JP4242805B2 - Optical fiber pore filling method and optical fiber - Google Patents

Description

  The present invention relates to a method of filling a fine hole of an optical fiber having a fine hole and an optical fiber, and more particularly to a method of filling a fine hole of a photonic crystal fiber (hereinafter referred to as “PCF”) and an optical fiber.

  A solid core, and at least one large-diameter pore that covers the core and extends in the longitudinal direction of the core, and extends in the longitudinal direction of the core to form a photonic crystal structure There is known a PCF including a clad in which a plurality of pores including small pores having a diameter smaller than that of a large pore are formed. Further, the PCF is provided with a hollow core and a plurality of pores that cover the core and extend in the longitudinal direction of the core, and that extend in the longitudinal direction of the core to form a photonic crystal structure An optical fiber (hollow core PCF) is also included.

  Incidentally, in recent years, it has been known to manufacture a polarizer by filling a plurality of pores provided in a clad of PCF having a solid core with a light attenuating substance such as metal. In addition, it is known that a core portion is polarized by filling a plurality of pores with an aluminum or lithium chloride aqueous solution to produce a polarized optical fiber. For example, Patent Document 1 discloses an optical fiber in which some of a plurality of pores of a PCF having a solid core are filled with a light attenuating substance such as copper or nickel. Yes. This optical fiber with pores filled with copper, nickel, etc. can be used as an optical fiber polarizer, and a quartz glass rod as a core, a quartz capillary as a cladding, and a light attenuating rod as an optical attenuating material are desired. It is described that the base material is formed by being bundled so as to be arranged, and the base material is drawn by heating drawing.

  Further, Patent Document 2 discloses a method in which one end of an optical fiber is immersed in a liquid filler and filled by capillary action.

It is also considered to use a PCF in which a core of a hollow core PCF is filled with a laser medium and the core is filled with a laser medium or the like as the laser medium.
JP 2004-67438 A JP 2004-101891 A

  However, when a material whose softening temperature is significantly different from the softening temperature of quartz glass, such as tellurite glass or aluminum, is selected as the material filling the pores of the PCF, the manufacturing method described in Patent Document 1 is used. When an optical fiber polarizer is manufactured, bubbles may be generated in the filling material when the base material is heated and stretched. When this bubble is generated, a portion that cannot be used as an optical fiber polarizer is generated. Therefore, when an optical fiber polarizer is manufactured using this manufacturing method, the manufacturing yield is poor. The softening temperature is a temperature at which the substance becomes soft.

  Moreover, in the manufacturing method described in Patent Document 2, since all the pores are filled with the same filler, the use of PCF after filling may be limited.

  The present invention has been made in view of such a point, and the object of the present invention is to use a PCF that can be used to manufacture a high-performance laser medium, an optical fiber polarizer, a polarization inversion fiber, and the like using PCF as a starting material. It is to provide a method for filling pores.

  The method of filling the pores of the first optical fiber includes a solid core, a core covering the core, extending in the longitudinal direction of the core, and at least one extending in the longitudinal direction of the core. A method for filling pores of an optical fiber comprising a large-diameter pore and a clad in which a plurality of pores including a small-diameter pore smaller in diameter than the large-diameter pore are formed. Sealing the plurality of pores at the end of the optical fiber to form a sealed end portion in which the small-diameter pore is sealed longer than the large-diameter pore in the longitudinal direction of the fiber; In the longitudinal direction of the fiber, only the small-diameter pores are sealed and the large-diameter pores are not sealed, the optical fiber is cut perpendicularly to the fiber axis direction, and the large-diameter fine pores are cut. A large-diameter pore opening step for opening a hole, and the large-diameter pore opening step. Ri including the pores of the apertured the large diameter, and a step of filling the pores of large diameter to fill the large pores filler than the opening formed by the opening.

  The method of filling the pores of the second optical fiber includes a hollow core, a core covering the core, extending in the longitudinal direction of the core, and a plurality of fine fibers extending in the longitudinal direction of the core. A method of filling a pore of an optical fiber comprising a cladding in which a hole is formed, wherein the core and the plurality of pores at an end of the optical fiber are sealed, and the core is arranged in a longitudinal direction of the fiber. A step of forming a sealed end portion in which the plurality of pores are sealed longer than in the longitudinal direction of the fiber, and the optical fiber in a portion where only the plurality of pores are sealed and the core is not sealed Cutting the core perpendicular to the fiber axis direction to open the core, and filling the core opened by the core opening process with the core filler from the opening formed by the opening Core filling process Including the.

