. FIG. 3 is a plan view and a cross-sectional view of an optical fiber preform 11A used for manufacturing the optical fiber 11. The optical fiber preform 11A shown in the figure is manufactured as follows. A base material having two circular cross sections is manufactured by a method similar to a method for manufacturing a normal optical fiber base material (for example, MCVD method), and the side surfaces of the two base materials having the circular cross section are ground and polished. The base material has a rectangular cross section with the same dimensions. Then, the two base materials having a rectangular cross section are arranged in parallel, and the respective side surfaces are fused and connected to each other. At the time of this fusion splicing, the fused portions and the unfused portions are alternately provided at a constant period along the longitudinal direction. The unfused portion can be easily formed by providing a recess having a depth of, for example, 0.1 mm on the side surfaces of the two base materials having a rectangular cross section.

  The optical fiber preform 11A manufactured in this manner is obtained by arranging two cores 111A and 112A in parallel in a common clad 110A at the fused portion (FIG. 5B), and is not fused. In the portion, the cores 111A and 112A are individually separated ((c) in the figure). The optical fiber 11 can be obtained by drawing the optical fiber preform 11A and cutting the unfused portion. By appropriately setting various conditions for drawing, the cross-sectional shape of the optical fiber 11 obtained by drawing remains substantially rectangular, and the portion that has not been fused in the base material is the light after drawing. The fiber 11 remains unfused.

  FIG. 4 is a plan view of the optical device 1 including the optical fiber structure 10 according to the first embodiment. In addition to the configuration shown in FIG. 1, the optical device 1 includes a plurality of sets of excitation light introducing members 13, optical systems 14, and excitation light sources 15 as means for introducing excitation light into the optical fiber structure 10. . The pumping light source 15 outputs pumping light to be introduced into the optical fiber 11 included in the optical fiber structure 10, and is, for example, an LD. Preferably, a plurality of LD emitters are arranged one-dimensionally. An LD array or an LD stack in which a plurality of LD arrays are stacked. As the wavelength of the excitation light, a wavelength that can excite the laser active substance contained in the cores 111 and 112 of the optical fiber 11 is selected. The optical system 14 collimates and further converges the excitation light output from the excitation light source 15 and causes the converged excitation light to enter the incident surface 131 at one end of the excitation light introducing member 13.

  The excitation light introducing member 13 introduces the excitation light output from the excitation light source 15 and input to the incident surface 131 through the optical system 14 into the optical fiber 11 in the stacked portion of the central portion of the optical fiber 11. The excitation light introducing member 13 is made of a material having a small absorption at the excitation light wavelength, preferably synthetic quartz glass, and may be multicomponent glass, and more preferably the refractive index of the clad of the optical fiber. Has a higher refractive index. Moreover, it is preferable that the excitation light introducing member 13 is provided so that the excitation light after introduction propagates in the extending direction of the cores 111 and 112.

  FIG. 5 is a plan view and a side view of the excitation light introducing member 13, the optical system 14, and the excitation light source 15. FIG. 5 (a) is a plan view, and FIG. 5 (b) is a side view. In this figure, the excitation light source 15 is an LD stack in which two LD arrays are stacked. The optical system 14 includes a first collimator 141, a second collimator 142, and a condenser lens 143. The first collimator 141 receives the excitation light output from each emitter of the LD stack as the excitation light source 15 and collimates the excitation light with respect to the fast axis. The second collimator 142 receives the excitation light output from the first collimator 141 and collimates the excitation light with respect to the slow axis. The condenser lens 143 receives the excitation light converted into parallel light by the first collimator 141 and the second collimator 142, converges the excitation light, and makes the converged excitation light incident on the excitation light introducing member 13. Incident on the surface 131.

  FIG. 6 is a side view of the optical fiber 11, the excitation light introducing member 13, the optical system 14, and the excitation light source 15. The excitation light introducing member 13 guides the excitation light input from the optical system 14 to the incident surface 131 at one end while totally reflecting the upper and lower surfaces, and the guided excitation light from the other end side to the optical fiber 11. Introduce in. The upper surface and the lower surface of the excitation light introducing member 13 are planes parallel to each other, and on the other end side (the side where the excitation light is introduced into the optical fiber 11) of the excitation light introducing member 13, an inclined surface inclined with respect to the lower surface 132 is provided. The lower surface below the inclined surface 132 is optically connected to the side surface of the optical fiber 11. The inclined surface 132 forms an angle of several degrees to several tens of degrees with respect to the lower surface, has an optical polishing or a smooth surface corresponding thereto, and the excitation light that has guided the inside of the excitation light introducing member 13. (Shown by a dotted line in the figure) is totally reflected and introduced into the optical fiber 11.

  The optical device 1 configured as described above operates as follows. The excitation light output from the excitation light source 15 is collected by the optical system 14, is incident on the incident surface 131 of the excitation light introducing member 13, is guided inside the excitation light introducing member 13, and the excitation light introducing member 13 It is totally reflected by the inclined surface 132. The excitation light totally reflected by the inclined surface 132 is introduced into the optical fiber 11 through a portion where the lower surface of the excitation light introducing member 13 and the side surface of the optical fiber 11 are optically connected. The excitation light introduced into the optical fiber 11 excites the laser active substance contained in the cores 111 and 112 while being guided through the optical fiber 11 while being totally reflected at the outer interface of the clad 110.

