JP2008009067A - Optical waveguide structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To guide light suitably through a photonic crystal fiber (PCF) composed of a large diameter part and a small diameter part, by assembling such PCF using an appropriate means or member and thereby making proper connection possible between an optical fiber and other optical waveguide components. <P>SOLUTION: As an optical waveguide structure 1, on the inner peripheral side of a sleeve 2 with the center axis running along the optical waveguide direction, there is fixed the PCF 3 having a large diameter part 3a in one end of the optical waveguide direction and a small diameter part 3b in the other end. When necessary, with the inner peripheral face 2a of the sleeve 2 as a reference, the large diameter part 3a of the PCF 3 is fixedly positioned while an optical fiber 5 or the like is connected to the small diameter part 3b of the PCF 3. In addition, on the inner periphery of the sleeve 2, a support 4 is fixed in which an internal cavity 4a is formed as a reference for positioning the optical fiber 5 or the like, and also the small diameter part 3b of the PCF 3 is fixedly positioned with the internal cavity 4a of the support 4 as the reference, wherein the optical fiber 5 or the like is connected to the small diameter part 3b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical waveguide structure, and more particularly to an optical waveguide structure configured using a photonic crystal fiber in which one side in the optical waveguide direction is a large diameter portion and the other side is a small diameter portion.

  As is well known, a photonic crystal fiber (hereinafter, also simply referred to as “PCF”) has a waveguide core at the center of the fiber, and a plurality of holes are formed with regularity, for example, in a honeycomb shape around the core. This is an optical waveguide member (see Patent Document 1 below). This PCF has a large waveguide core and can guide light in a single mode as compared with an optical fiber generally used for optical communication applications. Even if an extreme bending such as a bending occurs. It has various advantages such as low optical transmission loss.

  When the core diameter of the PCF is made larger than that of the above-mentioned optical fiber that is generally used, when the light is guided from the PCF to the optical fiber or from the optical fiber to the PCF, it is appropriate. And in order to guide accurately, it is requested | required that the diameter in the connection edge part of both should make it equivalent or respond | correspond. Thus, for example, according to the following Patent Document 2, it is disclosed that one end side of a PCF is heated and stretched so that the core diameter of the end portion is made small, and the diameters of the small diameter portion and the optical fiber are matched. Yes.

Special Table 2002-537575 JP 2004-279745 A

  By the way, the core diameter and fiber diameter of the PCF and the ratio thereof are generally set arbitrarily, and may be set appropriately according to the application, but under existing applications. The maximum fiber diameter (fiber diameter of the large diameter portion) of the PCF having the small diameter portion described above is about 0.125 mm. Therefore, as for the PCF having a large-diameter portion greatly deviated from this numerical value (0.125 mm) and a small-diameter portion connected to the large-diameter portion, the actual situation is that no application or usage mode has been found.

  And in relation to such a situation, what kind of assembly structure is needed to produce the above-mentioned optical waveguide structure for optical communication using a PCF having a large diameter portion and a small diameter portion as a constituent element. The problem arises as to whether it is optimal. That is, this type of PCF is not a columnar body having the same diameter along the axial direction, but has a shape that is reduced in diameter and extends from the large diameter portion to the small diameter portion. Therefore, an important and fundamental problem arises that if this type of PCF is connected to an optical fiber or other optical waveguide component by any means or using any member, an appropriate light can be guided.

  In view of the above circumstances, the present invention is to properly connect an optical fiber or other optical waveguide component by assembling a PCF having a large diameter portion and a small diameter portion using an appropriate means or member. It is a technical problem to enable light to be suitably guided through this type of PCF.

  The optical waveguide structure according to the present invention, created to solve the above technical problem, has a central axis on the inner peripheral side of the sleeve along the optical waveguide direction, one side in the optical waveguide direction being a large diameter portion, and the other It is characterized by fixing a photonic crystal fiber having a small diameter side. In this case, the end surface of the large diameter portion of the photonic crystal fiber is preferably a flat surface or a convex surface.