  The method of filling the pores of the third optical fiber includes a hollow core, a core covering the core, extending in the longitudinal direction of the core, and at least one extending in the longitudinal direction of the core inside. A method for filling pores of an optical fiber comprising a large-diameter pore and a clad in which a plurality of pores including a small-diameter pore smaller than the large-diameter pore are formed. Sealing the core and the plurality of pores at the end of the optical fiber to form a sealed end portion in which the large-diameter pore is sealed longer than the core in the fiber longitudinal direction; In the longitudinal direction of the fiber, the portion of the optical fiber that is sealed with the large-diameter pore and the small-diameter pore and is not sealed with the core is cut perpendicularly to the fiber axis direction to open the core. Core opening step and the core opening step A core filling step in which the core is filled with a core filler from an opening formed by the opening, and after the core filling step, the small-diameter pores are sealed and the large-diameter pores are sealed. A step of opening the large-diameter pore by cutting the optical fiber in a portion not sealed in a direction perpendicular to the fiber axis direction to open the large-diameter pore; A large-diameter pore filling step of filling the large-diameter pores opened by the opening step with a filler for pores larger in diameter than the opening formed by the opening.

  In addition, a preferable method for filling the pores of the first and third optical fibers is that after the filling step of the large-diameter pores, the small-diameter pores are not sealed in the longitudinal direction of the fiber. The photonic crystal fiber is cut perpendicularly to the fiber axis direction to open the small-diameter pore, and the small-diameter pore is opened by the small-diameter pore opening step. And a step of filling small pores with the small pore filler from the opening.

  In the above method, the small-diameter pore filler may be boron, lithium chloride, or aluminum.

  In the first, second, and third optical fiber filling methods, the plurality of fine holes and the core may be sealed by melting at least one end of the photonic crystal fiber.

  Further, in the first, second, and third optical fiber filling methods, at least one end face of the photonic crystal fiber is immersed in a solution of a pore blocking agent, whereby the plurality of pores and the core May be sealed.

  In the first and third optical fiber filling methods, the large-diameter pores may be provided adjacent to the core and sandwiching the core.

  In the first and third optical fiber pore filling methods, the large-diameter pore filler may be boron, lithium chloride, or aluminum.

  In the second and third optical fiber filling methods, the core filler may be tellurite glass, argon, or xenon.

  In the first and third optical fiber pore filling method, the small-diameter pore filler may be boron, lithium chloride, or aluminum.

  The first optical fiber of the present invention is provided with a solid core, covering the core and extending in the longitudinal direction of the core, and internally having at least one large diameter extending in the longitudinal direction of the core. And a clad in which a plurality of pores including small pores smaller in diameter than the large pores are formed, wherein the large pores and The small-diameter pores are filled with a filler, and the filler filled in the large-diameter pores is different from the filler filled in the small-diameter pores.

  The second optical fiber of the present invention is provided with a hollow core, covering the core, extending in the longitudinal direction of the core, and forming therein a plurality of pores extending in the longitudinal direction of the core An optical fiber comprising a clad, wherein the core, the large-diameter pore and the small-diameter pore are filled with a filler, and the core is filled with the filler And the filler with which the said large diameter pore is filled differs from the filler with which the said small diameter pore is filled, respectively.

  When the method for filling a PCF with a filler according to the present invention is used, a high-performance laser medium, an optical fiber polarizer, a polarization inversion fiber, or the like can be produced using PCF as a starting material. In addition, since pores having different pore sizes can be filled with different fillers, the filler is less than when all the pores of the PCF are filled with the same filler. The application range of filled PCF is expanded.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment.

Embodiment 1 of the Invention
In the first embodiment, a structure of a photonic crystal fiber (hereinafter referred to as “PCF”) 10 and a method for filling the large-diameter pores 12a of the PCF 10 will be described.

  First, the structure of the PCF 10 will be described with reference to FIG.

  As shown in FIG. 1, the PCF 10 includes a solid core 11 made of quartz glass, and a clad 13 that covers the core 11 and extends substantially parallel to the longitudinal direction of the core 11. A pair of large-diameter pores 12a, 12a and a plurality of small-diameter pores 12b, 12b,... Extend in the longitudinal direction and form a photonic crystal structure. The large-diameter pores 12 a and 12 a are provided adjacent to the core 11 and sandwiching the core 11.

  In addition, the manufacturing method of PCF10 is not specifically limited. A PCF 10 may be manufactured by preparing a base material by preparing a quartz glass rod and a plurality of quartz capillaries and bundling them in a close-packed manner, and drawing the base material by heating and stretching. In this case, the quartz glass rod corresponds to the core 11 of the PCF 10, and the quartz capillary corresponds to the large diameter pores 12a, 12a and the small diameter pores 12b, 12b,. Alternatively, a quartz glass rod is prepared, a base material is formed by drilling a plurality of holes in the rod cross section using a drill, and the base material is drawn by heating and stretching to produce the PCF 10 Good. In this case, the substantially central portion in the cross section of the quartz glass rod corresponds to the core 11 of the PCF 10, and the holes opened by the drill are the large-diameter pores 12a, 12a and the small-diameter pores 12b, 12b,. Correspond. Moreover, you may manufacture PCF10 using the other well-known method.

