JP5369046B2 - Optical fiber array, optical switch, optical fiber, and end face processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively process an end surface of an optical fiber, where light is inputted and outputted. <P>SOLUTION: An optical fiber array of the present invention includes the optical fibers; and a plate which is the plate for transmitting light to be propagated via the optical fibers and is fixed to the end surfaces of the optical fibers so as to allow one surface to be directed to the end surfaces of the optical fibers and to allow the other surface to be directed outward. An end surface processing method of the present invention includes: a process to prepare the optical fibers; a process to prepare the plate for transmitting the light to be propagated via the optical fibers; and a process to fix the plate to the end surfaces of the optical fibers so as to allow the one surface of the plate to be directed to the end surfaces of the optical fibers and to allow the other surface to be directed outward. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to an optical fiber array, an optical switch, an optical fiber, and an end face processing method.

  Conventionally, in an optical isolator or an optical switch, output light is extracted from an end face of an optical fiber, and light is input again to the end face of the optical fiber. At the end face of an optical fiber where light is input and output, the end face may be inclined for the purpose of reducing the influence of reflected return light, or a filter may be formed on the end face for the purpose of wavelength selection.

  For example, in Patent Document 1, a graded index optical fiber and a coreless optical fiber are provided at the tip of a single mode optical fiber, and the end face of the coreless optical fiber is inclined with respect to the optical axis. This graded index optical fiber has a structure equivalent to a GRIN lens (refractive index distribution type lens) whose refractive index gradually changes from the central axis toward the outer periphery. Here, the light of the single mode optical fiber is converted into parallel light. It functions as a collimator lens that converts to. If the end face of the graded index optical fiber is tilted, the optical characteristics of the lens will change, so a coreless optical fiber is connected to the end of the graded index optical fiber, and the end face of the coreless optical fiber is used as the optical axis. It is inclined with respect to.

JP 2006-47951 A

  Conventionally, in order to reduce the influence of reflected return light on the end face of an optical fiber where light is input and output, it is necessary to polish the end face obliquely. For example, in patent document 1, it was necessary to grind | polish the end surface of the coreless optical fiber located ahead of an optical fiber diagonally.

  However, the process of polishing the end face obliquely requires man-hours for the polishing process, and thus the manufacturing cost is increased. Further, not only when the end face is obliquely polished, but when the end face of the optical fiber where light is input / output is processed, for example, when a filter is formed on the end face of the optical fiber, a manufacturing cost is required. Yes.

  An object of the present invention is to reduce the cost of processing an end face of an optical fiber where light is input and output.

A main invention for achieving the above object includes a plurality of optical fibers, a substrate supporting the plurality of optical fibers, a pressing plate for pressing the plurality of optical fibers supported by the substrate, and the optical fibers. Is fixed to the end faces of the plurality of optical fibers so that one surface faces the end faces of the plurality of optical fibers and the other face faces the outside. A refractive index matching agent serving as an adhesive for adhering and fixing the flat plate between the end surfaces of the plurality of optical fibers and the flat plate, and one surface of the flat plate The other surface of the flat plate is parallel, an inclined surface is formed on the substrate, an inclined surface is formed on the pressing plate, and the inclined surface of the substrate and the inclined surface of the pressing plate are The flat plate is fixed as a fixed surface By one surface and the other surface of the flat plate, so oblique to the optical axis of the plurality of the optical fiber is an optical fiber array, wherein the flat plate is fixed.

  Other characteristics of the present invention will be made clear by the description and drawings described later.

  According to the present invention, it is possible to reduce the cost of processing the end face of an optical fiber.

It is an exploded view of the optical fiber array 1 of 1st Embodiment. It is a flowchart of the manufacturing method of the optical fiber array 1 of 1st Embodiment. 3A and 3B are explanatory diagrams of a procedure for placing the lensed fiber in the V-groove. 4A to 4C are explanatory diagrams for comparison. FIG. 4D is an explanatory diagram of an end face of the optical fiber in the optical fiber array 1 of the first embodiment. FIG. 5A is a front view of the end face of the optical fiber of FIG. 4C for comparison. FIG. 5B is an explanatory diagram showing a state in which a plurality of optical fibers of FIG. 4C are arranged. FIG. 6A is an exploded view of the optical fiber array 1 of the first modification of the first embodiment. FIG. 6B is an explanatory diagram of an end face of the optical fiber in the first modification. FIG. 7A is an exploded view of the optical fiber array 1 of the second modification. FIG. 7B is an explanatory diagram of an end face of the optical fiber in the second modification. It is an exploded view of the optical fiber array 1 of 2nd Embodiment. It is a flowchart of the manufacturing method of the optical fiber array 1 of 2nd Embodiment. 10A and 10B are explanatory diagrams of examples of use of the optical fiber array 1. FIG. 10A is an explanatory diagram of the 1 × 8 optical switch 3. FIG. 10B is an explanatory diagram of the light emitting laser module 5. FIG. 10 is an explanatory diagram of an optical isolator 7.

  At least the following matters will be apparent from the description and drawings described below.

  An optical fiber and a flat plate capable of transmitting light propagating through the optical fiber, wherein one surface faces the end surface of the optical fiber and the other surface faces the outer surface. An optical fiber array characterized by having a flat plate fixed thereto is revealed. According to such an optical fiber array, it is possible to reduce the cost of processing the end face of the optical fiber where light is input and output.

  A plurality of the optical fibers are provided, and the flat plate is fixed to the end faces of the plurality of optical fibers such that one surface faces the end face side of the plurality of optical fibers and the other face faces the outside. It is desirable. Thereby, the direction of the exit surface (or entrance surface) of any optical fiber can be aligned.

  It is desirable that a refractive index matching agent is filled between the end face of the optical fiber and the flat plate. Thereby, Fresnel reflection can be suppressed.