  According to such a configuration, a PCF having a large diameter portion and a small diameter portion (for example, a PCF having a shape from the large diameter portion to the small diameter portion while the outer peripheral surface thereof is reduced in diameter) is formed on the inner periphery of the sleeve. The optical waveguide direction of the PCF is along the axial direction of the sleeve. As a result, this type of PCF can be appropriately incorporated in the sleeve, and the optical fiber and other optical waveguide components can be properly connected to the PCF. That is, by incorporating the PCF in the sleeve in the above-described manner, the sleeve can be effectively used, for example, the optical fiber can be fixed in a state of being aligned with the central axis of the sleeve, and the optical fiber of the optical fiber can be fixed. It is possible to connect the tip end portion with the small diameter portion of the PCF accurately matched. In other words, if the sleeve is used effectively and the PCF, optical fiber, etc. are positioned, these connections can be made accurately and easily, and the assembly is performed properly and the operations required for the assembly are performed. Can also benefit from being simplified. In this case, since the core portion in the large diameter portion of the PCF has a wide area, when an optical signal or a light beam is transmitted / received (transmitted / received) through this large diameter portion, the light flux is particularly received. Even if the position is slightly shifted, it can be received without any problem. And this received light beam is appropriately condensed by the small diameter part of PCF. In addition, you may arrange | position the support body which consists of capillaries etc. between a sleeve and a large diameter part as needed.

  In such a basic configuration, the optical fiber or other optical waveguide element is connected to the small-diameter portion of the photonic crystal fiber while being positioned and fixed at the large-diameter portion of the photonic crystal fiber with reference to the inner peripheral surface of the sleeve. Thereby, an optical waveguide structure can be formed. Here, the above-mentioned “connection” means not only the case of being connected in physical contact but also the case of being optically connected even if it is physically non-contact. (The same applies hereinafter).

  In this way, the positioning and fixing of the large diameter portion of the PCF is performed with reference to the inner peripheral surface of the sleeve, so the core portion of the large diameter portion of the PCF is accurately aligned with the central axis of the sleeve. State. Therefore, it is possible to accurately transmit and receive the light flux to and from the large-diameter core portion of the PCF, and a wide area in the large-diameter core portion is accurately positioned, so that an optical signal can be transmitted and received. Etc. is extremely advantageous in properly performing the process through the large diameter portion of the PCF. Since the optical fiber or the like is connected to the small diameter portion of the PCF, for example, an optical signal received through the large diameter portion of the PCF is condensed at the small diameter portion and accurately guided to the optical fiber or the like. The With such a configuration, it is sufficient to position and fix the large-diameter portions of the PCF, and the work efficiency at the time of manufacture and assembly is improved. However, the small diameter portion of the PCF may not be properly positioned, but is preferably positioned by a support such as a capillary.

  The optical waveguide structure having such a configuration can be used as an optical signal transmitter or a part thereof.

  In this way, when the above optical waveguide structure is used as, for example, an optical signal transmitter (or a part thereof), the optical signal is received at an accurate position in a wide area in the large diameter portion of the PCF. Thus, there is an advantage that light can be accurately guided to an optical fiber or the like after being condensed at the small diameter portion.

  On the other hand, in the basic configuration in which the photonic crystal fiber is fixed to the inner peripheral side of the sleeve as described above, the inner hole that serves as a positioning reference for the optical fiber and other optical waveguide elements is formed on the inner periphery of the sleeve. An optical waveguide structure by fixing the body, positioning and fixing the small diameter portion of the photonic crystal fiber with reference to the inner hole of the support, and connecting an optical fiber or other optical waveguide element to the small diameter portion Can be formed.

  In this way, the positioning and fixing of the small diameter portion of the PCF is performed with reference to the inner hole of the support fixed to the inner periphery of the sleeve, so that the optical fiber and other optical waveguide elements and the PCF are mutually connected. It becomes possible to exchange optical signals very accurately. That is, since the optical fiber or the like is configured to be connected to the small diameter portion of the PCF, for example, the core diameter of the optical fiber and the core diameter of the small diameter portion of the PCF are the same or correspond to each other in the connection portion in the sleeve. It can be. In addition, the inner hole of the support in the sleeve serves as a positioning reference for an optical fiber or the like. Therefore, if the small diameter portion of the PCF is positioned and fixed with reference to the inner hole of the support in the sleeve, the core portion of the small diameter portion of the PCF and the core portion of the optical fiber or the like can be accurately matched. Thus, the optical signal incident from the large diameter portion of the PCF can be condensed at the small diameter portion and accurately guided to the optical fiber or the like. With such a configuration, it is sufficient to properly position and fix the small diameter portion of the PCF, and the work efficiency at the time of manufacture and assembly is improved. However, the large-diameter portion of the PCF may not be properly positioned, but is preferably positioned.