  Next, a method of filling the filler into the large-diameter pores 12a and 12a of the PCF 10 will be described with reference to FIG. 2 is an end view of the PCF 10, and the right side of FIG. 2 is a perspective view of the side surface of the PCF 10. Moreover, the hatching given in FIG. 2 does not represent a cross section, but represents that the large-diameter pores 12a and 12a of the PCF 10 are filled with the large-diameter pore filler.

  First, one fiber end of the PCF 10 is heated and melted. Then, the clad 13 is melted at one fiber end, and the clad 13 is melted to seal the large diameter pores 12a, 12a and the small diameter pores 12b, 12b,. A sealed end is formed. The heat applied to one end of the fiber is conducted to some extent in the fiber longitudinal direction, and the clad 13 at a position slightly away from the one end of the fiber is slightly melted due to the conduction of the heat. Here, the small-diameter pores 12b, 12b,... Are easy to be sealed because they are smaller in diameter than the large-diameter pores 12a, 12a. Therefore, in the portion where the cladding 13 is slightly melted, the small-diameter pores 12b. , 12b,... Therefore, as shown in FIG. 2 (a), by melting one fiber end of the PCF 10, one small diameter pores 12b, 12b, ... Are formed, and only the large-diameter pores 12a, 12a are not sealed. As a result, the large-diameter pores 12a, 12a are formed longer than the small-diameter pores 12b, 12b,. Note that the heat applied to one fiber end does not conduct at all to a region sufficiently away from the one fiber end, so the cladding 13 in that region does not melt.

  Next, a portion 18 shown in FIG. 2 (a) in which only the small diameter pores 12b, 12b,... Are sealed and the large diameter pores 12a, 12a are not sealed is cut perpendicularly to the fiber axis direction. As shown in FIG. 2B, the large-diameter pores 12a and 12a are opened.

  Subsequently, a large-diameter pore filler is injected from the large-diameter pore openings 112a and 112a shown in FIG. 2B, and the large-diameter pores 12a and 12a are used for the large-diameter pores. Fill with filler. For example, when boron is selected as a filler for large-diameter pores, the residual stress of boron is large, so that the stress distribution in the fiber cross section of PCF after filling shows anisotropy. Therefore, the PCF after filling functions as a polarization maintaining PCF. As shown in FIG. 1, since the pair of large-diameter pores 12a and 12a are provided adjacent to the core 11 and sandwiching the core 11, the pair of large-diameter pores 12a and 12a have boron. Although the PCF 10 has polarization maintaining properties even if it is not filled, the polarization plane of propagating light can be stably held by filling the pair of large-diameter pores 12a and 12a with boron. In addition, when aluminum is selected as a filler for large-diameter pores, the light attenuation of aluminum is high and its electrical conductivity is high. Therefore, the PCF after filling is used as a polarizer, a polarization inversion fiber, or a polarizer and a polarization inversion fiber. Function. Furthermore, when a lithium chloride aqueous solution is selected as a filler for large-diameter pores, the conductivity of the lithium chloride aqueous solution is large, so that the PCF after filling functions as a polarization inversion fiber. Here, in the present embodiment, the PCF after filling means PCF in which large-diameter pores are filled with a large-diameter pore filler.

  In addition, the filling method of the filler for large diameter pores is not particularly limited. For example, by preparing a liquid large-diameter pore filler and immersing one fiber end of the PCF 10 in the liquid large-diameter pore filler (capillary phenomenon), the large-diameter pore 12a may be filled with a liquid large-diameter pore filler.

  Alternatively, the large-diameter pores 12a may be filled with the large-diameter pore filler by standing the PCF 10 vertically and flowing a liquid large-diameter pore filler from the fiber end face. This method is preferable compared to the method using the capillary phenomenon described above. This is because the PCF 10 having a long fiber length can fill the large-diameter pores 12a with the large-diameter pore filler in a short time as compared with the case where the capillary phenomenon is used. .

  As described above, in the present embodiment, after the PCF 10 is manufactured, the large-diameter pores 12a and 12a are filled only with the large-diameter pores by using the method of filling the pore filler of the PCF 10 in the present embodiment. Fill with filler. Therefore, unlike the case of using the manufacturing method described in Patent Document 1, the pores of the PCF 10 can be filled with a substance whose softening temperature is significantly different from that of quartz glass. Therefore, bubbles do not exist in the PCF after filling, and therefore a polarizer and a polarization inversion fiber can be manufactured with high yield. Furthermore, unlike the case of using the manufacturing method described in Patent Document 1, the material for the large-diameter pore filler is not limited to a material whose softening temperature is close to the softening temperature of quartz glass. Therefore, the application range of PCF after filling is expanded.