  The refractive index matching agent is preferably an adhesive that adheres and fixes the flat plate. Thereby, the refractive index matching agent can be filled while adhering the flat plates.

  The flat plate is preferably fixed so that the other surface of the flat plate is inclined with respect to the optical axis of the optical fiber. Thereby, the influence of reflected return light can be reduced.

  In addition, the one surface of the flat plate and the other surface of the flat plate are parallel to each other, and the flat plate is fixed to a fixed surface provided obliquely with respect to the optical axis of the optical fiber. It is desirable that the other surface of the optical fiber be inclined with respect to the optical axis of the optical fiber. Further, the other surface of the flat plate is inclined with respect to the one surface of the flat plate, and the flat plate is fixed to a fixed surface provided perpendicular to the optical axis of the optical fiber, It is desirable that the other surface of the flat plate is inclined with respect to the optical axis of the optical fiber. Thereby, the influence of reflected return light can be reduced at low cost.

  It is desirable that the flat plate subjected to the film forming process is fixed to the end face of the optical fiber. Thereby, for example, an antireflection film or a filter can be provided.

  The optical fiber preferably has a GRIN lens. Thereby, parallel light can be input and output.

  Also, an optical switch including such an optical fiber array becomes clear. According to such an optical switch, since the directions of the optical axes of the light emitted from the plurality of optical fibers are uniform, the assembling work is facilitated.

  A flat plate capable of transmitting light propagating through an optical fiber, and fixed to the end face of the optical fiber so that one surface faces the end face of the optical fiber and the other face faces the outside. An optical fiber characterized by having a flat plate becomes clear. According to such an optical fiber, it is possible to reduce the cost of processing the end face of the optical fiber where light is input and output.

  A step of preparing an optical fiber, a step of preparing a flat plate capable of transmitting light propagating through the optical fiber, one surface of the flat plate faces the end surface of the optical fiber, and the other surface of the flat plate is And a step of fixing the flat plate to the end face of the optical fiber so as to face outward. According to such a method, the end face of the optical fiber can be processed at a low cost.

  Preferably, a plurality of optical fibers are prepared, and the flat plate is fixed to the end faces of the plurality of optical fibers so that one surface of the flat plate faces the end face side of the plurality of optical fibers. As a result, the end faces of the plurality of optical fibers can be processed in a lump, so that the cost is low.

  Prior to the step of fixing the flat plate, it is desirable to perform a film forming process on the flat plate in advance. Further, it is desirable to set a plurality of flat plates in the film forming apparatus and perform the film forming process on the plurality of flat plates at once. Thereby, the end surface of the optical fiber can be processed at low cost.

=== First Embodiment ===
<Overall configuration>
FIG. 1 is an exploded view of the optical fiber array 1 of the first embodiment.

  In the following description, when simply described as “optical fiber”, it means that the core is composed of a core that propagates light and a cladding that covers the periphery of the core, but other members that propagate light (for example, GRIN lenses) In the case of being integrally fused and connected, this means including the members. Members connected by a method other than fusion splicing (for example, adhesion using an adhesive) are not integrally spliced and are not included in the “optical fiber”.

  The “end face of the optical fiber” means an end face through which light propagating through the optical fiber is input / output. For example, if a GRIN lens is integrally fused and connected to the end of a single mode optical fiber, the end face of the GRIN lens becomes the “end face of the optical fiber”.

  In the following description, front and rear, top and bottom, and left and right are defined as shown in the figure. That is, the “front-rear direction” is defined along the optical fiber, and the end face side as viewed from the optical fiber is “front”, and the opposite side is “rear”. Further, the direction in which the plurality of optical fibers are arranged is defined as “left-right direction”, and “right” and “left” are defined when viewed from the front side. Further, the front-rear direction and the direction perpendicular to the left-right direction are defined as “up-down direction”, the V-groove side as viewed from the optical fiber is defined as “down”, and the opposite side is defined as “up”.

  The optical fiber array 1 includes a plurality of lensed fibers 10, a V-groove substrate 20, a pressing plate 30, and a flat plate 40. The space surrounded by the V-groove substrate 20, the pressing plate 30 and the flat plate 40 is filled with an adhesive (not shown). The optical fiber array 1 functions as a collimator array.

The lensed fiber 10 is an optical fiber in which a GRIN lens 12 (refractive index distribution type lens) is provided at the tip of a single mode optical fiber 11. The refractive index of the GRIN lens 12 gradually decreases from the central axis toward the outer periphery. Since the graded index optical fiber also has a refractive index that gradually decreases from the central axis toward the outer periphery, the graded index optical fiber is used as the GRIN lens 12. The GRIN lens 12 has a predetermined length so as to function as a collimator lens. Specifically, the GRIN lens 12 has a length that is (2n + 1) / 4 times the pitch length, which is a length necessary for a standing wave of one cycle to stand in the GRIN lens 12 (note that n = 0, 1, 2,... Thereby, the light incident on the GRIN lens 12 from the single mode optical fiber 11 is converted into parallel light in the GRIN lens 12 and output from the GRIN lens 12. Conversely, the parallel light incident on the GRIN lens 12 converges in the GRIN lens 12 and is input from the GRIN lens 12 to the single mode optical fiber 11.
The single mode optical fiber 11 of the lensed fiber 10 and the GRIN lens 12 are fusion-connected. The single mode optical fiber 11 and the GRIN lens 12 have the same diameter (for example, 125 μm), but are slightly thicker than the fiber diameter at the fusion point. However, the diameters of the single mode optical fiber 11 and the GRIN lens 12 do not have to be the same, and the diameter of the GRIN lens 12 may be larger than that of the single mode optical fiber 11.

  The V-groove substrate 20 is a member for arranging the lensed fibers 10. A plurality of V grooves 21 are formed in the V groove substrate 20. Each lensed fiber 10 is supported by the V groove 21 of the V groove substrate 20 and arranged. A portion of the single mode optical fiber 11 in the lensed fiber 10 is supported by the V-groove 21, and a portion of the GRIN lens 12 projects forward from the V-groove 21.