  When the optical apparatus 1 does not include the reflecting member 12 and operates as an optical amplifier, when the light to be amplified is input to one end of the optical path connected to the cores 111 and 112, the input light to be amplified is the core 111. , 112 are optically amplified while being guided, and the optically amplified light is output from the other end of the optical path. On the other hand, when the optical device 1 includes the reflecting member 12 and operates as a laser oscillator, stimulated emission is generated by the excited laser active material, and laser oscillation is performed in the resonator to output laser light.

  In the optical device 1 and the optical fiber structure 10 according to the present embodiment, the two cores 111 and 112 of the optical fiber 11 contain a laser active substance that is excited by excitation light, and are common in the central portion. While being parallel in the clad 110, both ends are separated individually. Further, at least a part of the central portion of the optical fiber 11 is laminated in a direction perpendicular to the parallel surfaces of the two parallel cores 111 and 112 to have a disk shape. Furthermore, the end surfaces of the cores individually separated at both ends of the optical fiber 11 are optically coupled, and the two cores are connected to form one optical path. Then, as shown in FIG. 6, the excitation light introduced into the optical fiber 11 by the excitation light introducing member 13 from the side of the optical fiber structure 10 having a disk shape is totally reflected by the upper and lower surfaces of the disk. While being guided in the optical fiber 11, the laser active substance contained in the cores 111 and 112 is excited.

  From the above, in this embodiment, since the two cores 111 and 112 exist in the thickness direction in the common cladding 110 in the disk-shaped portion of the optical fiber 11, the ratio (core cross-sectional area / cladding) The diameter of the cores 111 and 112 can be reduced and the thickness of the clad 110 can be increased while maintaining a large value (cross-sectional area). Therefore, even when an actual LD array or LD stack is used as a pumping light source, pumping light can be efficiently introduced into the optical fiber structure 10 and output light (amplified output light or laser) High power and high quality of output light) can be easily achieved.

  Furthermore, the optical device 1 and the optical fiber structure 10 according to the present embodiment can also achieve the following effects. That is, in this embodiment, as shown in FIG. 1, in the optical fiber structure 10, the central portion of the optical fiber 11 is densely wound in a spiral shape and is perpendicular to the parallel surface of the two cores. The optical fibers 11 do not need to be laminated in a direction perpendicular to the disk surface, while being laminated in a direction to form a disk shape. From this, the optical fiber structure 10 in which two cores exist in the thickness direction can be easily manufactured.

  In addition, since the two cores are individually separated at both ends of the optical fiber 11, each separated cladding size can be set to the same level as that of a normal communication optical fiber (125 μm). Therefore, high-quality fusion splicing is possible without special know-how. For example, when the optical device 1 is used as an optical amplifier, the connection between the general-purpose fiber for introducing the amplified light and the optical fiber 11 is facilitated. In addition, end face processing at both ends of the optical fiber 11, end face flattening by breakage, fusion bonding of obliquely polished fibers, connection of end caps, and the like are also easy. Furthermore, it is easy to multiplex the light output from each of the plurality of optical devices 1 by an optical coupler configured using an optical fiber having a large core / cladding ratio, and the quality of the light after the multiplexing is also improved. Can be kept high.

(Second Embodiment)
Next, a second embodiment of the optical fiber structure and the optical device according to the present invention will be described. 7A and 7B are a perspective view and a cross-sectional view of the optical fiber structure 20 according to the second embodiment, where FIG. 7A is a perspective view and FIG. 7B is a cross-sectional view. The optical fiber 21 used here has the same configuration as that shown in FIG.

As shown in FIG. 7, in the optical fiber structure 20, the optical fiber 21 is densely wound spirally around a cylindrical cooling member 29. At the time of this winding , at least a part of the central portion of the optical fiber 21 (the portion where the two cores 211 and 212 are arranged in parallel in the common clad 210) is placed on the parallel surface of the two cores arranged in parallel. The cylinders are stacked in a direction perpendicular to the cylinder. The optical fiber 21 does not need to be laminated in the radial direction of the cylinder shape. In this wound state, adjacent clads are optically connected by fusion or optical resin.

In addition, the end surfaces of the cores individually separated at both ends of the optical fiber 21 are optically coupled, and the two cores 211 and 212 are connected to form one optical path. In connection of the core is a preferable to connect each core are on the one end of the optical fiber 21 that is wound as shown in FIG. 7 to one another, the core 211 at one end And the core 212 at the other end may be connected to each other. When connecting the cores, the cores may be fusion-bonded to each other or may be spatially connected using an optical connector or the like. However, in order to reduce connection loss and improve reliability, the cores are fused. Connection is preferred.

  Both end surfaces of the optical path formed by connecting the end surfaces of the two cores 211 and 212 optically may be polished flat. In this case, the optical fiber structure 20 is preferably used as an optical amplification medium in an optical amplifier. That is, the amplified light that has entered the optical path from one end face is optically amplified in the cores 211 and 212 that are connected to each other, and the light amplified light is emitted from the other end face. At this time, it is also preferable that a reflection reducing film is provided on both end faces. In addition, a configuration in which a fiber Bragg grating (FBG) having a reflectance of 10% or less is provided in the vicinity of an end face from which laser light is emitted, and the end face itself is polished obliquely is also preferable.