  Further, in the method of filling the PCF 10 pore filler in the present embodiment, when one end of the PCF 10 is heated and melted, as described above, the length sealed by the small-diameter pore and the large-diameter pore is: Different. As a result, only the small-diameter pores 12b, 12b,... Are sealed and the large-diameter pores 12a, 12a are not sealed, and the portion 18 is cut perpendicular to the fiber axis direction. Thus, only the large-diameter pores 12a can be opened. As described above, only a desired pore can be filled with a filler by a very simple method of heating and melting the ends of PCF fibers having different pore sizes. This also expands the application range of PCF after filling.

  In this embodiment, by melting one fiber end of the PCF 10, the small diameter pores 12b, 12b,... Are sealed longer than the large diameter pores 12a, 12a in the longitudinal direction of the fiber. As a result, the large-diameter pores 12a, 12a are formed longer than the small-diameter pores 12b, 12b,..., But the pores are sealed using a pore-sealing agent using capillary action. Thus, the small-diameter pores 12b, 12b,... Can be sealed longer than the large-diameter pores 12a, 12a. The method is shown below.

  First, a liquid pore blocking agent is prepared. Next, one end of the fiber of the PCF 10 is placed in parallel with the bottom of the container containing the pore-sealing agent solution and immersed in the pore-sealing agent solution. Then, the pore blocking agent rises through the inner walls of the large-diameter pores 12a, 12a and the inner walls of the small-diameter pores 12b, 12b,..., Thereby causing the large-diameter pores 12a, 12a and the small-diameter pores 12a, 12a,. The pores 12b, 12b,... Are filled with a pore blocking agent. Here, the smaller the pore diameter is, the longer the pore-sealing agent is filled in the longitudinal direction of the fiber. Therefore, as shown in FIG. 3, the pores 12b, 12b,. The length of the pore-sealing agent to be filled becomes longer than the length of the pore-sealing agent to be filled in the large-diameter pores 12a and 12a. Therefore, the large-diameter pore can be formed longer than the small-diameter pore in the longitudinal direction of the fiber. 3 is an end view of the PCF 10, and the diagram shown on the right side of FIG. 3 is a perspective view of the side surface of the PCF 10. Moreover, the hatching given in FIG. 3 does not represent a cross section, but the pores 12a, 12a and the pores 12b, 12b,... Represents that.

  Furthermore, although the fiber end portion of the PCF 10 is melted in this embodiment, the following method may be used. That is, first, a portion other than the fiber end is melted. Next, the melted portion is cut perpendicular to the fiber axis direction. This gives the same result as melting the fiber end.

  In this embodiment, when the PCF after filling is used as a polarizer or a polarization inversion fiber, the large-diameter pores 12a and 12a are provided adjacent to the core 11 and sandwiching the core 11 therebetween. You don't have to. At least one of the pores forming the photonic crystal structure in the fiber cross section may be a large pore.

<< Embodiment 2 of the Invention >>
The method of filling the PCF pores in the second embodiment is that not only the large-diameter pores 12a of the PCF 10 in the first embodiment but also the small-diameter pores 12b, 12b,. Is different from the PCF pore filling method of the first embodiment. Hereinafter, a method for filling the pores of the PCF in this embodiment will be described with reference to FIGS. 4 is an end view of the PCF 10, and the diagram shown on the right side of FIG. 4 is a perspective view of the side surface of the PCF 10. Moreover, the hatching given in FIG. 4 does not represent a cross section, but represents that the small-diameter pores 12b, 12b,... Of the PCF 10 are filled with the small-diameter pore filler.

  In the method of filling the pores of the PCF 10 in the present embodiment, first, the large-diameter pores 12a and 12a are filled with the large-diameter pore filler. This filling method is the same as the filling method of the pores of the PCF 10 in the first embodiment. After filling the large-diameter pores 12a, 12a with the large-diameter pore filler, the portion 19 where the small-diameter pores 12b, 12b,... Shown in FIG. Cut perpendicularly to the direction to open small-diameter pores 12b, 12b,... As shown in FIG.

  Next, a small-diameter pore filler is injected from the small-diameter pore openings 112b, 112b,... Shown in FIG. 4A, and the small-diameter pore filler is used as the small-diameter pores 12b, 12b. , ... are filled. For example, when aluminum is selected as the small-diameter pore filler, the PCF after filling functions as a polarizer by filling the large-diameter pores 12a and 12a with the large-diameter pore filler, By filling aluminum into the small-diameter pores 12b, 12b,..., It functions as a domain-inverted fiber or a polarizer and domain-inverted fiber. When a lithium chloride aqueous solution is selected as the filler for small diameter pores, the PCF after filling functions as a polarizer by filling the large diameter pores 12a, 12a with the large diameter pore filler. At the same time, the small-diameter pores 12b, 12b,... At this time, the method of filling the small-diameter pore filler into the small-diameter pores 12b, 12b,... Is not limited as described in the first embodiment. In this embodiment, the PCF after filling is a PCF in which large pores are filled with a large pore filler, and small pores are filled with a small pore filler. means.

