JP2012008006A - Optical fiber measurement module, optical fiber measurement device, and optical fiber measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber measurement module, an optical fiber measurement device, and an optical fiber measurement method for simply measuring an optical characteristic of an optical fiber having a core at a position apart from the center axis like a multicore optical fiber.SOLUTION: An optical fiber measurement device 1A comprises: a single mode optical fiber 31; a measurement optical fiber 32 with an end face where one of peripheral cores is optically connected with the single mode optical fiber 31; support means 33 for supporting the measurement optical fiber 32 and an measurement object optical fiber 100 so that the other end face of the measurement optical fiber 32 and one end face of the measurement object optical fiber 100 coaxially face each other; rotation means 34 for rotating the measurement optical fiber 32 and the measurement object optical fiber 100 relative to each other; a light source 2 for making light incident to the other end face of the single mode optical fiber 31; and light detection means 6 for detecting intensity of light emitted by the peripheral core.

Description

  The present invention relates to an optical fiber measurement module, an optical fiber measurement device, and an optical fiber measurement method.

  In Patent Document 1, the optical axis of an optical component is adjusted so that the optical component is finely moved so as to pass light from one side to the other side of the optical components that perform optical coupling and the maximum optical coupling is obtained to align the optical axis center. A method is described. In the method described in this document, one or both of optical components that perform optical coupling are finely moved in two directions orthogonal to each other on a plane perpendicular to the optical axis to measure the optical coupling strength at a plurality of positions. The peak position of the optical coupling strength is obtained based on the measurement data, and the optical axis position of the optical component is aligned with this peak position.

  Patent Document 2 describes a method of aligning the optical axis of a semiconductor element such as an avalanche photodiode and an optical transmission line, and an apparatus therefor. The method described in this document obtains the relationship of the optical coupling ratio with respect to the relative position of the semiconductor element and the optical transmission path and determines the position corresponding to the center of gravity of the optical coupling ratio distribution with respect to the relative position of the semiconductor element and the optical transmission path. The optical axis is aligned as the optimum position.

  In addition, the method of measuring the loss of an optical fiber is defined in Japanese Industrial Standard (JIS S 6823). In this method, light is made incident from one end of the optical fiber, and the optical fiber loss is measured by measuring the light intensity at the other end using a power meter. At that time, a dummy fiber for optically coupling one end of the optical fiber and the light source and a dummy fiber for optically coupling the other end of the optical fiber and the power meter are required. In general, since only one optical fiber core is provided at the center of the clad, it is easy to adjust the optical axis when connecting these dummy fibers and the optical fiber to be measured.

JP-A-6-281850 JP 63-041814 A

  In recent years, in an optical communication system such as FTTH (FiberTo The Home), a wide optical fiber storage space is required in a storage station as the number of communication terminals increases. As a countermeasure, a multicore optical fiber having a plurality of cores in one fiber has been actively studied. The multi-core optical fiber has a core disposed at a position away from the center in addition to the core disposed on the central axis of the fiber in a cross section perpendicular to the longitudinal direction. Alternatively, a plurality of cores arranged at a predetermined distance from the central axis of the fiber are arranged at equal intervals in the circumferential direction. However, the existing optical fiber measuring apparatus does not support the multi-core optical fiber having such a configuration. Unlike when measuring a single-core optical fiber in which a single core is placed only in the center, when measuring a multi-core optical fiber, the measurement light is applied to the core at a predetermined distance from the center axis of the fiber. This is because it is difficult to adjust the optical axis of the incident light.

  The present invention has been made in view of such problems, and an optical fiber measurement module that can easily measure the optical characteristics of an optical fiber having a core at a position away from the central axis, such as a multi-core optical fiber, An object of the present invention is to provide an optical fiber measuring apparatus and an optical fiber measuring method.