  In addition, as shown in FIG. 7, each end face of the two cores 211 and 212 is optically coupled to one end face of the optical path formed in a continuous manner, and is contained in each core of the optical fiber 21. In addition, a reflection member 22 that reflects light emitted from the laser active substance may be provided. In this case, the other end face of the optical path and the reflecting member 22 constitute an optical resonator, and the optical fiber structure 20 is suitably used as an optical amplification medium in a laser oscillator. At this time, it is also preferable that a reflection reducing film is provided on the other end surface (surface from which the laser beam is emitted). As the reflecting member 22, an external mirror, a dielectric multilayer film mirror attached to an end face, an optical fiber grating, or the like is preferably used.

  The cooling member 29 is made of metal and is used for cooling the optical fiber 21. It is preferable that a hole for flowing circulating cooling water is provided inside the cooling member 29. The cooling member 29 is in direct or indirect contact with the optical fiber 21 wound in a cylinder shape and absorbs heat of the optical fiber 21 generated by absorption of excitation light. In addition, it is also preferable that a low refractive index resin (for example, fluorosilicone) is provided between the cooling member 29 and the optical fiber 21. By doing so, excitation light is generated at the interface between the resin and the clad 210. Is totally reflected, the absorption of excitation light is prevented by the metal plate, and the heat transfer between the cooling member 29 and the clad 210 is improved, so that the cooling effect is increased.

  FIG. 8 is a plan view of the optical device 2 including the optical fiber structure 20 according to the second embodiment. In addition to the configuration shown in FIG. 7, the optical device 2 includes a plurality of sets of excitation light introducing members 23, an optical system 24, and excitation light sources 25 as means for introducing excitation light into the optical fiber structure 20. . Each of the excitation light introducing member 23, the optical system 24, and the excitation light source 25 in the present embodiment has the same configuration as the excitation light introducing member 13, the optical system 14, and the excitation light source 15 in the first embodiment liquid.

  The optical device 2 according to the present embodiment configured as described above operates in the same manner as the optical device 1 according to the first embodiment, and can achieve the same effects.

(Third embodiment)
Next, a third embodiment of the optical fiber structure and the optical device according to the present invention will be described. 9A and 9B are a perspective view and a cross-sectional view of an optical fiber structure 30 according to the third embodiment, where FIG. 9A is a perspective view and FIG. 9B is a cross-sectional view. The optical fiber 31 used here has the same configuration as that shown in FIG.

  As shown in FIG. 9, in the optical fiber structure 30, a plurality of optical fibers 31 are folded back, and a central portion (two pieces of optical fibers 31) between a certain folding point and the next folding point. At least a part of a portion in which the cores 311 and 312 are arranged in parallel in the common clad 310 is laminated in a direction perpendicular to the parallel surface of the two parallel cores to have a flat plate shape. . The optical fiber 31 need not be laminated in the thickness direction of the flat plate shape. In this laminated state, adjacent clads are optically connected by fusion or optical resin.

  Further, the end surfaces of the cores individually separated at both ends of the optical fiber 31 are optically coupled, and the two cores 311 and 312 are connected to form one optical path. When connecting the cores, it is preferable to connect the cores at one end of the optical fiber 31 to each other as shown in FIG. 9, but the core 311 at one end and the other end are connected. The cores 312 may be connected to each other. When connecting the cores, the cores may be fusion-bonded to each other or may be spatially connected using an optical connector or the like. However, in order to reduce connection loss and improve reliability, the cores are fused. Connection is preferred.

  Both end surfaces of the optical path formed by connecting the end surfaces of the two cores 311 and 312 in an optically connected manner may be polished flat. In this case, the optical fiber structure 30 is preferably used as an optical amplification medium in the optical amplifier. That is, the amplified light that has entered the optical path from one end face is optically amplified in the cores 311 and 312 that are connected to each other, and the light amplified light is emitted from the other end face. At this time, it is also preferable that a reflection reducing film is provided on both end faces.

  Further, as shown in FIG. 9, each end face of the two cores 311, 312 is optically coupled to one end face of the optical path formed in a continuous manner, and is contained in each core of the optical fiber 31. In addition, a reflection member 32 that reflects light emitted from the laser active substance may be provided. In this case, the other end face of the optical path and the reflecting member 32 constitute an optical resonator, and the optical fiber structure 30 is suitably used as an optical amplification medium in the laser oscillator. At this time, it is also preferable that a reflection reducing film is provided on the other end surface (surface from which the laser beam is emitted). In addition, a configuration in which a fiber Bragg grating (FBG) having a reflectance of 10% or less is provided in the vicinity of an end face from which laser light is emitted, and the end face itself is polished obliquely is also preferable. As the reflecting member 32, an external mirror, a dielectric multilayer film mirror attached to an end face, an optical fiber grating, or the like is preferably used.

  A flat metal plate (not shown) for cooling the optical fiber 31 is preferably provided. The metal plate is in direct or indirect contact with the optical fiber 31 laminated in a flat plate shape, and absorbs heat of the optical fiber 31 generated by absorption of excitation light. In addition, it is preferable that a low refractive index resin (for example, fluorosilicone) is provided between the metal plate and the optical fiber 31. By doing so, excitation light is generated at the interface between the resin and the clad 310. Since the light is totally reflected, absorption of excitation light is prevented by the metal plate, and heat transfer between the metal plate and the clad 310 is improved, so that a cooling effect is increased.