  As described above, in the method of filling the pore fillers of the PCF 10 in the present embodiment, the large-diameter pores 12a, 12a and the small-diameter pores 12b, 12b,. Therefore, compared to the case of the first embodiment, the usage of the PCF after filling becomes wider.

  In the present embodiment, the pores provided in the cladding 13 are the large-diameter pores 12a, 12a and the small-diameter pores 12b, 12b,... There are two types, but, for example, by providing medium-sized pores, maximum-sized pores, and minimum-sized pores, the number of types of fillers filled in the PCF 10 can be three or more. Thereby, a PCF having a plurality of functions can be manufactured.

<< Embodiment 3 of the Invention >>
In the third embodiment, unlike the first embodiment, the core of the PCF is hollow. Below, the structure of PCF20 and the filling method of the pores of PCF20 are demonstrated.

  First, the structure of the PCF 20 will be described with reference to FIG.

  As shown in FIG. 5, the PCF 20 includes a hollow core 21 and a clad 23 that covers the core 21 and extends substantially parallel to the longitudinal direction of the core 21. In the clad 23, a plurality of pores 22a, 22a,... Having a diameter smaller than that of the core 21 are provided extending in the longitudinal direction of the PCF 20 and forming a photonic crystal structure. The PCF 20 can be manufactured using a known manufacturing method.

  Next, a method of filling the core filler into the core 21 of the PCF 20 will be described with reference to FIG. 6 is an end view of the PCF 20, and the right side of FIG. 6 is a perspective view of the side surface of the PCF 20. Moreover, the hatching given in FIG. 6 does not represent a cross section, but represents that the core 21 of the PCF 20 is filled with the core filler.

  First, one fiber end of the PCF 20 is heated and melted. At this time, since the diameter of the core 21 is larger than the diameter of each pore 22a, by heating and melting one fiber end of the PCF 20 as described in the first embodiment, the core 21 and the plurality of cores 22 The pores 22a, 22a,... Have different sealing lengths. That is, as shown in FIG. 6 (a), a portion 27 where only the pores 22a, 22a,... Are sealed and the core 21 is not sealed is formed in a portion slightly apart from one fiber end. The core 21 is formed longer than the pores 22a, 22a,.

  Next, a portion 27 in which only the pores 22a, 22a,... Shown in FIG. 6 (a) and the core 21 is not sealed is cut perpendicularly to the fiber axis direction and shown in FIG. 6 (b). Thus, the core 21 is opened.

  Subsequently, the core filler is injected from the opening 121 of the core shown in FIG. 6B to fill the core 21 with the core filler. For example, when tellurite glass is selected as the core filler, the PCF after filling functions as a laser medium. When argon is selected as the core filler, the PCF after filling functions as a laser medium for a high-power femtosecond pulse laser. Furthermore, when xenon is selected as the core filler, the PCF after filling functions as a laser medium for a high-power soliton pulse laser. Here, in the present embodiment, the PCF after filling means PCF in which the core is filled with the core filler.

  The method for filling the core 21 with the core filler is not limited. Below, the specific method at the time of selecting tellurite glass as a filler for cores is shown.

  First, an electric furnace that can be heated in the longitudinal direction of the PCF 20 is prepared, and a powder of tellurite glass is put into the electric furnace and melted by heating to be liquefied. Next, a PCF having a hollow core having a diameter of 11.9 μm is prepared, and one end face of the PCF is immersed in liquefied tellurite glass. Thereby, the tellurite glass is filled in the core. Specifically, for example, the temperature of the electric furnace may be raised from room temperature to 800 ° C. over 1.5 hours, and then constant at 800 ° C. for 2 hours, and then naturally cooled.

  In the present embodiment, one end of the PCF 20 is melted to seal the pores 22a, 22a,... Longer than the core 21 in the longitudinal direction of the fiber. The pores 22a, 22a,... May be sealed longer than the core 21 by a method of sealing the pores using a pore-sealing agent using the capillary phenomenon described below.

<< Embodiment 4 of the Invention >>
Unlike the PCF 20 in the third embodiment, the PCF in the fourth embodiment is provided with large-diameter pores and small-diameter pores in the PCF cladding. Hereinafter, the structure of the PCF 30 and the method for filling the pores of the PCF 30 will be described.

  First, the structure of the PCF 30 will be described with reference to FIG.

  As shown in FIG. 7, the PCF 30 includes a hollow core 31 made of quartz glass, and a clad 33 that covers the core 31 and extends substantially parallel to the longitudinal direction of the core 31. In the clad 33, a pair of large-diameter pores 32a, 32a and a plurality of small-diameter pores 32b, 32b,... Extend in the longitudinal direction and form a photonic crystal structure. The large-diameter pores 32 a and 32 a are provided adjacent to the core 31 and sandwiching the core 31. In the cross section of the fiber, the diameter of the core 31 is larger than the diameters of the large pores 32a, 32a and the small pores 32b, 32b,. Moreover, PCF30 can be manufactured using a well-known manufacturing method.