  An optical waveguide structure having such a configuration can also be used as an optical signal transmitter or a part thereof.

  Further, in this configuration in which the large diameter portion of the photonic crystal fiber is positioned and fixed with reference to the inner peripheral surface of the sleeve, a pair of photonic crystal fibers is provided, and each large diameter portion of the pair of photonic crystal fibers is provided. It is also possible to dispose them facing each other.

  In this way, since the large-diameter portion of the pair of PCFs is positioned and fixed with reference to the inner peripheral surface of the sleeve, the large-diameter portion of one PCF and the large-diameter portion of the other PCF are mutually fixed. It is possible to transmit and receive optical signals with high accuracy. That is, in the case of an optical waveguide structure that is required to transmit and receive an optical signal accurately between opposing large-diameter portions of a pair of PCFs, the large-diameter portions of those PCFs have the same surface ( Since the positioning is fixed with reference to the inner peripheral surface of the sleeve, the relative positional relationship between the large-diameter portions becomes accurate, and the delivery of optical signals between each other is accurate and reliable.

  Thus, the optical waveguide structure formed by arranging a pair of PCFs on the inner peripheral side of the sleeve can be used as a collimator or a part thereof.

  In this way, collimated light is properly transmitted and received in the gaps between the opposing large-diameter portions that are accurately positioned with reference to the inner peripheral surface of the sleeve in the pair of PCFs. The collimator can be obtained. Note that a filter, an optical isolator, or the like is interposed between the large-diameter portions of the pair of PCFs as necessary.

  When the optical waveguide structure is used as, for example, a collimator (or a part thereof), even if the position of the optical signal is slightly shifted when receiving the optical signal in a wide area in the large diameter portion of the PCF, Since the small-diameter portion is accurately positioned, the optical signal is properly collected at the small-diameter portion, so that there is an advantage that the optical fiber is guided reliably and accurately without causing a waveguide loss or the like. .

  In all the optical waveguide structures described above, the diameter of the large diameter portion of the photonic crystal fiber is 0.5 to 2.5 mm, and the diameter of the small diameter portion is 0.05 to 0.25 mm. Is preferred.

  In this way, as the PCF having the configuration having the large-diameter portion and the small-diameter portion, the above-described uses or use modes have been found, and therefore the diameter (fiber diameter) and the core diameter of the large-diameter portion have been conventionally The optical signal can be transmitted and received in a wide area. Further, if the diameter (fiber diameter) of the small diameter portion of the PCF is within the above numerical range, the diameter of the small diameter portion and the diameter of the optical fiber can be made the same, and appropriate optical waveguide can be performed. Become.

  In all the optical waveguide structures described above, the optical fiber may be PC-connected to the end of the small-diameter portion of the photonic crystal fiber, or the optical fiber may be fused.

  In this way, particularly by making the diameter of the small diameter portion of the PCF the same as the diameter of the optical fiber as described above, the connection portion between them can be made the best mode.

  Furthermore, in all the optical waveguide structures described above, the photonic crystal fiber can be formed by heating and stretching.

  In this way, it is possible to easily manufacture a PCF having a large diameter portion larger than the conventional one and a small diameter portion having the same diameter as that of the optical fiber, as described above, by using a method called heat stretching.

  In all the above optical waveguide structures, for example, as shown in FIG. 8, the outer peripheral surface of the photonic crystal fiber is covered with a covering portion, and the outer peripheral surface of the covering portion is changed from the large diameter portion side to the small diameter portion side. You may comprise so that a diameter may become small continuously toward it.

  In order to achieve such a configuration, it is possible to adopt a method by heat stretching, but other methods, for example, applying glass or resin in a softened state to the outer peripheral surface of the PCF, or utilizing molding Also good. According to such a configuration, since the diameter of the end portion on the small diameter side can be made larger than the core diameter, the advantage that the connection with the optical fiber or the like can be performed satisfactorily by PC connection or the like is enjoyed. Can do.

  Furthermore, in all the optical waveguide structures described above, for example, as shown in FIG. 9, the outer peripheral surface of the photonic crystal fiber may be covered with a covering portion to form a columnar body.

  Since the method for forming such a configuration and the advantages thereof are the same as in the case where the covering portion described above is formed, the description thereof is omitted for convenience.