  The front surface of the V-groove substrate 20 is an adhesive surface 22. In the figure, the bonding surface 22 is hatched. Since the flat plate 40 is bonded and fixed to the bonding surface 22, the bonding surface 22 becomes a fixing surface for fixing the flat plate 40. The bonding surface 22 is inclined about 8 degrees with respect to the optical axis of the optical fiber. For this reason, when the flat plate 40 is bonded to the bonding surface 22 of the V-groove substrate 20, the flat plate 40 is attached obliquely with respect to the optical axis of the optical fiber.

  A receiving portion 23 for filling an adhesive is formed on the front side of the V groove 21. The GRIN lens 12 protruding from the V groove 21 is positioned on the receiving portion 23. The length of the receiving portion 23 in the front-rear direction is longer than the length of the GRIN lens 12. For this reason, the tip of the GRIN lens 12 does not protrude ahead of the bonding surface 22 of the V-groove substrate 20. By filling the receiving portion 23 with the adhesive, the adhesive is filled between the end surface of the lensed fiber 10 (the end surface of the GRIN lens 12) and the flat plate 40.

  The pressing plate 30 is a member for pressing the lensed fiber 10 supported by the V-groove substrate 20. When the cross section of the lensed fiber 10 is viewed from the front, the lensed fiber 10 is fixed by a total of three points including two points of the V groove 21 and one point of the holding plate 30. The front surface of the pressing plate 30 is also an adhesive surface 31 (fixed surface). In the figure, the bonding surface 31 is hatched. The adhesive surface 31 of the pressing plate 30 is also inclined with respect to the optical axis of the optical fiber. For this reason, when the flat plate 40 is bonded to the bonding surface 31 of the pressing plate 30, the flat plate 40 is attached obliquely with respect to the optical axis of the optical fiber.

  The flat plate 40 is a light transmissive optical member having an inner plane 41 and an outer plane 42 which are light incident / exit surfaces. The flat plate 40 is made of quartz and can transmit light propagating through the lensed fiber 10. The inner plane 41 of the flat plate 40 faces the end face of the lensed fiber 10 (the end face of the GRIN lens 12), and the outer plane 42 faces the outer side of the optical fiber array 1. Thereby, the light propagated through the lensed fiber 10 is emitted to the outside through the flat plate 40, and conversely, the light incident from the outside enters the lensed fiber 10 through the flat plate 40.

  The shape of the flat plate 40 is a rectangular parallelepiped shape that is long in the left-right direction. For this reason, the cross section of the flat plate 40 seen from the left-right direction is a rectangle, and the inner plane 41 and the outer plane 42 of the flat plate 40 are parallel. However, the shape of the flat plate 40 is not limited to this shape, and may be various shapes such as a round shape, a trapezoidal shape, and a rhombus shape as viewed from the front-rear direction.

  The flat plate 40 is disposed obliquely with respect to the optical axis of the optical fiber. Since the bonding surface 22 of the V-groove substrate 20 and the bonding surface 31 of the pressing plate 30 are formed obliquely, the flat plate 40 is bonded and fixed to these bonding surfaces, so that the flat plate 40 is inclined with respect to the optical axis. Has been placed. Since the inner plane 41 and the outer plane 42 of the flat plate 40 are inclined with respect to the optical axis, the influence of the reflected return light on the end surface of the flat plate 40 can be reduced.

  The V-groove substrate 20, the holding plate 30 and the flat plate 40 are made of quartz made of the same material as the lensed fiber 10. Thereby, the influence of the expansion-contraction by a temperature change can be made small.

  The lensed fiber 10, the V-groove substrate 20, the pressing plate 30, and the flat plate 40 are bonded and fixed with an adhesive. Further, the space surrounded by the V-groove substrate 20, the pressing plate 30 and the flat plate 40 is filled with an adhesive (the adhesive is not shown in FIG. 1). In other words, the receiving portion 23 of the V-groove substrate 20 is filled with the adhesive. As a result, the adhesive is also filled between the end face of the lensed fiber 10 and the inner plane 41 of the flat plate 40.

The refractive index of the adhesive is adjusted to the same degree as the refractive index of the lensed fiber 10 and the flat plate 40 (the refractive index of quartz). In other words, the refractive index of the adhesive is adjusted to be closer to the refractive index of the lensed fiber 10 and the flat plate 40 than the refractive index of air. For this reason, Fresnel reflection can be suppressed by filling an adhesive between the end face of the lensed fiber 10 and the inner plane 41 of the flat plate 40 as compared with the case where no adhesive is filled. That is, the adhesive also serves as a refractive index matching agent.
In order to suppress the loss of light, an adhesive having a good light transmission property is used.

  According to the first embodiment, instead of obliquely polishing the end face of the lensed fiber 10, the influence of the reflected return light is reduced by arranging the flat plate 40 obliquely with respect to the optical axis of the optical fiber. In other words, in the first embodiment, the flat plate 40 is disposed obliquely with respect to the optical axis of the optical fiber, so that oblique polishing of the end face of the optical fiber is unnecessary.

<Manufacturing method>
FIG. 2 is a flowchart of the manufacturing method of the optical fiber array 1 of the first embodiment.

  First, the lensed fiber 10 is prepared (S101). As already described, in the lensed fiber 10, the GRIN lens 12 is fused and connected to the tip of the single mode optical fiber 11. The single mode optical fiber 11 and the GRIN lens 12 have the same diameter (for example, 125 μm), but are slightly thicker than the fiber diameter at the fusion point.

  A coreless optical fiber is not necessary beyond the lensed fiber 10. Further, the end face of the lensed fiber 10 does not have to be obliquely polished.