  In order to solve the above-described problem, an optical fiber measurement module according to the present invention includes a first core and a first cladding that covers the first core, and the central axis of the first core is the first axis. An optical fiber measurement module used for measuring optical characteristics of an optical fiber to be measured that is separated from a central axis of one cladding by a predetermined distance, the second core, and a second core that covers the second core A single-mode optical fiber having a cladding, the second core being disposed on the central axis of the second cladding, a third core, and a third cladding covering the third core; A measurement optical fiber in which the central axis of the third core is separated from the central axis of the third cladding by a predetermined distance, and the third core is optically coupled to one end of the second core at one end surface; The other end of the measurement optical fiber and the optical fiber to be measured Comprising a support means for supporting the measuring optical fiber and optical fiber to be measured so that the one end face are opposed coaxially, and a measurement optical fiber and rotating means for relatively rotating the optical fiber to be measured.

  In the optical fiber measurement module, the support means may have a groove having a V-shaped cross section for accommodating the measurement optical fiber and the optical fiber to be measured. Alternatively, in the optical fiber measurement module, the support means has a substantially cylindrical sleeve into which a substantially cylindrical holding member attached to each end of the measurement optical fiber and the optical fiber to be measured can be inserted from both ends. May be.

  In the optical fiber measurement module, the optical fiber to be measured and the optical fiber for measurement each have a plurality of first and third cores, and the first cores and the second cores have a predetermined interval. It may be arranged open.

  The optical fiber measuring apparatus according to the present invention has a first core and a first cladding covering the first core, and the central axis of the first core is predetermined from the central axis of the first cladding. An optical fiber measuring apparatus for measuring optical characteristics of optical fibers to be measured that are separated from each other, the optical fiber measuring apparatus having a second core and a second cladding that covers the second core, and the second core is a second core A first single-mode optical fiber disposed on the central axis of the cladding, a third core, and a third cladding covering the third core, the central axis of the third core being the first A first measurement optical fiber that is separated from the central axis of the third clad by a predetermined distance and that has a third core optically coupled to one end of the second core at one end surface; The other end of the fiber and the one end of the optical fiber to be measured are concentrically opposed. First supporting means for supporting the first measuring optical fiber and the measured optical fiber, a first rotating means for relatively rotating the first measuring optical fiber and the measured optical fiber, A light source that makes light incident on the other end of the second core of the single-mode optical fiber, and a light detection unit that detects the intensity of the light emitted from the first core on the other end surface of the optical fiber to be measured. Prepare.

  In the optical fiber measuring apparatus, the first support means may have a groove having a V-shaped cross section for accommodating the first measuring optical fiber and the measured optical fiber. Alternatively, the first support means has a substantially cylindrical sleeve into which a substantially cylindrical holding member attached to each end of the first measurement optical fiber and the measured optical fiber can be inserted from both ends. May be.

  In the optical fiber measuring apparatus, the optical fiber to be measured and the first optical fiber for measurement each have a plurality of first and third cores, and the first cores and the second cores are predetermined. You may arrange | position at intervals.

  In addition, the optical fiber measurement device includes a light detection unit in which the light detection unit is optically coupled to the other end surface of the optical fiber to be measured and collectively detects the intensity of light emitted from the plurality of first cores. May be. In this case, the light detection unit includes a large-diameter optical fiber having a core having a thickness that includes all of the plurality of first cores of the optical fiber to be measured, and the intensity of light emitted from the plurality of first cores. May be detected through a large-diameter optical fiber. Alternatively, the light detection unit may include a photodiode that is optically coupled to the other end surface of the optical fiber to be measured, and the light intensity emitted from the plurality of first cores may be detected by the photodiode.

  Further, in the optical fiber measuring apparatus, the light detection means has a fourth core and a fourth clad covering the fourth core, and the fourth core is disposed on the central axis of the fourth clad. A second single-mode optical fiber, a fifth core, and a fifth clad covering the fifth core, the central axis of the fifth core being a predetermined distance from the central axis of the fifth cladding A second measuring optical fiber that is separated and optically coupled to one end of the fourth core at one end face, the other end face of the second measuring optical fiber, and the optical fiber to be measured The second measurement optical fiber and the second support means for supporting the optical fiber to be measured so that the other end surface of the optical fiber is coaxially opposed to each other, and the second optical fiber for measurement and the optical fiber to be measured are relatively Second rotating means for rotating, and emitted from the plurality of first cores. That the intensity of the light may be detected through the second measurement optical fiber and the second single-mode optical fiber.