  As described above, according to the present invention, the PCF having the large diameter portion and the small diameter portion is fixed to the inner peripheral side of the sleeve, and the optical waveguide direction of the PCF is along the axial direction of the sleeve. It can be in a state of being properly incorporated in the sleeve, and can be properly connected to an optical fiber or other optical waveguide component. Therefore, it is possible to enjoy the advantages that the assembly is properly performed for this type of PCF and the work required for the assembly is simplified.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 illustrates an optical waveguide structure according to the first embodiment of the present invention, specifically, an optical waveguide structure used as a transmitter or a collimator for optical communication. As shown in the figure, this optical waveguide structure 1 has a central axis X on the inner peripheral side of the sleeve 2 along the optical waveguide direction, one side in the optical waveguide direction being a large diameter portion 3a and the other side being a small diameter portion 3b. The PCF 3 is fixed. In this case, the sleeve 2 is preferably made of glass or ceramic, but can also be made of resin, metal or the like.

  PCF3 is a glass molded body formed by heat stretching, and as shown in FIG. 2, a core portion 3x is formed on the central axis X, and a plurality of holes 3y are regularly arranged in a honeycomb shape around the core portion 3x. It is formed with sex. The diameter (fiber diameter) of the large diameter portion 3a of the PCF 3 is 0.5 to 2.5 mm (specifically, 1 mm, 1.25 mm, 1.8 mm, 2.5 mm), and the small diameter thereof. The diameter (fiber diameter) of the portion 3b is 0.05 to 0.25 mm (specifically, 0.08 mm and 0.125 mm). In the illustrated example, the end surface 3A of the large-diameter portion 3a is flat, but the end surface 3A of the large-diameter portion 3a is convex in consideration of the advantage of transmitting and receiving optical signals. Is preferred.

  Further, as shown in FIG. 1, the large diameter portion 3 a of the PCF 3 is positioned and fixed with reference to the inner peripheral surface 2 a of the sleeve 2. That is, the large-diameter portion 3a of the PCF 3 is positioned and fixed in a state of being closely fitted to the inner peripheral surface 2a of the sleeve 2, whereby the center axis X of the sleeve 2 and the center of the large-diameter portion 3a of the PCF 3 ( The center of the core portion 3x). The end portion 5c of the optical fiber 5 is connected to the end portion 3c of the small diameter portion 3b of the PCF 3 by PC connection or fusion connection. Therefore, the core portion 3x in the end surface 3A of the large diameter portion 3a of the PCF 3 is positioned on the central axis X of the sleeve 2 with high accuracy.

  In a transmitter or collimator that requires that only the large-diameter portion 3a of the PCF 3 is accurately positioned, accurate positioning or fixing to the sleeve 2 is not necessarily required even for the small-diameter portion 3b.

  In this embodiment, the small diameter portion 3b of the PCF 3 is fixedly supported on the sleeve 2 as shown below. That is, as shown in FIG. 1, a support body (glass capillary, ceramic support body, etc.) 4 having an inner hole 4a at the center (on the center axis X) is fixed to the inner periphery of the sleeve 2. The inner hole 4 a of the support 4 is configured to serve as a positioning reference for the optical fiber 5. Specifically, for example, when the optical fiber 5 is inserted and fixed to a ferrule (not shown) and the ferrule is fitted to the inner periphery of the sleeve 2, the center of the optical fiber 5 and the inner hole 4 a of the support 4 are formed. The center is set so as to be arranged on the same axis.

  In this case, the small diameter portion 3 b of the PCF 3 is positioned and fixed with reference to the inner hole 4 a of the support 4. That is, in this embodiment, the small-diameter portion 3b of the PCF 3 is closely fitted in the inner hole 4a of the support body 4, so that the small-diameter portion 3b of the PCF 3 is accurately fixed (highly accurate) with reference to the inner hole 4a. Has been. Therefore, the core portion at the end surface of the small diameter portion 3 b of the PCF 3 is positioned on the central axis X of the sleeve 2 with high accuracy. When the optical fiber 5 is fixed while being inserted on the central axis of the ferrule, the ferrule comes into contact with the end surface of the support 4 while being fitted to the inner periphery of the sleeve 2. .

  In a transmitter or collimator that requires that only the small-diameter portion 3b of the PCF 3 be accurately positioned, accurate positioning or fixing to the sleeve 2 is not necessarily required even for the large-diameter portion 3a as shown. Absent.