  Next, the lensed fiber 10 is placed on the V groove 21 of the V groove substrate 20 (S102). As already described, the portion of the single-mode optical fiber 11 in the lensed fiber 10 is supported by the V-groove 21, and the portion of the GRIN lens 12 projects forward from the V-groove 21. However, at this stage, the lensed fiber 10 is placed on the V-groove 21 of the V-groove substrate 20 so that the GRIN lens 12 is positioned in front of the state shown in FIG. Thereby, the fusion point of the single mode optical fiber 11 of the lensed fiber 10 and the GRIN lens 12 is located in front of the front end of the V groove 21 (see FIG. 3A).

  Next, the lensed fiber 10 is gripped by the V-groove substrate 20 and the pressing plate 30 (S103). At this time, first, the holding plate 30 is lightly placed on the lensed fiber 10, and then the single mode optical fiber 11 is slightly pulled rearward to position the lensed fiber 10 in the front-rear direction. Since the fusion point between the single mode optical fiber 11 of the lensed fiber 10 and the GRIN lens 12 is slightly thick, when the single mode optical fiber 11 is pulled rearward, the fusion point becomes the front end of the V groove 21. The front and rear direction of the lensed fiber 10 is positioned (see FIG. 3B). This is why the GRIN lens 12 is positioned in front of the state shown in FIG. 1 in S102. Thereby, the position of the front-back direction of the end surface (end surface of GRIN lens 12) of the some lensed fiber 10 can be arrange | equalized.

  Moreover, the flat plate 40 is prepared in parallel with the process of said S101-S103 (S204). As already described, the flat plate 40 to be prepared is an optical member made of quartz having a rectangular parallelepiped shape that is long in the left-right direction. The cross section of the flat plate 40 viewed from the left-right direction is rectangular, and the inner plane 41 and the outer plane 42 of the flat plate 40 are parallel to each other.

  Next, an adhesive is applied to adhere and fix the lensed fiber 10, the V-groove substrate 20, the pressing plate 30, and the flat plate 40 (S105). Since there is a gap between the V-groove 21 and the lensed fiber 10, an adhesive enters the gap, and the V-groove substrate 20 and the lensed fiber 10 are bonded. Further, with respect to the end surface of the lensed fiber 10, the inner plane 41 of the flat plate 40 faces the end surface of the lensed fiber 10 (the end surface of the GRIN lens 12) and the outer plane 42 faces the outside of the optical fiber array 1. Then, the flat plate 40 is bonded and fixed. At this time, the flat plate 40 is bonded and fixed to the bonding surface 22 of the V-groove substrate 20 and the bonding surface 31 of the pressing plate 30. Since the bonding surface 22 of the V-groove substrate 20 and the bonding surface 31 of the pressing plate 30 are inclined with respect to the optical axis of the optical fiber, the flat plate 40 is bonded and fixed obliquely with respect to the optical axis of the optical fiber. Thereby, the inner plane 41 and the outer plane 42 of the flat plate 40 are inclined with respect to the optical axis of the optical fiber, and the influence of the reflected return light can be reduced.

  Since the adhesive surface 22 of the V-groove substrate 20 and the adhesive surface 31 of the pressing plate 30 are formed obliquely in advance, the flat plate 40 is adhesively fixed to the V-groove substrate 20 at a desired angle (about 8 degrees here). It has become easier. If the bonding surface 31 of the V-groove substrate 20 or the pressing plate 30 is not formed diagonally, it is necessary to bond the flat plate 40 while tilting it with a jig or the like. In this case, the flat plate is caused by curing shrinkage of the adhesive. It is difficult to keep 40 at the desired angle.

  Further, when the flat plate 40 or the like is bonded and fixed, an adhesive is filled in the space surrounded by the V-groove substrate 20, the pressing plate 30, and the flat plate 40 (the receiving portion 23 is filled with the adhesive). As a result, the adhesive is filled between the end face of the lensed fiber 10 and the inner plane 41 of the flat plate 40, and Fresnel reflection can be suppressed.

  As the adhesive, for example, an ultraviolet curable adhesive is used. After the adhesive is applied to the adhesive surface and the adhesive is filled in the space of the receiving portion 23, the adhesive is cured by being irradiated with ultraviolet rays. However, a thermosetting adhesive may be used instead of the ultraviolet curable adhesive.

  When the adhesive is solidified, the optical fiber array 1 shown in FIG. 1 is completed.

  According to the manufacturing method of the first embodiment, it is not necessary to obliquely polish the end face of the optical fiber. Further, since the end faces of a plurality of optical fibers can be collectively processed by simply bonding and fixing one flat plate 40, the number of steps can be reduced and the cost can be reduced.

<Comparison 1>
4A to 4C are explanatory diagrams for comparison.

  In FIG. 4A, a GRIN lens 12 is provided at the tip of the single mode optical fiber 11, and the light of the single mode optical fiber 11 is converted into parallel light by the GRIN lens 12. However, in this configuration, since the end face of the GRIN lens 12 is not inclined with respect to the optical axis, the reflected return light at the end face becomes a problem.

  In FIG. 4B, the end surface of the GRIN lens 12 is inclined with respect to the optical axis. In this configuration, the length of the GRIN lens 12 varies depending on the distance from the central axis of the GRIN lens 12 even if the problem of reflected return light at the end face is reduced. As a result, the optical characteristics of the GRIN lens 12 change, and the GRIN lens 12 cannot function as a collimator lens, so that the light of the single mode optical fiber 11 cannot be converted into parallel light.

  In FIG. 4C, the coreless optical fiber 13 is provided at the tip of the GRIN lens 12, and the end face of the coreless optical fiber 13 is inclined with respect to the optical axis. With this configuration, the influence of the reflected return light at the end face is reduced, and the GRIN lens 12 can function as a collimator lens. However, in this configuration, since it is necessary to connect the coreless optical fiber 13 to the tip of the GRIN lens 12, man-hours for fusion splicing are required. Further, it is necessary to polish the end face of the coreless optical fiber 13 obliquely, which requires man-hours for polishing.