  Next, a method of filling the core filler into the core 31 of the PCF 30 will be described with reference to FIG. 8 is an end view of the PCF 30, and the diagram shown on the right side of FIG. 8 is a perspective view of the side surface of the PCF 30. Further, the hatching applied in FIG. 8 does not represent a cross section, but represents that the core 31 of the PCF 30 is filled with the core filler, and the large-diameter pores 32a and 32a This indicates that the large-diameter pore filler is filled.

  First, one fiber end of the PCF 30 is heated and melted. At this time, the core 31, the large-diameter pores 32a, 32a and the small-diameter pores 32b, 32b,... Are sealed at one end of the fiber to form a sealed end. Since the diameter of the core 31 is larger than the diameters of the large-diameter pores 32a, 32a and the small-diameter pores 32b, 32b,..., As described in the first embodiment, .. Are sealed longest, and the lengths of the large-diameter pores 32a, 32a and the core 31 sealed in this order are shortened. That is, as shown in FIG. 8A, the core 31 is formed to be the longest in the longitudinal direction of the fiber, and the length becomes shorter in the order of the large diameter pores 32a, 32a, the small diameter pores 32b, 32b,. .

  Next, a portion 37 where the large diameter pores 32a and 32a and the small diameter pores 32b, 32b,... And the core 31 are not sealed is cut perpendicularly to the fiber axis direction as shown in FIG. Then, as shown in FIG. 8B, the core 31 is opened.

  Subsequently, tellurite glass is injected from the opening 131 of the core shown in FIG. 8C, and the core 31 is filled with tellurite glass.

  Thereafter, a portion 38 in which the small-diameter pores 32b, 32b,... Are sealed and the large-diameter pores 32a, 32a are not sealed in the longitudinal direction of the fiber shown in FIG. Then, as shown in FIG. 8D, the large-diameter pores 32a and 32a are opened.

  Then, a large-diameter pore filler is injected into the large-diameter pore openings 132a and 132a shown in FIG. 8D, and the large-diameter pores 32a and 32a are filled with the large-diameter pore filler. Fill with agent. For example, when boron is selected as the large-diameter pore filler, as described in the first and third embodiments, the PCF after filling functions as a laser medium by filling the core 31 with the core filler. At the same time, the large diameter pores 32a and 32a are filled with boron to function as a polarizer. When aluminum is selected as the large-diameter pore filler, as described in the first and third embodiments, the PCF after filling functions as a laser medium by filling the core 31 with the core filler. At the same time, the large pores 32a and 32a are filled with aluminum to function as a polarizer, a polarization inversion fiber, or a polarizer and a polarization inversion fiber. When a lithium chloride aqueous solution is selected as the large-diameter pore filler, the PCF after filling functions as a laser medium by filling the core 31 with the core filler, and the large-diameter pores 32a, By filling the lithium chloride aqueous solution into 32a, it also functions as a polarization inversion fiber. Here, in the present embodiment, the PCF after filling means a PCF in which the core is filled with the core filler, and the large pores are filled with the large pore filler.

<< Embodiment 5 of the Invention >>
The PCF pore filling method in the fifth embodiment is not limited to the core 31 and the large-diameter pores 32a, 32a of the PCF 30 in the fourth embodiment, but also the small-diameter pores 32b, 32b,. Is different from the PCF pore filling method of the fourth embodiment. Hereinafter, a description will be given with reference to FIG. 9 is an end view of the PCF 30, and the diagram shown on the right side of FIG. 9 is a perspective view of the side surface of the PCF 30. Further, the hatching applied in FIG. 9 does not represent a cross section, but represents that the small-diameter pores 32b, 32b,... Of the PCF 30 are filled with the small-diameter pore filler.

  In the method of filling the pores of the PCF 30 in the present embodiment, first, the core 31 is filled with the core filler, and then the large-diameter pore 32a is filled with the large-diameter pore filler. These filling methods are the same as those for filling the pores of the PCF 30 in the fourth embodiment. Then, after filling the core 31 and the large-diameter pore 32a with the core filler and the large-diameter pore filler, respectively, the small-diameter pores 32b, 32b, .. Are sealed perpendicularly to the fiber axis direction to open small-diameter pores 32b, 32b,... As shown in FIG.