  The sleeve 2 does not have to be a single one as described above. For example, as shown in FIG. 3, the first sleeve 2A to which the support 4 for positioning the small diameter portion 3b of the PCF 3 is fixed; It may be constituted by two (or three or more) second sleeves 2B that are fitted and fixed so as to cover the distal end portion of the first sleeve 2A, and in which the large diameter portion 3a of the PCF 3 is built. In this case, various variations are possible, for example, the first sleeve 2A is made of glass or ceramic, while the second sleeve 2B is made of metal or the like.

  Further, the position of the connecting portion between the small diameter portion 3b of the PCF 3 and the optical fiber 5 is not limited to the above position. For example, as shown in FIG. 3, the optical fiber 5 is provided in the inner hole 4a of the support 4. The end face 3c of the small diameter portion 3b and the end face 5c of the optical fiber 5 may be connected in the vicinity of the end face on the PCF 3 side of the support 4 by inserting and fixing.

  Further, the support 4 need not hold only the portion having the same diameter in the axial direction as the small diameter portion 3b of the PCF 3 as described above. For example, as shown in FIG. 4, the small diameter portion 3b of the PCF 3 is supported. The support body 4 may also be held including the tapered portion 3d that gradually decreases in the axial direction.

  According to the optical waveguide structure 1 having the above configuration, the PCF 3 having a complicated shape from the large diameter portion 3a to the small diameter portion 3b while the outer peripheral surface is curved is formed on the inner peripheral surface a of the sleeve 2. Since the optical waveguide direction of the PCF 3 is along the axial direction of the sleeve 2, the PCF 3 is incorporated in the sleeve 2 in an appropriate state, and can be properly connected to the optical fiber 5. It will be. In other words, it is possible to fix the PCF 3 and the optical fiber 5 in an appropriate state with respect to the central axis X of the sleeve 2 by incorporating the PCF 3 by effectively using the sleeve 2. As a result, the connection between the PCF 3 and the optical fiber 5 (and other optical waveguide elements) connected to the PCF 3 can be performed accurately and easily, the assembly is performed properly, and the work required for the assembly is simplified. You can enjoy the advantage that

  When the optical waveguide structure 1 having the above-described configuration is accurately positioned only in the large-diameter portion 3a of the PCF 3, the core portion of the large-diameter portion 3a of the PCF 3 is used as the center of the sleeve 2. Assume that the axis X is accurately aligned. This makes it possible to accurately transmit and receive optical signals to and from the core portion of the large-diameter portion 3a of the PCF 3, and to effectively utilize the fact that a wide area in the core portion of the large-diameter portion 3a is accurately positioned. Thus, transmission / reception of optical signals and the like can be appropriately performed through the large-diameter portion 3a of the PCF 3. Since the optical fiber 5 is connected to the small diameter portion 3b of the PCF 3, for example, an optical signal received through the large diameter portion 3a of the PCF 3 is condensed by the small diameter portion 3b and accurately guided to the optical fiber 5. In addition, the light incident on the PCF 3 from the optical fiber 5 through the small diameter portion 3b is accurately transmitted as collimator light from the large diameter portion 3a. Even if the optical characteristics vary depending on the PCF3, when the optical signal reaches the small diameter portion 3b from the large diameter portion 3a side of the PCF3, the core diameter is small and the positioning is accurately performed. Therefore, the probability of being adversely affected by the above-described variation is reduced.

  As a specific example of use in this case, as shown in FIG. 5, the first sleeve 2C and the second sleeve 2D are arranged coaxially apart from each other, and the inner peripheral surface 2Ca of the two sleeves 2C, 2D. With respect to 2Da, the large diameter portions 3a of the two PCFs 3 are respectively positioned and fixed. Then, an optical component 8 made of a filter or an optical isolator is interposed in the gap 2Y between the first sleeve 2C and the second sleeve 2D. According to such a configuration, since the large diameter portions 3a of the two PCFs 3 are relatively accurately positioned, collimator light accurately transmitted from the large diameter portion 3a of one PCF 3 is the optical component 8. Then, the light is accurately received by the large diameter portion 3a of the other PCF3. Accordingly, it is difficult to cause an undue waveguide loss due to a deviation in the position of the large-diameter portion 3a of the PCF 3, and an optical waveguide device that is a combination of a high-performance transmitter and receiver (similar to a collimator described later). Equipment).