  FIG. 4D is an explanatory diagram of an end face of the optical fiber in the optical fiber array 1 of the first embodiment. A GRIN lens 12 is provided at the tip of the single mode optical fiber 11, and a flat plate 40 disposed obliquely at the tip of the GRIN lens 12 is bonded and fixed. Further, an adhesive functioning as a refractive index matching agent is filled between the GRIN lens 12 and the flat plate 40.

  In the first embodiment, the end surface of the GRIN lens 12 is not obliquely polished, and the GRIN lens 12 can function as a collimator lens. In addition, since it is not necessary to polish the end face of the GRIN lens 12 at an angle, the number of polishing processes can be reduced. In the first embodiment, instead of obliquely polishing the end face, only the flat plate 40 is disposed obliquely and fixed by bonding, so that it can be performed at a lower cost than the fusion process or the oblique polishing process of the coreless optical fiber.

<Comparison 2>
FIG. 5A is a front view of the end face of the optical fiber of FIG. 4C for comparison described above. The arrow in the figure is a symbol for indicating the direction of the end face, and indicates the direction from the rearmost (latest edge) on the obliquely polished end face to the forefront (frontmost edge). Yes.

  FIG. 5B is an explanatory diagram showing a state in which a plurality of the optical fibers shown in FIG. 4C are arranged. As described above, when the optical fibers that are obliquely polished are individually arranged, the directions of the end faces are scattered. Further, if the orientations of the end faces of the respective optical fibers are to be matched with high accuracy, processing will take time and cost.

  FIG. 5C is an explanatory diagram of a light emission surface (or an incident surface) in the optical fiber array 1 of FIG. 4D described above (the optical fiber array 1 of the first embodiment). The circle in the figure indicates the light exit surface (or entrance surface) of the optical fiber on the outer plane 42 of the flat plate 40. That is, the light input to and output from the optical fiber passes through the inside of the circle in the figure. The arrow in the figure indicates the direction from the rearmost part to the frontmost part of the light emission surface (or incident surface) on the outer plane 42. For simplification of explanation, the number of optical fibers is reduced from eight to four.

  As shown in the figure, in the first embodiment, since only one flat plate 40 is disposed obliquely, the light exit surface (or incident surface) of any optical fiber is located on the outer plane 42 of the flat plate 40. The light exit surfaces (or incident surfaces) of the respective optical fibers are aligned. And if optical parts, such as an optical switch, are constituted using optical fiber array 1 of a 1st embodiment, since the direction of the optical axis of the outgoing light (or entrance plane) from each optical fiber is uniform, light Optical axis adjustment with the light input to and output from the fiber array 1 is facilitated, and the assembly work of optical components is facilitated (described later).

  Further, in the first embodiment, since the single flat plate 40 is disposed obliquely and fixed by adhesion, it is easy to align the direction of the light emitting surface (or incident surface) of each optical fiber.

<First Modification>
In the above description, the flat plate 40 has a rectangular cross section, and the inner plane 41 and the outer plane 42 are parallel. However, the shape of the flat plate 40 is not limited to such a shape.

  FIG. 6A is an exploded view of the optical fiber array 1 of the first modification of the first embodiment. FIG. 6B is an explanatory diagram of an end face of the optical fiber in the first modification. In the first modification, the shape of the flat plate 40 is a triangular prism shape.

  The adhesion surface 22 of the V-groove substrate 20 is a surface perpendicular to the optical axis of the optical fiber. Similarly, the adhesive surface 31 of the pressing plate 30 is also a surface perpendicular to the optical axis of the optical fiber. Compared with the configuration of FIG. 1 described above, in the first modification, it is not necessary to form the bonding surface 22 of the V-groove substrate 20 and the bonding surface 31 of the pressing plate 30 obliquely. Can be simplified.

  The flat plate 40 has a triangular prism shape. For this reason, the cross section of the flat plate 40 seen from the left-right direction is a triangle. Also in the first modification, the inner plane 41 of the flat plate 40 faces the end face of the lensed fiber 10 (the end face of the GRIN lens 12), and the outer plane 42 faces the outside of the optical fiber array 1. However, in the first modification, the outer plane 42 of the flat plate 40 is inclined with respect to the inner plane 41.

  Since the bonding surface 22 of the V-groove substrate 20 and the bonding surface 31 of the pressing plate 30 are perpendicular to the optical axis of the optical fiber, when the flat plate 40 is bonded and fixed to the V-groove substrate 20 and the pressing plate 30, the inner plane 41 of the flat plate 40. Are arranged perpendicular to the optical axis of the optical fiber. On the other hand, since the outer plane 42 of the flat plate 40 is inclined with respect to the inner plane 41, the outer plane 42 of the flat plate 40 is disposed obliquely with respect to the optical axis of the optical fiber. For this reason, the influence of the reflected return light at the end face of the flat plate 40 can be reduced.

  The space surrounded by the V-groove substrate 20, the pressing plate 30, and the flat plate 40 is filled with an adhesive (the adhesive is not shown in FIG. 6A). In other words, the receiving portion 23 of the V-groove substrate 20 is filled with the adhesive. As a result, the adhesive is filled between the end face of the lensed fiber 10 and the inner plane 41 of the flat plate 40.

  According to the optical fiber array 1 of the first modified example, instead of obliquely polishing the end face of the lensed fiber 10, the outer plane 42 of the flat plate 40 can be arranged obliquely with respect to the optical axis of the optical fiber. In other words, the optical fiber array 1 of the first modification has a configuration that does not require oblique polishing of the end face of the optical fiber.

  Further, according to this modification, the outer plane 42 of the flat plate 40 is inclined with respect to the optical axis of the optical fiber without forming the bonding surface 22 of the V-groove substrate 20 and the bonding surface 31 of the holding plate 30 obliquely. Can be placed. For this reason, the operation | work which adheres and fixes the flat plate 40 to the V-groove board | substrate 20 or the pressing board 30 becomes easy.