  Next, a small-diameter pore filler is injected into the small-diameter pore openings 132b, 132b,... Shown in FIG. 9A, and the small-diameter pores 32b, 32b,. Fill with filler. For example, when a material having a lower refractive index than quartz such as resin is selected as the filler for small diameter pores, the refractive index in the core 31 and the large diameter pores 32a, 32a and the small diameter pores 32b, 32b,. The difference from the refractive index can be reduced. Also, the numerical aperture in the fiber cross section of the PCF after filling is smaller than when the small-diameter pores 32b, 32b,... Are not filled with the small-diameter pore filler. As described above, filling the resin or the like into the small-diameter pores 32b, 32b,... Decreases the refractive index variation in the fiber cross section and reduces the numerical aperture in the fiber cross-section. , 32b,..., 32b,..., 32b,. That is, the directivity of the emitted light from the PCF after filling can be improved as compared with the case where the small-diameter pores 32b, 32b,.

  When aluminum is selected as the filler for small diameter pores, the PCF after filling fills the core 31 with the core filler and the large diameter pores 32a and 32a with the large diameter pore filler. By filling, it functions as a laser medium and a polarizer, and also functions as a polarization inversion fiber by filling aluminum into the small-diameter pores 32b, 32b,. When a lithium chloride aqueous solution is selected as the small-diameter pore filler, the PCF after filling fills the core 31 with the core filler and fills the large-diameter pores 32a and 32a with the large-diameter pore. By filling the agent, it functions as a laser medium and a polarizer, and also functions as a polarization inversion fiber by filling the small-diameter pores 32b, 32b,. Here, in this embodiment, the PCF after filling means that the core is filled with the core filler, the large pores are filled with the large pore filler, and the small pores are filled with the small diameter. It means PCF filled with pore filler.

<< Other Embodiments >>
In Embodiments 1 to 5, the optical fiber that fills the pores with the filler is PCF. However, the optical fiber is not limited to PCF. In the case of an optical fiber provided with pores, the pores can be filled with a filler, and the filled optical fiber can be used as a polarizer, a polarization inversion fiber, a laser medium, or the like.

  In Embodiments 1, 2, 4, and 5 described above, boron, aluminum, and an aqueous lithium chloride solution are used as the large-diameter pore filler and the small-diameter pore filler, but the invention is not limited thereto. . In order to use the PCF after filling as a polarization-maintaining PCF, a material having a large residual stress may be selected as a filler for large-diameter pores, and the PCF after filling may be used as a polarizer, a polarization inversion fiber, or a polarizer. In order to use as a polarization inversion fiber, a material having a large optical attenuation and conductivity may be selected as a filler for large-diameter pores, and in order to use the PCF after filling as a polarization inversion fiber, What is necessary is just to select a material with large electroconductivity as a filler for large diameter pores.

  In the said Embodiment 3, 4, 5, although tellurite glass, argon, and xenon were mentioned as a filler for cores, it is not limited to these.

  As described above, the present invention is useful when a PCF pore is filled with a filler, particularly when a polarizer, a polarization inversion fiber, a laser medium, or the like is manufactured.

1 is a diagram illustrating a structure of a PCF 10 according to a first embodiment. It is a figure which shows the filling method of the filler to the large diameter pore 12a of PCF10 concerning Embodiment 1. FIG. FIG. 6 is a diagram showing another example of a filling method of the filler into the large-diameter pores 12a of the PCF 10 in the first embodiment. 6 is a diagram illustrating a filling method of a filler into large-diameter pores 12a of PCF 10 in Embodiment 2. FIG. It is a figure which shows the structure of PCF20 in Embodiment 3. FIG. 6 is a diagram illustrating a method of filling a filler into a core 21 of a PCF 20 in a third embodiment. FIG. It is a figure which shows the structure of PCF30 in Embodiment 4. FIG. It is a figure which shows the filling method of the filler to the core 31 of PCF30 in Embodiment 4, and the large diameter pore 32a. It is a figure which shows the filling method of the filler to the small diameter pore 32b of PCF30 in Embodiment 5. FIG.

Explanation of symbols

10, 20, 30 PCF
11, 21, 31 Cores 12a, 32a Large diameter pores 12b, 32b Small diameter pores 13, 23, 33 Cladding 22a Fine holes 112a, 132a Large diameter pore openings 112b, 132b Small diameter pore openings Part 121 core opening 122a pore opening

Claims (14)