  On the other hand, when only the small-diameter portion 3a of the PCF 3 is accurately positioned in the optical waveguide structure 1 having the above-described configuration, the inner hole 4a of the support body 4 fixed to the inner periphery of the sleeve 2 is used. Is used for positioning and fixing the small diameter portion 3b of the PCF 3, and the core portion of the small diameter portion 3b of the PCF 3 and the core portion of the optical fiber 5 are accurately matched. Thereby, the optical signal incident from the large diameter portion 3a of the PCF 3 is condensed by the small diameter portion 3b and accurately guided to the optical fiber 5. In this case, since the core portion of the large diameter portion 3a of the PCF 3 has a wide area, even if the optical signal (light beam) incident through the large diameter portion 3a is slightly displaced, the optical signal is satisfactorily obtained. In addition, the optical signal is collected by the small diameter portion 3 b of the PCF 3 and accurately guided to the optical fiber 5.

  As a specific example of use in this case, as shown in FIG. 6, a ferrule 7 with an optical fiber 5 inserted and fixed is fitted on the inner peripheral side of the sleeve 2, and connected to one axial end side of the sleeve 2. The light source 6 is disposed in the holder 9 and the PCF 3 is interposed between the ferrule 7 and the light source 6. According to such a configuration, when the light from the light source 6 is received by the PCF 3, the light is received by the wide core portion of the large-diameter portion 3 a of the PCF 3, so that the light flux from the light source 6 is slightly shifted. Regardless of this, light can be received without hindrance. The light received by the large diameter portion 3a of the PCF 3 causes an optical waveguide loss or the like in the optical fiber 5 inserted and fixed to the ferrule 7 in the sleeve 2 from the small diameter portion 3b of the PCF 3 accurately positioned and fixed. Propagation properly without. This eliminates the need for a conventionally used lens. Of course, the lens may be fixed to the holder 9 and disposed between the PCF 3 and the light source 6.

  FIG. 7 illustrates an optical waveguide structure according to the second embodiment of the present invention, specifically, an optical waveguide structure used as a collimator for optical communication. As shown in the figure, the optical waveguide structure 1 includes a pair of the same structure as the PCF 3 described above, and a single large diameter portion 3a of the pair of PCFs 3 is separated and opposed to each other. It is arranged on the inner peripheral side of the sleeve 2. The large diameter portions 3a of the PCFs 3 are positioned and fixed with reference to the inner peripheral surface 2a of the sleeve 2. That is, these large diameter portions 3a are positioned and fixed with high accuracy in a state where the large diameter portions 3a are properly fitted to the inner peripheral surface 2a of the sleeve 2. In addition, an optical component 8 made of a filter or an optical isolator is interposed in the gap 2X between the large diameter portions 3a, and an optical fiber or other optical waveguide element ( For example, a three-dimensional photonic crystal or PLC is connected (not shown). In the optical waveguide structure 1 according to the second embodiment, the same reference numerals are used for the same constituent elements as those of the optical waveguide structure 1 according to the first embodiment, and the detailed description thereof is omitted. .

  According to the optical waveguide structure 1 according to the second embodiment, collimated light transmitted from the large-diameter portion 3a of one PCF 3 is received by the large-diameter portion 3a of the other PCF 3, Since the large-diameter portion 3a is accurately positioned relative to each other, the collimated light is properly transmitted and received. That is, since the core part in the large diameter part 3a of one PCF 3 and the core part in the large diameter part 3a of the other PCF 3 are arranged to face each other with an accurate posture and an accurate radial position, both cores Collimated light is transmitted and received properly between the parts. The small diameter portion 3b connected to the large diameter portion 3a of one PCF 3 and the small diameter portion 3b connected to the large diameter portion 3a of the other PCF 3 do not have to be positioned in the same manner as the large diameter portion 3a. May be positioned equally.

  In the above embodiment, the outer peripheral surface of the PCF 3 is a bare surface (non-covered surface). For example, as shown in FIG. 8, the outer peripheral surface of the PCF 3 is covered with a covering portion 10 made of resin, glass, or the like. The outer peripheral surface of the covering portion 10 may be formed so that the diameter continuously decreases from the large diameter portion 3a side toward the small diameter portion 3b side. The maximum outer diameter of the covering portion 10 is the same as or smaller than the maximum outer diameter (end portion diameter) of the large diameter portion 3a of the PCF 3, and the covering portion extends to the end of the small diameter portion 3b of the PCF 3. 10 is in a covered state. And PCF3 of such a structure is accommodated in the inside of a sleeve so that it may become the aspect similar to PCF3 shown in FIG.1 and FIGS.