  The optical fiber measurement method according to the present invention includes a first core and a first cladding that covers the first core, and the central axis of the first core is predetermined from the central axis of the first cladding. A method for measuring optical characteristics of optical fibers to be measured that are separated from each other, comprising: a second core; and a second clad covering the second core, wherein the second core is formed of the second clad. One end of the second core of the first single-mode optical fiber disposed on the central axis, the third core, and a third cladding covering the third core, A first step of optically coupling, at one end face of the first measurement optical fiber, a third core of the first measurement optical fiber whose central axis is separated from the central axis of the third cladding by a predetermined distance. And the other end face of the first measuring optical fiber and one end face of the optical fiber to be measured A second step of supporting the first measurement optical fiber and the optical fiber to be measured so that the two are coaxially opposed to each other, and a third step of injecting light into the other end of the second core of the first single mode optical fiber. And a fourth step of detecting the intensity of light emitted from the first core at the other end face of the optical fiber to be measured while rotating the first optical fiber for measurement around the central axis of the third cladding. Including.

  In the optical fiber measurement method, the first measurement optical fiber and the optical fiber to be measured may be placed in a groove having a V-shaped cross section in the second step. Alternatively, in the optical fiber measurement method, in the second step, a substantially cylindrical holding member attached to each end of the measurement optical fiber and the optical fiber to be measured is inserted into both ends of the substantially cylindrical sleeve. May be.

  Further, in the optical fiber measurement method, the optical fiber under measurement and the first optical fiber for measurement each have a plurality of first and third cores, and the first cores and the second cores are predetermined. You may arrange | position at intervals.

  The optical fiber measurement method may collectively detect the intensity of light emitted from the plurality of first cores on the other end surface of the optical fiber to be measured in the fourth step. In this case, in the fourth step, the large-diameter optical fiber having a core having a thickness that includes all of the plurality of first cores of the optical fiber to be measured with respect to the intensity of light emitted from the plurality of first cores. You may detect via. Alternatively, in the fourth step, the intensity of light emitted from the plurality of first cores may be detected by a photodiode optically coupled to the other end face of the optical fiber to be measured.

  Further, the optical fiber measurement method has a fourth core and a fourth clad covering the fourth core in the first step, and the fourth core is on the central axis of the fourth clad. One end of the fourth core of the second single-mode optical fiber disposed, a fifth core, and a fifth cladding covering the fifth core, the central axis of the fifth core being the first axis 5 is optically coupled to the fifth core of the second measuring optical fiber, which is separated from the central axis of the clad 5 by a predetermined distance, at one end face of the second measuring optical fiber, and during the second step. , Supporting the second measurement optical fiber and the optical fiber to be measured so that the other end surface of the second optical fiber for measurement and the other end surface of the optical fiber to be measured are coaxially opposed, and during the fourth step, Rotating the second measuring optical fiber around the central axis of the fifth cladding , The intensity of the light emitted from the other end of the fourth core of the second single-mode optical fiber may be detected.

  According to the optical fiber measurement module, the optical fiber measurement device, and the optical fiber measurement method according to the present invention, it is possible to easily measure the optical characteristics of an optical fiber having a core at a position away from the central axis, such as a multi-core optical fiber.