  The optical fiber structure 30 according to the third embodiment is further provided with the same pumping light introducing section, optical system, and pumping light source as those in the first embodiment or the second embodiment. An optical device (optical amplifier or laser oscillator) is configured. The optical device according to this embodiment configured as described above operates in the same manner as the optical devices 1 and 2 according to the first embodiment or the second embodiment, and can provide the same effects.

(Fourth embodiment)
Next, a fourth embodiment of the optical device according to the present invention will be described. FIG. 10 is a configuration diagram of the optical device 4 according to the fourth embodiment. The optical device 4 includes a plurality of (here, three) optical fiber structures 40 ₁ to 40 ₃ connected in series, and a plurality of cores included in each optical fiber are connected to form one optical path. It is what. Each of the optical fiber structures 40 ₁ to 40 ₃ has the same configuration as the optical fiber structures 10, 20, and 30 according to the above-described embodiments. In this figure, the means (excitation light source, optical system, and excitation light introducing member) for introducing excitation light into each of the optical fiber structures 40 ₁ to 40 ₃ are not shown.

Both end faces of one optical path formed by connecting a plurality of cores included in each optical fiber may be polished flat. In this case, the optical fiber structures 40 ₁ to 40 ₃ are preferably used as an optical amplification medium in the optical amplifier. That is, the amplified light that has entered the optical path from one end face is optically amplified in the core that forms a continuous optical path, and the light amplified light is emitted from the other end face. At this time, it is also preferable that a reflection reducing film is provided on both end faces.

In addition, as shown in FIG. 10, the laser active material contained in each core emits to one end surface of one optical path formed by connecting a plurality of cores included in each optical fiber. A reflecting member 42 that reflects the light to be emitted may be provided. In this case, the other end face of the optical path and the reflecting member 42 constitute an optical resonator, and the optical fiber structures 40 ₁ to 40 ₃ are preferably used as an optical amplification medium in the laser oscillator. At this time, it is also preferable that a reflection reducing film is provided on the other end surface (surface from which the laser beam is emitted). In addition, a configuration in which a fiber Bragg grating (FBG) having a reflectance of 10% or less is provided in the vicinity of an end face from which laser light is emitted, and the end face itself is polished obliquely is also preferable. As the reflecting member 42, an external mirror, a dielectric multilayer film mirror attached to an end face, an optical fiber grating, or the like is preferably used.

(Other embodiments)
The present invention is not limited to the above embodiment, and various modifications can be made. For example, the number of cores included in the optical fiber is 2 in the above embodiment, but may be 3 or more. The form of optical fiber lamination is not limited to the above embodiment, and at least a part of the central portion of the optical fiber is laminated in a direction perpendicular to the parallel surface of the parallel cores. It only has to be.

  Next, specific examples of the optical fiber structure and the optical device according to the present invention will be described.

Example 1
The optical fiber structure and optical device of Example 1 correspond to the first embodiment described above. The optical fiber structure and optical device of Example 1 were manufactured as follows. First, two optical fiber preforms (core diameter 3 mm, cladding diameter 13 mm, length 500 mm) were produced by MCVD. 1.3 wt% Yb ³⁺ ions were added to the core of each optical fiber preform. At this added concentration, the absorption coefficient at a wavelength of 976.5 nm is 900 dB / m to 950 dB / m. The numerical aperture NA of the optical fiber estimated from the refractive index distribution of this optical fiber preform was approximately 0.07.

  Each of these two optical fiber preforms is ground and polished so that the cross-sectional shape is a square with a side length of 8.3 mm, and the two optical fiber preforms are arranged in parallel. The respective side surfaces were fused and connected to each other. At the time of this fusion splicing, as shown in FIG. 3, unfused portions of 5 mm were periodically formed every 19 mm in the longitudinal direction. The formation of the unfused portion is facilitated by providing a recess having a maximum depth of 0.1 mm over a length of 5 mm at intervals of 19 mm in advance on the side surfaces to be connected to the two optical fiber preforms. .

  The optical fiber preform fused as described above was drawn by a drawing apparatus to produce an optical fiber having a rectangular cross-sectional shape of 0.11 mm × 0.22 mm. At this time, in the portion where the unfused portion of the optical fiber preform was drawn, square optical fibers having a cross-sectional shape of 0.11 mm × 0.11 mm were formed into fibers without being bonded to each other. As a result, the produced optical fibers are fused approximately 110 m, the cross-sectional shape is rectangular and the array type fiber part (fused part) including two cores, and approximately 30 m separated from each other. The non-fused separation portion having a square cross section that encloses the core of the above was of a periodic separation type in which the core is periodically distributed. The core diameter was about 40 μm.

  The optical fiber thus produced was separated so as to have an approximately 2 m unfused separation part on both sides of the approximately 110 m fused part, and an optical fiber as shown in FIG. 2 was obtained. Then, as shown in FIG. 1, the fused portion of the optical fiber is tightly wound around a reel so as to be stacked in a direction perpendicular to the parallel surface of the two parallel cores, and a disk shape is obtained. did. Further, adjacent clads in this wound state were connected by a heat-resistant optical resin. The refractive index of this optical resin was adjusted within about ± 3% around the refractive index of 1.4585 of the clad glass. The disk-shaped optical fiber structure thus produced had an outer diameter of about 220 mm, an inner diameter of about 184 mm, and a thickness of 0.22 mm.