A solid core, covering the core and extending in the longitudinal direction of the core; and at least one large-diameter pore extending in the longitudinal direction of the core and the large-diameter pore A method of filling a pore of an optical fiber comprising a cladding in which a plurality of pores including a small-diameter pore having a smaller diameter is formed,
Sealing the plurality of pores at the end of the optical fiber to form a sealed end portion in which the small-diameter pore is sealed longer than the large-diameter pore in the longitudinal direction of the fiber;
In the longitudinal direction of the fiber, only the small-diameter pore is sealed and the large-diameter pore is not sealed, the optical fiber is cut perpendicularly to the fiber axial direction, and the large-diameter pore Opening process of large-diameter pores for opening
A large-diameter pore filling step of filling the large-diameter pore opened by the large-diameter pore opening step with a filler for pores larger in diameter than the opening formed by the opening; A method for filling pores of an optical fiber. A hollow core, covering the core and extending in the longitudinal direction of the core, and a plurality of pores extending in the longitudinal direction of the core and having a smaller diameter than the core are formed therein A method of filling pores in an optical fiber comprising a cladding,
Sealing the core and the plurality of pores at the end of the optical fiber, and forming a sealed end portion in which the plurality of pores are sealed longer than the core in the longitudinal direction of the fiber;
A core opening step of opening the core by cutting the optical fiber perpendicular to the fiber axis direction in the longitudinal direction of the fiber, in which only the plurality of pores are sealed and the core is not sealed; ,
A core filling step of filling the core opened by the core opening step with a core filler from an opening formed by the opening. A hollow core, covering the core, extending in the longitudinal direction of the core, and at least one large-diameter pore extending in the longitudinal direction of the core and having a smaller diameter than the core ; A method for filling pores of an optical fiber comprising a clad in which a plurality of pores including small pores smaller in diameter than the large pores are formed,
Sealing the core and the plurality of pores at the end of the optical fiber, and forming a sealed end portion in which the large-diameter pore is sealed longer than the core in the fiber longitudinal direction;
In the longitudinal direction of the fiber, the portion of the optical fiber that is sealed with the large-diameter pore and the small-diameter pore and is not sealed with the core is cut perpendicularly to the fiber axis direction to open the core. An opening process of the core to be made,
A core filling step of filling the core opened by the core opening step with a core filler from an opening formed by the opening;
After the core filling step, the portion of the optical fiber that is sealed with the small-diameter pore and is not sealed with the large-diameter pore is cut perpendicularly to the fiber axis direction, Opening process of large-diameter pores for opening the pores;
A large-diameter pore filling step of filling the large-diameter pore opened by the large-diameter pore opening step with a filler for pores larger in diameter than the opening formed by the opening; A method for filling pores in an optical fiber. A method for filling pores of an optical fiber according to claim 1 or 3,
Further, after the filling step of the large-diameter pore, the portion of the optical fiber where the small-diameter pore is not sealed in the longitudinal direction of the fiber is cut perpendicularly to the fiber axial direction, Opening process of small-diameter pores for opening the pores;
A small-diameter pore filling step of filling the small-diameter pore opened by the small-diameter pore opening step with a small-diameter pore filler from an opening formed by the opening. Method for filling pores. The method of filling a pore of an optical fiber according to claim 1 ,
At least one of the by melting the end, a method of filling the pores of the optical fiber to seal the plurality of pores of said optical fiber. The method for filling pores of an optical fiber according to claim 2 or 3,
A method for filling pores of an optical fiber, which seals the plurality of pores and the core by melting at least one end of the optical fiber. The method of filling a pore of an optical fiber according to claim 1 ,
At least one of the by the end face is immersed in a solution of the pore blocking agent, the method of filling the pores of the optical fiber to seal the plurality of pores of said optical fiber. The method for filling pores of an optical fiber according to claim 2 or 3,
A method for filling pores of an optical fiber that seals the plurality of pores and the core by immersing at least one end face of the optical fiber in a solution of a pore-sealing agent. The method for filling pores of an optical fiber according to claim 1 or 3,
The large-diameter pore is a method for filling pores of an optical fiber provided adjacent to the core and sandwiching the core. The method for filling pores of an optical fiber according to claim 1 or 3,
The large-diameter pore filler is a method for filling pores of an optical fiber, which is boron, lithium chloride or aluminum. The method for filling pores of an optical fiber according to claim 2 or 3 ,
The core filler is a method for filling pores of an optical fiber, which is tellurite glass, argon or xenon. The method for filling pores of an optical fiber according to claim 4,
The small diameter pore filler is a method for filling pores of an optical fiber, wherein the filler is boron, lithium chloride or aluminum. A solid core, covering the core and extending in the longitudinal direction of the core; and at least one large-diameter pore extending in the longitudinal direction of the core and the large-diameter pore An optical fiber comprising a clad in which a plurality of pores including a small-diameter pore having a smaller diameter is formed,
Wherein the pores of large diameter, boron, lithium or aluminum chloride is filled,
An optical fiber in which the small-diameter pores are filled with a material different from the material filled in the large-diameter pores among boron, lithium chloride, and aluminum . A hollow core and at least one large-diameter pore that covers the core and extends in the longitudinal direction of the core, and that extends in the longitudinal direction of the core and has a diameter smaller than that of the core; An optical fiber comprising a clad having a plurality of pores including small pores having a smaller diameter than the large pores ,
The said core, tellurite glass, argon or xenon is filled,
The large-diameter pores are filled with boron, lithium chloride or aluminum,
An optical fiber in which the small-diameter pores are filled with a material different from the material filled in the large-diameter pores among boron, lithium chloride, and aluminum .

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