FIG. 1 is a diagram schematically showing an overall configuration of an optical fiber measuring apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a structure example of an optical fiber to be measured which is measured by an optical fiber measuring device. FIG. 3 is a diagram illustrating an example of a cross-sectional structure of a single mode optical fiber. FIG. 4 is a diagram illustrating an example of a cross-sectional structure of the measurement optical fiber. FIG. 5 is a diagram illustrating a state in which the single mode optical fiber and the measurement optical fiber are bonded to each other. FIG. 6 is an enlarged perspective view showing a joint portion between the single mode optical fiber and the measurement optical fiber. FIG. 7 is a diagram showing an example of the support means. FIG. 8 is a diagram showing an example of the support means. FIG. 9 is a flowchart showing the optical fiber measurement method according to the first embodiment. FIG. 10 is a diagram schematically illustrating a second step of the optical fiber measurement method. FIG. 11 is a diagram schematically illustrating a fourth step of the optical fiber measurement method. FIG. 12 is a diagram schematically showing an overall configuration of an optical fiber measurement device according to the second embodiment of the present invention. FIG. 13 is a side cross-sectional view showing a large-diameter optical fiber and a measured optical fiber that are arranged to face each other. FIG. 14 is a diagram schematically showing an overall configuration of an optical fiber measurement device according to the third embodiment of the present invention. FIG. 15 is a side sectional view showing a configuration in the vicinity of the light detection means. FIG. 16 is a diagram illustrating a structure example of an optical fiber to be measured.

  Embodiments of an optical fiber measurement module, an optical fiber measurement device, and an optical fiber measurement method according to the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a diagram schematically showing an overall configuration of an optical fiber measuring apparatus 1A according to the first embodiment of the present invention. FIG. 2 is a diagram showing an example of the structure of the optical fiber 100 to be measured measured by the optical fiber measuring device 1A. The optical fiber measurement device 1A of the present embodiment is an optical characteristic (core loss or the like) of an optical fiber 100 to be measured having a core disposed at a predetermined distance from a central axis of a clad, such as a multi-core optical fiber. It is a device for measuring.

  An optical fiber 100A to be measured shown in FIG. 2A includes a central core 101 disposed on the fiber center axis C1 and four peripheral cores (first cores) 102 disposed around the central core 101. And a clad (first clad) 103 covering these cores 101, 102. The four peripheral cores 102 are arranged away from the fiber center axis C1 by a predetermined distance L1, and the peripheral cores 102 are equally arranged with a predetermined interval L2.

  2B includes a central core 101 disposed on the fiber center axis C1 and six peripheral cores (first core) disposed around the central core 101. ) 104 and a clad (first clad) 105 covering these cores 101 and 104. The six peripheral cores 104 are arranged away from the fiber center axis C1 by a predetermined distance L3, and the peripheral cores 104 are equally arranged with a predetermined interval L4.

  As shown in FIG. 1, the optical fiber measurement device 1 </ b> A includes a light source 2 and a first optical fiber measurement module 3. The light source 2 and the optical fiber measurement module 3 are means for making measurement light incident on the peripheral core 102 (or 104) of the optical fiber 100 to be measured at one end face of the optical fiber 100 to be measured. Furthermore, the optical fiber measurement device 1A includes a light detection means 6. The light detection means 6 is means for detecting the intensity of the measurement light emitted from the peripheral core 102 (or 104) of the measured optical fiber 100 at the other end face of the measured optical fiber 100. The light detection means 6 of this embodiment includes a second optical fiber measurement module 4 and a power meter 5.

  The optical fiber measurement module 3 includes a first single mode optical fiber 31, a first measurement optical fiber 32, a first support means 33, and a first rotation means 34. The optical fiber measurement module 4 includes a second single mode optical fiber 41, a second measurement optical fiber 42, second support means 43, and second rotation means 44.

  FIG. 3 is a diagram illustrating an example of a cross-sectional structure of the single mode optical fibers 31 and 41. As shown in the figure, the single mode optical fiber 31 has a single core 31a (second core) and a clad 31b (second clad) covering the single core 31a. The single core 31a is disposed on the central axis C2 of the clad 31b (that is, the central axis of the single mode optical fiber 31). Similarly, the single mode optical fiber 41 has a single-core core 41a (fourth core) and a clad 41b (fourth clad) that covers the single-core core 41a. The single core 41a is disposed on the central axis C2 of the clad 41b (that is, the central axis of the single mode optical fiber 41).

  FIG. 4 is a diagram illustrating an example of a cross-sectional structure of the measurement optical fibers 32 and 42. In the present embodiment, the measurement optical fibers 32 and 42 have the same cross-sectional structure as the measurement optical fiber 100, and the diameters of the measurement optical fibers 32 and 42 are equal to the diameter of the measurement optical fiber 100.