  Next, as shown in FIG. 4, 20 pumping light introducing members were optically connected to the upper surface of the disk-shaped optical fiber structure at equal intervals in the circumferential direction. Each excitation light introducing member has a substantially flat plate shape made of synthetic quartz glass, has a rectangular shape of 0.22 mm × 2.5 mm in cross section, is 80 mm in length, and totally reflects the excitation light. The angle between the inclined surface and the lower surface for introduction into the optical fiber was 4 degrees. At this time, the same optical resin as that used for the connection between the clads of the optical fiber was used for bonding the excitation light introducing member and the optical fiber.

  As an excitation light source provided corresponding to each excitation light introducing member, an LD stack having two emitter rows was used. As shown in FIG. 5, the excitation light (wavelength 977 nm) emitted from each emitter is made substantially parallel light with respect to both the fast axis and the slow axis by two collimators, and is perpendicular to the excitation light introducing member by a condensing lens. Incident on the polished end face. As shown in FIG. 6, the excitation light input to the excitation light introducing member was introduced into the optical fiber having a disk shape. At this time, the maximum dispersion angle of the excitation light was about 6 ° in this example.

  Next, each of the two end faces in the separated unfused portion drawn out to the inside of the disk-shaped optical fiber structure is polished to a flat surface, and these two end faces are obtained by an optical fiber fuser using discharge heating. The cores were aligned and fusion spliced. This connection loss was 0.1 dB or less. By connecting in this way, the optical fibers constituting the optical fiber structure are connected together. As a result, the output from the core of the optical fiber is 2 of the separated unfused portion drawn from the outside of the optical fiber structure. It was limited to emission from the end face of the location. The optical device at this time is used as an optical amplifier.

  Further, the two end faces of the outer separated unfused portion are polished to a flat surface in the same manner as the inner side, and either one of the end faces reflects a dielectric multilayer film having a reflectance of 99.9% (@wavelength 1100 ± 5 nm). The laser output was limited to one direction by abutting and connecting the mirror. At this time, the end face on the output light extraction side had a reflectance of about 4% of Fresnel reflection. The optical device at this time is used as a laser oscillator.

The average power of pumping light (continuous light) output from each LD stack as the pumping light source was 80 W. Therefore, a total of 1600 W of excitation light was input to the optical fiber structure. At this time, the excitation light from the excitation light source was condensed to an average height of 200 μm and a width of 2.5 mm (1 / e ² ) on the end face of each excitation light guide member. The central wavelength of the excitation light was 977 ± 2 nm at the maximum output. Further, the optical fiber structure including the excitation light source was cooled by a water flow of 20 ° C. As a result, an output laser beam of approximately 1100 W was obtained from the optical device as a laser oscillator. Further, when the beam quality was measured, M2 was about 1.46.

(Example 2)
The optical fiber structure and optical device of Example 2 also correspond to the first embodiment described above. Also in Example 2, an optical fiber having two cores was manufactured in the same manner as Example 1 described above. The optical fiber used in Example 2 was the same as that in Example 1 described above.
However, the core diameter of the optical fiber used in Example 2 was about 30 μm.

  Using such an optical fiber, a disk-shaped optical fiber structure was produced in the same manner as in Example 1. However, in Example 2, the clads adjacent to each other in the wound state were connected by an inorganic polymer adhesive. The disk-shaped optical fiber structure had an outer diameter of about 157 mm, an inner diameter of about 144 mm, and a thickness of 0.22 mm. Further, an output folding mirror having a reflectance of 99.9% (@wavelength 1100 ± 5 nm) was installed on one of the two end faces of the outer separated unfused portion.

  Twelve excitation light introducing members were optically connected to the upper surface of the disk-shaped optical fiber structure at equal intervals in the circumferential direction. The average power of pumping light (continuous light, wavelength 977 nm) output from each LD stack as the pumping light source was 80 W. Therefore, a total of 960 W of excitation light was input to the optical fiber structure. As a result, an output laser beam of approximately 6400 W was obtained from the optical device as a laser oscillator. When the beam quality was measured, M2 was about 1.31. Further, when the near-field pattern of the emitted laser beam was observed, it was the shape of the fundamental mode light of a normal optical fiber, was circularly symmetric, and no nodes were seen. Therefore, it is considered that the laser propagation in the optical fiber is substantially single mode.

  The output folding mirror was removed, and a single mode fiber (commercial product) having a mode field diameter of 10 μm was fused and connected to this end face, and laser light having a wavelength of 1080 nm was introduced as seed light (light to be amplified). When the seed light was modulated and introduced as a pulse with a peak intensity of 10 W, a repetition of 20 kHz, and a peak width of 20 ns, the seed light was amplified and output with a peak intensity of 35 kW. That is, an amplification gain of about 35 dB was obtained. The excitation light intensity at this time was 120 W in total.