<Second Modification>
FIG. 7A is an exploded view of the optical fiber array 1 of the second modification. FIG. 7B is an explanatory diagram of an end face of the optical fiber in the second modification. Compared to the first modification, the shape of the flat plate 40 is different.

  In the first modification, since the flat plate 40 has a triangular prism shape, the flat plate 40 becomes thin when the angle between the inner plane 41 and the outer plane 42 of the flat plate 40 is small. On the other hand, in the second modified example, since the shape of the flat plate 40 is a trapezoidal column, the flat plate 40 can be set to a desired thickness even if the angle between the inner plane 41 and the outer plane 42 of the flat plate 40 is small. . Thereby, the flat plate 40 can be set to a desired strength.

=== Second Embodiment ===
<Main body configuration>
FIG. 8 is an exploded view of the optical fiber array 1 of the second embodiment. The surface of the flat plate 40 of the second embodiment is coated with an antireflection film 42A.

  The adhesion surface 22 of the V-groove substrate 20 is a surface perpendicular to the optical axis of the optical fiber. Similarly, the adhesive surface 31 of the pressing plate 30 is also a surface perpendicular to the optical axis of the optical fiber. Compared with the configuration of FIG. 1 described above, in the first modification, it is not necessary to form the bonding surface 22 of the V-groove substrate 20 and the bonding surface 31 of the pressing plate 30 obliquely. Can be simplified.

  The flat plate 40 is a light transmissive optical member having an inner plane 41 and an outer plane 42 which are light incident / exit surfaces. The inner plane 41 of the flat plate 40 faces the end face of the lensed fiber 10 (the end face of the GRIN lens 12), and the outer plane 42 faces the outer side of the optical fiber array 1. Thereby, the light propagated through the lensed fiber 10 is emitted to the outside through the flat plate 40, and conversely, the light incident from the outside enters the lensed fiber 10 through the flat plate 40.

  The outer flat surface 42 of the flat plate 40 is coated with an antireflection film 42A. In the drawing, the surface on which the antireflection film 42A is formed is painted black. Light propagating through the optical fiber passes through this black surface. The antireflection film 42A is formed by laminating two kinds of thin films having different refractive indexes. Thereby, the influence of the reflected return light at the end face of the flat plate 40 can be reduced.

  The space surrounded by the V-groove substrate 20, the pressing plate 30, and the flat plate 40 is filled with an adhesive (the adhesive is not shown in FIG. 6A). In other words, the receiving portion 23 of the V-groove substrate 20 is filled with the adhesive. As a result, the adhesive is filled between the end face of the lensed fiber 10 (end face of the GRIN lens 12) and the inner plane 41 of the flat plate 40.

  According to the second embodiment, instead of forming an antireflection film on the end face of the lensed fiber 10, the influence of the reflected return light is reduced by arranging the flat plate 40 having the antireflection film 42A. In other words, in the second embodiment, by arranging the flat plate 40 having the antireflection film 42A, a process for forming the antireflection film on the end face of the optical fiber is unnecessary.

<Manufacturing method>
FIG. 9 is a flowchart of the manufacturing method of the optical fiber array 1 of the second embodiment. S201 to S203 in the figure are the same as S101 to S103 of FIG. 2 of the first embodiment, and thus description thereof is omitted.

  In the second embodiment, the flat plate 40 previously coated with the antireflection film 42A is prepared (S204). The antireflection film 42A is formed by setting a flat plate 40 on a film forming apparatus such as a vapor deposition apparatus and laminating two kinds of thin films having different refractive indexes. Although the volume that can be processed by the film forming apparatus at a time is limited, the target for the film forming process is the flat plate 40 alone, so that a large number of flat plates 40 can be set in the film forming apparatus. That is, since the film forming apparatus can perform the film forming process on a large number of flat plates 40 at a time, the manufacturing cost can be reduced.

  Then, an adhesive is applied to bond and fix the lensed fiber 10, the V-groove substrate 20, the pressing plate 30, and the flat plate 40 (S205). Since there is a gap between the V-groove 21 and the lensed fiber 10, an adhesive enters the gap, and the V-groove substrate 20 and the lensed fiber 10 are bonded. Further, with respect to the end surface of the lensed fiber 10, the inner plane 41 of the flat plate 40 faces the end surface of the lensed fiber 10 (the end surface of the GRIN lens 12) and the outer plane 42 faces the outside of the optical fiber array 1. Then, the flat plate 40 is bonded and fixed. At this time, the flat plate 40 is bonded and fixed to the bonding surface 22 of the V-groove substrate 20 and the bonding surface 31 of the pressing plate 30.

  Further, when the flat plate 40 or the like is bonded and fixed, an adhesive is filled in the space surrounded by the V-groove substrate 20, the pressing plate 30, and the flat plate 40 (the receiving portion 23 is filled with the adhesive). As a result, the adhesive is filled between the end face of the lensed fiber 10 and the inner plane 41 of the flat plate 40, and Fresnel reflection can be suppressed.

  According to the manufacturing method of the second embodiment, the process of forming the antireflection film on the end face of the optical fiber is not necessary, and can be performed at low cost. Further, since the end faces of a plurality of optical fibers can be collectively processed by simply bonding and fixing one flat plate 40, the number of steps can be reduced and the cost can be reduced.

  In the second embodiment, the flat plate 40 is coated with the antireflection film 42A in advance, instead of coating the outer flat surface 42 of the flat plate 40 with the antireflection film 42A after the flat plate 40 is bonded to the V-groove substrate 20 or the like. The flat plate 40 is bonded to the V-groove substrate 20 or the like. Thereby, the antireflection film 42A can be formed at a low cost on the end face of the optical fiber through which light is input and output.