  For example, the measurement optical fiber 32A shown in FIG. 4A includes a central core 32a, four peripheral cores (third cores) 32b arranged around the central core 32a, and the cores 32a, And a clad (third clad) 32c covering 32b. The central core 32a is disposed on the central axis C3 of the clad 32c (that is, the central axis of the measurement optical fiber 32A). The four peripheral cores 32b are spaced apart from the central axis C3 by a predetermined distance L1, and the peripheral cores 32b are equally disposed with a predetermined distance L2.

  Similarly, the measurement optical fiber 42A includes a central core 42a, four peripheral cores (fifth core) 42b arranged around the central core 42a, and a clad (fifth core) covering these cores 42a and 42b. Clad) 42c. The center core 42a is disposed on the center axis C3 of the clad 42c (that is, the center axis of the measurement optical fiber 42A). The four peripheral cores 42b are spaced apart from the central axis C3 by a predetermined distance L1, and the peripheral cores 42b are equally disposed with a predetermined distance L2.

  Also, the measurement optical fiber 32B shown in FIG. 4B includes a central core 32a, six peripheral cores (third cores) 32d arranged around the central core 32a, and the cores 32a, And a clad (third clad) 32e covering 32d. The central core 32a is disposed on the central axis C3 of the clad 32e (that is, the central axis of the measurement optical fiber 32A). The six peripheral cores 32d are arranged away from the central axis C3 by a predetermined distance L3, and the peripheral cores 32d are equally arranged with a predetermined interval L4.

  Similarly, the measurement optical fiber 42B includes a central core 42a, six peripheral cores (fifth core) 42d disposed around the central core 42a, and a clad (fifth core) covering these cores 42a and 42d. Clad) 42e. The central core 42a is disposed on the central axis C3 of the clad 42e (that is, the central axis of the measurement optical fiber 42A). The six peripheral cores 42d are arranged apart from the central axis C3 by a predetermined distance L4, and the peripheral cores 42d are equally arranged with a predetermined interval L4.

  In the optical fiber measurement module 3, the single mode optical fiber 31 and the measurement optical fiber 32 are bonded to each other. In the optical fiber measurement module 4, the single mode optical fiber 41 and the measurement optical fiber 42 are joined to each other. FIG. 5 is a diagram showing a state in which the single mode optical fiber 31 (41) and the measurement optical fiber 32 (42) are bonded to each other. As shown in FIG. 5, the end of the single mode optical fiber 31 (41) is held by a holding member 35 (45) such as a single-core FA (Fiber Array) substrate, a zirconia ferrule, or a glass capillary. Similarly, the end of the measurement optical fiber 32 (42) is held by a holding member 36 (46). The holding member 35 (45) and the holding member 36 (46) are joined to each other via the adhesive layer 37 (47).

  FIG. 6 is an enlarged perspective view showing a joint portion between the single mode optical fiber 31 (41) and the measurement optical fiber 32 (42). As shown in FIG. 6, the single mode optical fiber 31 (41) is joined eccentrically with respect to the central axis of the measurement optical fiber 32 (42). Then, on one end face of the measurement optical fiber 32 (42), the peripheral core 32b (42b) of the measurement optical fiber 32 (42) is one end of the single core 31a (41a) of the single mode optical fiber 31 (41). Are aligned and optically coupled. 6 illustrates the structure of the measurement optical fiber 32 (42) illustrated in FIG. 4A, the structure of the measurement optical fiber 32 (42) is illustrated in FIG. It may be the structure shown or other structures.

  The support means 33 supports the measurement optical fiber 32 and the measured optical fiber 100 so that the other end face of the measurement optical fiber 32 and the one end face of the measured optical fiber 100 are concentrically opposed. Further, the support means 43 supports the measurement optical fiber 42 and the measured optical fiber 100 so that the other end surface of the measurement optical fiber 42 and the other end surface of the measured optical fiber 100 face each other coaxially.