  When used as an optical amplifier, an output transmission fiber was fused and connected to the fiber end face on the output extraction side. This output transmission fiber has a circular cross section with a core diameter of 30 μm, NA of 0.07, no Yb added, and a cladding diameter of 125 μm. Further, a coreless quartz glass rod having a diameter of 2 mm and a length of 2 mm was received as an end cap at the tip of the output transmission fiber. The end cap was subjected to 8 ° oblique polishing and further subjected to a reflection reducing coating at a wavelength of 1080 nm. This is to suppress self-excited oscillation.

  Compared with Example 1, in Example 2, the number of pumping light introducing members was reduced and the loss of pumping light was reduced so that pumping efficiency was not lowered even if the effective absorption coefficient of pumping light in the optical fiber was low. . As a result, the core diameter can be further reduced, and the core diameter of the optical fiber used for the high output type is almost the same as the end face introduction method of introducing the pumping light from the end face of the optical fiber. In Example 2, the oscillation was substantially single mode inside the optical fiber.

  Here, there is an operation of winding an optical fiber around a cylinder having a diameter of about 100 mm in order to make the energy distribution ratio of the base mode light overwhelmingly higher than other higher-order mode light by the end face introduction method. The core of the optical fiber structure originally has a circular structure. In Example 2, the higher-order mode is efficiently suppressed by setting the diameter of the winding of the disk to about φ150. In the example of the end face introduction method described above, the clad diameter is 400 μm or more, but in the present invention, the clad width can be reduced to about 110 μm. For this reason, the bending loss that the core propagation mode receives is larger than that of the φ400 μm cladding, so that higher-order modes can be suppressed even when winding relatively loosely.

(Example 3)
The optical fiber structure and the optical device of Example 3 also correspond to the first embodiment described above. Also in Example 3, an optical fiber having two cores was produced in the same manner as in Example 1 described above. The optical fiber used in Example 3 was the same as that in Example 1 described above.

Using such an optical fiber, a disk-shaped optical fiber structure was produced in the same manner as in Example 1. However, in Example 3, the adjacent clads in the wound state were fused by condensing and irradiating CO ₂ laser light to locally heat the clad surface portion. In this fusion splicing, the optical fiber structure is also heated to 1100 ° C. or higher by using a planar high-temperature heater (maximum heating temperature 1700 ° C.) having the same size and shape as the optical fiber structure main body. Is possible. At this time, the clad may not be fused so that there is no gap between them, and if the pumping light introduction method follows the flow of the optical fiber, the pumping light can be efficiently and efficiently coupled. Can do.

  In addition, a laser grating with a reflectivity of 99.9% (@wavelength 1100 ± 5 nm) is fused and connected to one of the two end faces of the outer separated unfused portion, thereby reducing the laser output. Limited to direction. At this time, the end face of the optical fiber on the output extraction side had a reflectance of about 4% of the Fresnel reflection.

  Subsequently, twelve excitation light introducing members were optically connected to the upper surface of the disk-shaped optical fiber structure at equal intervals in the circumferential direction. Each excitation light introducing member has a substantially flat plate shape made of multicomponent glass, has a cross-sectional shape of a rectangle of 0.22 mm × 2.5 mm, a length of 80 mm, and totally reflects the excitation light. The angle between the inclined surface and the lower surface for introduction into the optical fiber was 4 degrees.

  The multi-component glass constituting the excitation light introducing member has a refractive index of 1.48 and a softening temperature of 800 ° C. Therefore, the excitation light introducing member is installed on the upper surface of the optical fiber structure, and the platinum light beam heated to about 1000 ° C. with a small heater is pressed to fuse the excitation light introducing member to the optical fiber structure. I was able to. In addition, since the softening temperature of the synthetic silica glass constituting the optical fiber is about 1300 ° C., the optical fiber array could be fused without any deformation.

On the other hand, the power of excitation light (continuous light, wavelength 977 nm) output from each LD stack as the excitation light source was 120 W on average. Therefore, a total of 1440 W of excitation light was input to the optical fiber structure. At this time, the excitation light from the excitation light source was condensed to an average height of 200 μm and a width of 2.5 mm (1 / e ² ) on the end face of each excitation light guide member. The central wavelength of the excitation light was 977 ± 2 nm at the maximum output. Further, the optical fiber structure including the excitation light source was cooled by a water flow of 20 ° C. As a result, an output laser beam of approximately 1150 W was obtained from the optical device as a laser oscillator. Further, when the beam quality was measured, M2 was about 1.46.

Example 4
The optical device according to Example 4 corresponds to the fourth embodiment described above. Three optical fiber structures of Example 1 were manufactured, and as shown in FIG. 10, these three optical fiber structures were connected in series to connect a plurality of cores included in each optical fiber. Thus, one optical path was obtained. In each optical fiber structure, 20 pumping light introducing members are optically connected to the upper surface of the disk-shaped optical fiber structure at equal intervals in the circumferential direction, and output from each LD stack as a pumping light source. The average power of the excitation light (continuous light) was 60 W. Therefore, a total of 1200 W of pumping light was input to each optical fiber structure, and a total of 3600 W of pumping light was input to the entire three optical fiber structures. As a result, an output laser beam of approximately 2500 W was obtained from the optical device as a laser oscillator. Further, when the beam quality was measured, M2 was about 1.46, which was the same as the case of one optical fiber structure.