<Comparison 1>
It is conceivable that the antireflection film 42A is formed on the flat plate 40 after the flat plate 40 having no antireflection film 42A is bonded to the V-groove substrate 20 or the like. However, in this case, since it is necessary to set the optical fiber array 1 (the lensed fiber 10, the V-groove substrate 20, the pressing plate 30 and the flat plate 40) in a film forming apparatus having a limited volume, the film forming apparatus is used once. The number that can be processed is reduced.
For this reason, the method of forming the antireflection film 42A on the flat plate 40 after bonding the flat plate 40 to the V-groove substrate 20 or the like increases the manufacturing cost.

<Comparison 2>
It is also conceivable to form an antireflection film directly on the end face of the optical fiber. However, in this case, although the area of the end face of the optical fiber forming the antireflection film is small, it is necessary to set an optical fiber of a certain length in the film forming apparatus, so that the film forming apparatus can process at a time. There are few. Further, when the end portion of the optical fiber is held by, for example, a ferrule and the ferrule is set in the film forming apparatus, the amount that can be processed by the film forming apparatus at one time is further reduced.
For this reason, in the method of directly forming the antireflection film on the end face of the optical fiber, the manufacturing cost is increased.

<Modification>
In the above description, the antireflection film 42 </ b> A is formed on the flat plate 40. However, the thin film formed on the flat plate 40 is not limited to this. For example, the wavelength selection filter may be formed on the flat plate 40, or a thin film that performs other functions may be formed on the flat plate 40. Further, a thick film may be used instead of a thin film.

=== Usage example ===
10A and 10B are explanatory diagrams of examples of use of the optical fiber array 1.

  FIG. 10A is an explanatory diagram of the 1 × 8 optical switch 3. The optical switch 3 has a fixed part 3A and a movable part 3B. The fixed portion 3A has the same configuration as the optical fiber array 1 described above, and eight optical fibers are fixed. The movable portion 3B has substantially the same configuration as the optical fiber array 1 described above, and can move in the direction of the arrow in the drawing while holding one optical fiber and facing the fixed portion 3A.

  If the fixed portion 3A has the same configuration as the optical fiber array 1 described above, the direction of the light emission surface (or incident surface) of each optical fiber of the fixed portion 3A is aligned as described with reference to FIG. 5C above. ing. For this reason, for example, only by adjusting the position of the optical axis of the optical fiber of the movable part 3B and the optical axes of the two uppermost and lowermost optical fibers in the figure of the fixed part 3A, the fixed part The position of the optical axis of another optical fiber of 3A can also be adjusted. Thus, since the direction of the light emission surface (or incident surface) of each optical fiber of the fixed portion 3A is aligned, the assembly of the fixed portion 3A and the movable portion 3B is facilitated.

  Also, if the direction of the light exit surface (or entrance surface) of the optical fiber varies, no matter how much the position is adjusted, the optical axes of all the optical fibers of the fixed portion 3A are the optical axes of the optical fibers of the movable portion 3B. May not be able to meet In this case, the yield at the time of manufacturing the optical switch is deteriorated. On the other hand, if the fixed portion 3A has the same configuration as the optical fiber array 1 described above, the directions of the light emission surfaces (or incident surfaces) of the respective optical fibers of the fixed portion 3A are aligned. The optical axes of all the optical fibers of 3A can be aligned with the optical axes of the optical fibers of the movable portion 3B, and the yield at the time of manufacturing the optical switch 3 is improved.

  FIG. 10B is an explanatory diagram of the light emitting laser module 5. The light emitting laser module 5 includes a light emitting laser array 5A and a light receiving side optical fiber array 5B. The light emitting laser array 5A is composed of a plurality of surface emitting lasers and a plurality of lenses provided corresponding to the respective surface emitting lasers. The light receiving side optical fiber array 5B has the same configuration as the optical fiber array 1 described above, and is provided to face the light emitting laser array 5A.

  As described above, by using the above-described optical fiber array 1 for the light emitting laser module 5, as in the case of the optical switch 3, the assembly of optical components is facilitated. Further, by using the above-described optical fiber array 1 for the light emitting laser module 5, as in the case of the optical switch 3, the yield at the time of manufacturing the light emitting laser module 5 is improved.

As described above, by using the optical fiber array 1 described above, it becomes easy to assemble optical components such as the optical switch 3 and the light emitting laser module 5, and the optical components can be manufactured at low cost.
Moreover, since the end face direction of the optical fiber array 1 is not different as shown in FIG. 5B of the comparative example, the yield in manufacturing optical components such as the optical switch 3 and the light emitting laser module 5 can be improved. You can also.

=== Other Embodiments ===
The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be modified and improved as follows, for example, without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

<About optical fiber arrangement>
In the above-described embodiment, a plurality of optical fibers are arranged in one row (one-dimensional) in the left-right direction. However, the present invention is not limited to this. For example, the optical fibers may be arranged two-dimensionally, such as arranging two rows of optical fibers in two rows. When optical fibers are arranged two-dimensionally, for example, a plurality of optical fibers may be arranged in a circle.

<About the number of optical fibers>
In the above-described embodiment, the flat plate 40 is bonded and fixed to a plurality of optical fibers. However, the present invention is not limited to this. For example, a flat plate may be bonded and fixed to one optical fiber.

  FIG. 11 is an explanatory diagram of an optical isolator 7 employing such a configuration. The optical isolator 7 includes an incident portion 7A that holds the incident side optical fiber, an emission portion 7B that holds the emission side optical fiber, and an optical isolator element 7C. The incident portion 7A and the emitting portion 7B are configured such that a flat plate is bonded and fixed to one optical fiber. The optical isolator element 7C is an optical element that transmits light from the incident side optical fiber toward the output side optical fiber, but does not transmit light from the output side optical fiber to the incident side optical fiber.

  In such an optical isolator 7 as well, as in the case of the optical switch 3, assembly is facilitated by adopting a configuration in which a flat plate is bonded and fixed to one optical fiber.