  7 and 8 are diagrams showing examples of the support means 33 and 43. FIG. For example, the support means 33A (43A) shown in FIG. 7 has a substantially flat shape. A groove 33a (43a) having a V-shaped cross section for accommodating the measurement optical fiber 32 (42) and the measured optical fiber 100 is formed on one plate surface. The groove 33a preferably has a size (depth) on which an optical fiber having a diameter of 125 μm can be mounted. The optical fiber for measurement 32 (42) and the optical fiber to be measured 100 are positioned in a plane perpendicular to the central axis by abutting against the side wall of the groove 33a (43a), and their end faces are opposed to each other with the same axis. To do. However, the measurement optical fiber 32 (42) and the measured optical fiber 100 are not fixed to the support means 33A (43A), and can be rotated around their respective central axes.

  Further, for example, the support means 33B (43B) shown in FIG. 8 includes a split sleeve 39 having a substantially cylindrical shape. The inner diameter of the split sleeve 39 is the diameter of the cylindrical holding member 38 (48) provided at the end of the measuring optical fiber 32 (42) and the cylindrical holding provided at the end of the measured optical fiber 100. It is slightly larger than the diameter of the member 110. The diameter of the holding member 38 (48) and the diameter of the holding member 110 are, for example, 2.5 mm.

  As shown in FIG. 8A, the holding member 38 (48) of the measurement optical fiber 32 (42) is inserted into one end of the split sleeve 39, and the holding member 110 of the optical fiber 100 to be measured is inserted into the other end. Is inserted. The holding members 38 (48) and 100 are constituted by, for example, a single-core FA substrate, a zirconia ferrule, or a glass capillary. Then, as shown in FIG. 8B, these holding members 38 (48) and the holding member 110 come into contact with each other inside the split sleeve 39, so that the end faces thereof are coaxially opposed to each other. However, the measurement optical fiber 32 (42) and the optical fiber to be measured 100 are not fixed to the split sleeve 39, and can be rotated around their respective central axes.

  Each of the rotating means 34 and 44 relatively rotates the measurement optical fibers 32 and 42 and the optical fiber 100 to be measured. In the present embodiment, the rotating means 34 and 44 rotate the measurement optical fibers 32 and 42 around the central axis, respectively. Each of the rotation means 34 and 44 has a configuration capable of precisely controlling the rotation angle of each of the measurement optical fibers 32 and 42. Such a configuration is realized, for example, by gripping the side surface of the measurement optical fiber 32 (42) and rotating the measurement optical fiber 32 (42) by an arbitrary angle by a stepping motor. As such rotation means 34 and 44, for example, an optical fiber rotation stage (such as F266 manufactured by Suruga Seiki) is suitable.

  The light source 2 is optically coupled to the other end of the core 31a of the single mode optical fiber 31, and makes light incident on the other end of the core 31a. The light incident from the light source 2 is light for measuring optical characteristics (such as loss) of the optical fiber 100 to be measured, and is, for example, infrared laser light used in an optical communication system.

  The power meter 5 is optically coupled to the other end of the core 41a of the single mode optical fiber 41, and detects the intensity of light emitted from the other end of the core 41a. The power meter 5 includes a light detection element such as a photodiode.

  Hereinafter, the operation of the optical fiber measurement device 1A will be described together with the optical fiber measurement method according to the present embodiment. FIG. 9 is a flowchart showing the optical fiber measurement method according to the present embodiment. 10 and 11 are diagrams schematically showing the second step and the fourth step of the optical fiber measuring method.

  First, single-mode optical fibers 31 and 41 and measurement optical fibers 32 and 42 having the same structure as the measured optical fiber 100 are prepared. These optical fibers 31, 32, 41 and 42 are mounted on a fiber array or a glass capillary, and each end face is polished. Thereafter, for example, as shown in FIG. 6, one end of the single core 31 a of the single mode optical fiber 31 and the peripheral core 32 b (or 32 d) of the measurement optical fiber 32 are connected to one end of the measurement optical fiber 32. After aligning and optically connecting, the adhesive is fixed. Similarly, one end of the single-core core 41a of the single-mode optical fiber 41 and the peripheral core 42b (or 42d) of the measurement optical fiber 42 are aligned at one end surface of the measurement optical fiber 42, and optically After bonding, the adhesive is fixed (first step S1).