(Example 5)
The optical fiber structure and optical device of Example 5 substantially correspond to the first embodiment described above, but four cores containing a laser active material are arranged in parallel in a common clad in the central portion. On the other hand, it is different in that optical fibers separated at both ends are used. The optical fiber structure and optical device of Example 5 were manufactured as follows. First, four optical fiber preforms (core diameter 3 mm, cladding diameter 13 mm, length 500 mm) were produced by the MCVD method. 1.3 wt% Yb ³⁺ ions were added to the core of each optical fiber preform. At this added concentration, the absorption coefficient at a wavelength of 976.5 nm is 900 dB / m to 950 dB / m. The numerical aperture NA of the optical fiber estimated from the refractive index distribution of this optical fiber preform was approximately 0.07.

  Each of these four optical fiber preforms is ground and polished so that the cross-sectional shape is a square with a side length of 8.4 mm, and the four optical fiber preforms are arranged in parallel. The respective side surfaces were fused and connected to each other. At the time of this fusion splicing, unfused portions of 5 mm were periodically formed every 19 mm in the longitudinal direction. The formation of the unfused portion is facilitated by providing a recess having a maximum depth of 0.1 mm over a length of 5 mm at intervals of 19 mm in advance on the side surfaces to be connected to the two optical fiber preforms. .

  The optical fiber preform fused in this way was drawn by a drawing apparatus to produce an optical fiber having a rectangular cross-sectional shape of 0.11 mm × 0.44 mm. At this time, in the portion where the unfused portion of the optical fiber preform was drawn, square optical fibers having a cross-sectional shape of 0.11 mm × 0.11 mm were formed into fibers without being bonded to each other. As a result, the produced optical fibers are fused approximately 110 m, the cross-sectional shape is rectangular and the array type fiber part (fused part) containing four cores, and approximately 30 m separated from each other. The non-fused separation portion having a square cross section that encloses the core of the above was of a periodic separation type in which the core is periodically distributed. The core diameter was about 40 μm.

  The optical fiber manufactured in this way is separated so as to have an approximately 2 m unfused separation part on both sides of the approximately 110 m fusion part, and the four cores are common in the central part (fusion part). An optical fiber that was separated in both ends (unfused separation part) while being arranged in parallel in the clad was obtained. Then, the fused portion of the optical fiber was densely wound around a reel so as to be laminated in a direction perpendicular to the parallel surface of the four cores arranged in parallel to form a disk shape. Further, adjacent clads in this wound state were connected by a heat-resistant optical resin. The refractive index of this optical resin was adjusted within about ± 3% around the refractive index of 1.4585 of the clad glass.

  Next, each of the four end faces in the separated unfused portion drawn out to the inside of the optical fiber structure is polished to a flat surface, and two of these four are used by an optical fiber fuser using discharge heating. The other end surfaces were core-aligned and fusion spliced, and the other two end surfaces were core-aligned and fusion spliced. Further, each of the four end faces in the separated unfused portion drawn out of the optical fiber structure is polished to a flat surface, and two of these four are fused by an optical fiber fuser using discharge heating. The end faces were core aligned and fusion spliced. Each connection loss was 0.1 dB or less. By connecting in this way, the optical fibers constituting the optical fiber structure are connected together. As a result, the output from the core of the optical fiber is 2 of the separated unfused portion drawn from the outside of the optical fiber structure. It was limited to emission from the end face of the location. The optical device at this time is used as an optical amplifier.

  Furthermore, a dielectric multilayer film reflecting mirror having a reflectance of 99.9% (@wavelength 1100 ± 5 nm) is abutted against one end face of the two unconnected cores in the outer separated unfused portion. By connecting, the laser output was limited to one direction. At this time, the end face on the output light extraction side had a reflectance of about 4% of Fresnel reflection. The optical device at this time is used as a laser oscillator.

  Next, 20 excitation light introducing members were optically connected to the upper surface of the disk-shaped optical fiber structure at equal intervals in the circumferential direction. Each excitation light introducing member has a substantially flat plate shape made of synthetic quartz glass, has a cross-sectional shape of a rectangle of 0.45 mm × 2.5 mm, has a length of 80 mm, and totally reflects the excitation light. The angle between the inclined surface and the lower surface for introduction into the optical fiber was 4 degrees. At this time, the same optical resin as that used for the connection between the clads of the optical fiber was used for bonding the excitation light introducing member and the optical fiber.

  As an excitation light source provided corresponding to each excitation light introducing member, an LD stack having four emitter rows was used. Excitation light (wavelength 977 nm) emitted from each emitter was made substantially parallel light with respect to both the fast axis and the slow axis by two collimators, and was incident on the vertical polished end face of the excitation light introducing member by a condenser lens. The excitation light introduced into the excitation light introducing member was introduced into a disk-shaped optical fiber.

  The average power of pumping light (continuous light) output from each LD stack as the pumping light source was 160 W. Therefore, a total of 3200 W of excitation light was input to the optical fiber structure. As a result, an output laser beam of approximately 2600 W was obtained from the optical device as a laser oscillator. Further, when the beam quality was measured, M2 was about 1.46, which was almost the same as that in Example 1.

(Example 6)
The optical fiber structure and the optical device according to Example 6 correspond to the second embodiment described above. Also in Example 6, an optical fiber having two cores was produced in the same manner as in Example 1 described above.