<About optical fiber>
In the above-described embodiment, the optical fiber (lensed fiber 10) in which the GRIN lens 12 is provided at the tip of the single mode optical fiber 11 is used. However, the configuration of the optical fiber is not limited to this.

  For example, the GRIN lens may not be provided at the end of the single mode optical fiber (that is, the optical fiber array may not be a collimator array). In the case of such an optical fiber, if there is dust or the like in the optical path or the optical axis is shifted, the connection loss increases. However, even with such a configuration, a flat plate can be disposed obliquely at the tip of the optical fiber, or a flat plate having an antireflection film can be disposed at the tip of the optical fiber. If the flat plate is simply bonded and fixed to the tip of the optical fiber, processing of the end face of the optical fiber where light is input and output can be performed at low cost.

  Also, instead of the single-mode optical fiber (SMF), the multi-mode optical fiber (MMF), dispersion-shifted optical fiber (DSF), dispersion-compensating optical fiber (DCF), polarization-maintaining optical fiber, etc. A flat plate may be bonded and fixed. Further, not only when these optical fibers or single mode optical fibers (SMF) are used alone, but also when two or more optical fibers are used in combination by fusion splicing, etc. A flat plate may be bonded and fixed to the tip of the fiber. Also in this case, the processing of the end face of the optical fiber where light is input and output can be performed at low cost.

<About the adhesive>
The adhesive of the above-described embodiment also serves as a refractive index matching agent, and the adhesive is filled between the end face of the optical fiber and the flat plate. However, a refractive index matching agent different from the adhesive may be filled between the end face of the optical fiber and the flat plate. In this case, although it is necessary to prepare both an adhesive and a refractive index matching agent, Fresnel reflection can be suppressed.

<About adhesive surface>
In the above-described embodiment, both the V-groove substrate 20 and the pressing plate 30 are provided with adhesive surfaces. However, either one of the bonding surfaces may be provided. Moreover, as long as a flat plate can be bonded and fixed to the end face of the optical fiber, an adhesive surface may be provided on a member different from the V-groove substrate 20 and the pressing plate 30.

<About fixing method>
In the above-described embodiment, the flat plate is bonded and fixed to the end face of the optical fiber using an adhesive. However, the fixing method is not limited to adhesion, and other methods may be used. However, fixing by bonding can be performed at low cost because the flat plate can be fixed to the end face of the optical fiber by a simple process.

  Further, it is not necessary to fix the flat plate directly to the end face of the optical fiber, and it may be fixed indirectly. For example, the end face of the optical fiber and the flat plate may be indirectly fixed by fixing the flat plate to the V-groove substrate while fixing the side surface of the optical fiber to the V-groove substrate. In this case, a refractive index matching agent is preferably filled between the end face of the optical fiber and the flat plate.

1 optical fiber array,
3 Optical switch, 3A fixed part, 3B movable part,
5 Light emitting laser module, 5A Light emitting laser array, 5B Light receiving side optical fiber array,
7 optical isolator, 7A incident part, 7B emission part, 7C optical isolator element,
10 lensed fiber, 11 single mode optical fiber, 12 GRIN lens,
13 coreless optical fiber,
20 V-groove substrate, 21 V-groove, 22 bonding surface (fixed surface), 23 receiving portion,
30 pressure plate, 31 adhesive surface (fixed surface),
40 flat plate, 41 inner plane, 42 outer plane, 42A antireflection film

Claims (7)

A plurality of optical fibers;
A substrate for supporting a plurality of the optical fibers;
A pressing plate for pressing the plurality of optical fibers supported by the substrate;
A flat plate capable of transmitting light propagating through the optical fiber, wherein one surface faces the end surface side of the plurality of optical fibers, and the other surface faces the outside. A flat plate fixed to the
Between the end faces of the plurality of optical fibers and the flat plate, a refractive index matching agent serving as an adhesive for bonding and fixing the flat plate is filled,
One surface of the flat plate and the other surface of the flat plate are parallel,
An inclined surface is formed on the substrate, an inclined surface is formed on the pressing plate, and the flat plate is fixed using the inclined surface of the substrate and the inclined surface of the pressing plate as a fixed surface, The optical fiber array, wherein the flat plate is fixed so that one surface and the other surface of the flat plate are inclined with respect to an optical axis of the plurality of optical fibers. The optical fiber array according to claim 1 , wherein
The optical fiber array, wherein the flat plate subjected to the film forming process is fixed to an end face of the optical fiber. The optical fiber array according to claim 1 or 2 ,
The optical fiber includes a GRIN lens. The optical switch provided with the optical fiber array in any one of Claims 1-3 . Preparing a plurality of optical fibers;
Preparing a substrate for supporting a plurality of the optical fibers;
Preparing a pressing plate for pressing the plurality of optical fibers supported by the substrate;
A step of preparing a flat plate in which one surface and the other surface are parallel and capable of transmitting light propagating through the optical fiber;
Fixing the flat plate to the end surfaces of the plurality of optical fibers such that one surface of the flat plate faces the end surface side of the plurality of optical fibers and the other surface of the flat plate faces outward. Have
Between the end faces of the plurality of optical fibers and the flat plate, a refractive index matching agent serving as an adhesive for fixing the flat plate is filled,
An inclined surface is formed on the substrate, an inclined surface is formed on the pressing plate, and the flat plate is fixed using the inclined surface of the substrate and the inclined surface of the pressing plate as a fixed surface, An end face machining method, comprising fixing the flat plate so that one surface and the other surface of the flat plate are inclined with respect to an optical axis of the plurality of optical fibers. The end face processing method according to claim 5 ,
An end face processing method, wherein a film forming process is performed on the flat plate in advance before the step of fixing the flat plate. The end face processing method according to claim 6 ,
An end face processing method, wherein a plurality of flat plates are set in a film forming apparatus, and a film forming process is performed on the plurality of flat plates at once.

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