  Next, as shown in FIG. 10, the measurement optical fiber 32 and the measured optical fiber 100 are supported so that the other end face of the measurement optical fiber 32 and the one end face of the measured optical fiber 100 face each other coaxially. . Similarly, the measurement optical fiber 42 and the measured optical fiber 100 are supported so that the other end face of the measurement optical fiber 42 and the other end face of the measured optical fiber 100 are coaxially opposed (second step S2). As the supporting means used at this time, for example, the one shown in FIG. 7 or FIG. 8 is preferable. Further, quartz matching oil is provided between the other end face of the measurement optical fiber 32 and one end face of the optical fiber 100 to be measured and between the other end face of the measurement optical fiber 42 and the other end face of the optical fiber 100 to be measured. It is good to apply.

  Subsequently, measurement light is incident from the light source 2 to the other end of the single core 31a of the single mode optical fiber 31 (third step S3). This light passes through the single core 31 a of the single mode optical fiber 31 and the peripheral core 32 b (or 32 d) of the measurement optical fiber 32, and enters the peripheral core 102 (or 104) at one end face of the optical fiber 100 to be measured. . This light passes through the peripheral core 102 (or 104), and then is emitted from the peripheral core 102 (or 104) at the other end face of the optical fiber 100 to be measured, and the peripheral core 42b (or 42d) of the measurement optical fiber 42 and The power reaches the power meter 5 through the single core 41 a of the single mode optical fiber 41.

  Subsequently, as shown in FIG. 11, the intensity of light is detected by the power meter 5 while relatively rotating the measurement optical fibers 32 and 42 and the optical fiber 100 to be measured (fourth step S4). In the present embodiment, the rotating means 34 and 44 rotate the measurement optical fibers 32 and 42 around the central axis. Here, when the optical axes of the peripheral cores 32b and 42b (or 32d and 42d) of the measurement optical fibers 32 and 42 and the peripheral core 102 (or 104) of the optical fiber 100 to be measured match, detection is performed by the power meter 5. Light intensity is maximized. Therefore, the rotation angle θ and the light intensity when the light intensity becomes maximum are recorded.

  It should be noted that the distance between the peripheral cores 102 (or 104) of the optical fiber 100 to be measured, the distance between the peripheral cores 32b (or 32d) of the optical fiber for measurement 32, and the peripheral core 42b (or 42d) of the optical fiber for measurement 42. The spacing between them is often known. Therefore, after measuring one peripheral core 102 (or 104), the optical axes of the other peripheral cores can be easily adjusted by rotating the measurement optical fibers 32 and 42 by an angle corresponding to the interval. Further, the above-described fourth step S4 can be automatically performed by automating the rotating means 34 and 44 and interlocking with the output value of the power meter 5.

  The effects obtained by the optical fiber measurement device 1A and the optical fiber measurement method of the present embodiment described above will be described.

  In a multi-core optical fiber, it is desired that more cores be arranged in a clad having a circular cross section as long as optical characteristics such as crosstalk between the cores are allowed. Therefore, it is effective that the core arrangement of the multi-core optical fiber is an axis object as shown in FIG. That is, it is preferable that the multi-core optical fiber includes a central core 101 and a peripheral core 102 (or 104) arranged on the axis as shown in FIG.

  When measuring the optical characteristics (loss, etc.) of each core of such a multi-core optical fiber, it is necessary to connect one end of each core to a light source and connect the other end to a photodetector. However, since existing light sources and photodetectors are designed on the assumption that a single-core optical fiber is connected to the light source and the photodetector, it is difficult to directly connect to the multi-core optical fiber. Therefore, the present inventor considered that each core is connected to one end side of the single mode optical fiber on the end face of the multi-core optical fiber, and the other end side of the single mode optical fiber is connected to a light source or a photodetector. In this case, there is a method of connecting each core of a multi-core optical fiber and a single mode optical fiber by using an alignment device having a multi-axis stage, etc., but the apparatus is large-scale and the alignment operation becomes complicated. .