  As shown in FIG. 7, the fused portion of the optical fiber is tightly wound around the cooling member so as to be laminated in a direction perpendicular to the parallel surface of the two parallel cores, and has a cylinder shape. It was. The cooling member used here was made of metal, had a diameter of 130 mm, a height of 150 mm, and had a structure capable of water-cooling the inside. Further, a fluororesin having a refractive index of 1.34 was applied to the side surface of the cooling member to an average thickness of about 5 μm, and a fused portion of an optical fiber was wound on the fluororesin. The width of the rolled cylindrical optical fiber structure was 30 mm. Further, adjacent clads in this wound state were connected by a heat-resistant optical resin.

  Next, each of the two end faces in the separated unfused portion drawn out to one side of the cylinder-shaped optical fiber structure is polished to a flat surface, and these two fibers are obtained by an optical fiber fuser using discharge heating. The end surfaces of the cores were core aligned and fusion spliced. This connection loss was 0.1 dB or less. By connecting in this way, the optical fibers constituting the optical fiber structure are connected together. As a result, the output from the core of the optical fiber is separated from the other side of the optical fiber structure. It was limited to emission from the two end faces. The optical device at this time is used as an optical amplifier.

  Further, the two end faces of the separated unfused portion on the other side are polished to a flat surface in the same manner as the inside, and a dielectric multilayer having a reflectivity of 99.9% (@wavelength 1100 ± 5 nm) is provided on either one end face. The laser output was limited to one direction by abutting and connecting the film reflecting mirror. At this time, the end face on the output light extraction side had a reflectance of about 4% of Fresnel reflection. The optical device at this time is used as a laser oscillator.

  Next, as shown in FIG. 8, six excitation light introducing members were optically connected to the side surface of the cylindrical optical fiber structure at equal intervals in the circumferential direction. Each excitation light introducing member has a substantially flat plate shape made of synthetic quartz glass, has a cross-sectional shape of a rectangle of 0.22 mm × 2.5 mm, a length of 150 mm, and totally reflects the excitation light. The angle between the inclined surface and the lower surface for introduction into the optical fiber was 3 degrees. At this time, the same optical resin as that used for the connection between the clads of the optical fiber was used for bonding the excitation light introducing member and the optical fiber.

  As an excitation light source provided corresponding to each excitation light introducing member, an LD stack having two emitter rows was used. The power of pumping light (continuous light) output from each LD stack was 30 W on average. Therefore, a total of 180 W of excitation light was input to the optical fiber structure. As a result, an output laser beam of about 140 W was obtained from the optical device as a laser oscillator. When the beam quality was measured, M2 was approximately 1.21.

It is the top view and sectional drawing of the optical fiber structure 10 which concern on 1st Embodiment. It is the perspective view and sectional drawing of the optical fiber 11 used in the optical fiber structure 10 which concerns on 1st Embodiment. It is the top view and sectional drawing of 11 A of optical fiber base materials used for manufacture of the optical fiber 11. FIG. 1 is a plan view of an optical device 1 including an optical fiber structure 10 according to a first embodiment. 2 is a plan view and a side view of the excitation light introducing member 13, the optical system 14, and the excitation light source 15. FIG. 2 is a side view of an optical fiber 11, an excitation light introducing member 13, an optical system 14, and an excitation light source 15. FIG. It is the perspective view and sectional drawing of the optical fiber structure 20 which concern on 2nd Embodiment, It is a top view of the optical apparatus 2 containing the optical fiber structure 20 which concerns on 2nd Embodiment. It is the perspective view and sectional drawing of the optical fiber structure 30 which concern on 3rd Embodiment, It is a block diagram of the optical apparatus 4 which concerns on 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1-4 ... Optical apparatus, 10 ... Optical fiber structure, 11 ... Optical fiber, 12 ... Reflection member, 13 ... Excitation light introducing member, 14 ... Optical system, 15 ... Excitation light source, 20 ... Optical fiber structure, 21 ... optical fiber, 22 ... reflection member 23 ... excitation light introducing member, 24 ... optical system 25 ... pumping light source, 29 ... cooling member, 30 ... optical fiber structure, 31 ... optical fiber, 32 ... reflecting member ₄₀ 1 - 40 ₃ ... Optical fiber structure, 42.

Claims (4)

A plurality of cores containing a laser active substance are arranged in parallel on a predetermined surface in a common clad at a central portion, and are provided with optical fibers separated individually at both ends,
At least a part of the central portion of the optical fiber is wound and laminated in a direction perpendicular to the predetermined plane ;
The end surfaces of the cores individually separated at the both end portions of the optical fiber are optically coupled, and the plurality of cores are connected to form one optical path.
An optical fiber structure characterized by that.
  2. The optical fiber structure according to claim 1, wherein a reflection member that reflects light emitted from a laser active material contained in each core of the optical fiber is provided on one end face of the optical path.   A pumping light introducing member for introducing pumping light for exciting a laser active substance contained in each core of the optical fiber into the optical fiber at a laminated portion of the central portion of the optical fiber; The optical fiber structure according to claim 1 or 2. An optical apparatus comprising: the optical fiber structure according to claim 3; and an excitation light source that outputs excitation light to be introduced into an optical fiber included in the optical fiber structure.

Images