  Further, as shown in FIG. 9, for example, the outer peripheral surface of the PCF 3 is covered with a covering portion 11 made of resin, glass, or the like, and the covering portion 11 is formed so as to form a columnar body (for example, a cylindrical shape). Good. Also in this case, the maximum outer diameter of the covering portion 11 is the same as or smaller than the maximum outer diameter (end portion diameter) of the large diameter portion 3a of the PCF 3, and the end portion of the small diameter portion 3b of the PCF 3 It is in the state which the covering part 11 covered. And PCF3 of such a structure is accommodated in the inside of a sleeve so that it may become the aspect similar to PCF3 shown in FIG.1 and FIG.3-7 in the state covered by the covering part 11. FIG.

It is a vertical side view which shows the optical waveguide structure which concerns on 1st Embodiment of this invention. It is a perspective view which shows the photonic crystal fiber (PCF) which is a component of the optical waveguide structure which concerns on the said 1st Embodiment. It is a vertical side view which shows one modification of the optical waveguide structure which concerns on the said 1st Embodiment. It is a vertical side view which shows the other modification of the optical waveguide structure which concerns on the said 1st Embodiment. It is a vertical side view which shows an example of the optical instrument in which the optical waveguide structure concerning the said 1st Embodiment was used. It is a vertical side view which shows the other example of the optical instrument in which the optical waveguide structure which concerns on the said 1st Embodiment was used. It is a vertical side view which shows the optical waveguide structure which concerns on 2nd Embodiment of this invention. It is a vertical side view which shows an example in which the photonic crystal fiber (PCF) which is a component of the optical waveguide structure which concerns on 1st Embodiment and 2nd Embodiment of this invention was covered by the covering part. It is a vertical side view which shows the other example in which the photonic crystal fiber (PCF) which is a component of the optical waveguide structure which concerns on 1st Embodiment and 2nd Embodiment of this invention was covered by the covering part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical waveguide structure 2 Sleeve 2A Sleeve 2B Sleeve 2C Sleeve 2D Sleeve 3 Photonic crystal fiber (PCF)
3a Large diameter part 3b Small diameter part 4 Support body 4a Inner hole X of support body Center axis

Claims (11)

  An optical waveguide structure characterized in that a photonic crystal fiber having a large-diameter portion on one side of the optical waveguide direction and a small-diameter portion on the other side is fixed to the inner peripheral side of the sleeve whose central axis is along the optical waveguide direction. .   The large diameter portion of the photonic crystal fiber is positioned and fixed with reference to the inner peripheral surface of the sleeve, and an optical fiber or other optical waveguide element is connected to the small diameter portion of the photonic crystal fiber. The optical waveguide structure according to claim 1.   A support body in which an inner hole serving as a positioning reference for an optical fiber or other optical waveguide element is fixed to the inner periphery of the sleeve, and the small diameter portion of the photonic crystal fiber is used with the inner hole of the support body as a reference. The optical waveguide structure according to claim 1 or 2, wherein an optical fiber or other optical waveguide element is connected to the small-diameter portion thereof.   4. The optical waveguide structure according to claim 1, wherein the optical waveguide structure is an optical signal transmitter or a part thereof.   The optical waveguide structure according to any one of claims 1 to 3, wherein a pair of the photonic crystal fibers are provided, and the large-diameter portions of the pair of photonic crystal fibers are spaced apart from each other. body.   6. The optical waveguide structure according to claim 5, wherein the optical waveguide structure is a collimator or a part thereof.   The diameter of the large diameter part of the photonic crystal fiber is 0.5 to 2.5 mm, and the diameter of the small diameter part is 0.05 to 0.25 mm. An optical waveguide structure according to any one of the above.   The optical waveguide structure according to any one of claims 1 to 7, wherein an optical fiber is PC-connected to an end portion of the small-diameter portion of the photonic crystal fiber.   The optical waveguide structure according to claim 1, wherein the photonic crystal fiber is formed by heating and stretching.   The outer peripheral surface of the photonic crystal fiber is covered with a covering portion, and the outer peripheral surface of the covering portion is continuously reduced in diameter from the large diameter portion side toward the small diameter portion side. Item 10. The optical waveguide structure according to any one of Items 1 to 9.   The optical waveguide structure according to any one of claims 1 to 10, wherein an outer peripheral surface of the photonic crystal fiber is covered with a covering portion to form a columnar body.

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