  With respect to such problems, in the optical fiber measurement device 1A and the optical fiber measurement method according to the present embodiment, the optical fiber 100 to be measured, which is a multi-core optical fiber, is measured using the optical fiber measurement module 3. The optical fiber measurement module 3 includes a measurement optical fiber 32 having the same cross-sectional structure as the optical fiber 100 to be measured, and a single optically coupled to the peripheral core 32b (or 32d) at one end face of the measurement optical fiber 32. Mode optical fiber 31. Then, the measurement optical fiber 32 is arranged coaxially with the optical fiber 100 to be measured, and the measurement optical fiber 32 and the optical fiber 100 to be measured are rotated relative to each other, whereby the peripheral core 102 (or the optical fiber 100 to be measured) (or 104) can be easily made incident with measurement light. Thus, according to the optical fiber measurement device 1A and the optical fiber measurement method according to the present embodiment, the optical characteristics of the optical fiber 100 to be measured having the peripheral core 102 (or 104) at a position away from the central axis can be easily measured. It becomes possible to do.

  Further, as shown in FIG. 7, the support means 33 may have a groove 33 a having a V-shaped cross section for accommodating the measurement optical fiber 32 and the measured optical fiber 100. Alternatively, as shown in FIG. 8, the support means 33 may have a substantially cylindrical split sleeve 39 into which the holding members 38 and 110 can be inserted from both ends. By having one of these configurations, the support means 33 allows the measurement optical fiber 32 and the measured optical fiber 32 and the measured optical fiber 32 and the measured optical fiber 100 so that the other end surface of the measurement optical fiber 32 and the one end surface of the measured optical fiber 100 face each other coaxially. The measurement optical fiber 100 can be suitably supported.

  In the present embodiment, the optical fiber 32 for measurement is rotated and aligned while the light intensity is detected by the power meter 5, and then the power meter 5 is maintained in the state where the rotation angle of the optical fiber for measurement 32 is maintained. Instead, by using another optical measuring instrument, optical characteristics other than the loss of the optical fiber 100 to be measured can be easily measured.

  Further, the optical fiber measurement modules 3 and 4 according to the present embodiment are easily manufactured as follows, for example. First, a multi-core optical fiber having the same cross-sectional structure as the measured optical fiber is prepared. At both end faces of the multi-core optical fiber, one of a plurality of peripheral cores and a single mode optical fiber are aligned and coupled. Finally, by cutting the multi-core optical fiber, two optical fiber measuring modules 3 and 4 are completed.

(Second Embodiment)
FIG. 12 is a diagram schematically showing an overall configuration of an optical fiber measurement device 1B according to the second embodiment of the present invention. The difference between the optical fiber measurement device 1B of the present embodiment and the optical fiber measurement device 1A of the first embodiment is the configuration of the light detection means. The optical fiber measurement device 1B includes a light detection unit 7 instead of the light detection unit 6 of the first embodiment. The configuration other than the light detection means 7 in the optical fiber measurement device 1B is the same as that of the first embodiment.

  The light detection means 7 is optically coupled to the other end face of the optical fiber 100 to be measured (see FIG. 2), and is used for measurement emitted from the plurality of peripheral cores 102 (or 104) of the optical fiber 100 to be measured. Detects light intensity in a batch. The light detection means 7 of this embodiment includes a large-diameter optical fiber 11 whose one end face is optically coupled to the other end face of the optical fiber 100 to be measured, and a power meter 5 optically coupled to the other end face of the large-diameter optical fiber 11. Have

  FIG. 13 is a side cross-sectional view showing the large-diameter optical fiber 11 and the optical fiber 100 to be measured that are arranged to face each other. As shown in FIG. 13, the one end face 11 a of the large-diameter optical fiber 11 and the other end face 100 a of the optical fiber 100 to be measured are arranged to face each other. The large-diameter optical fiber 11 has a single core 11b and a clad 11c that covers the core 11b. The core 11b has a thickness that includes all of the plurality of peripheral cores 102 (or 104) of the optical fiber 100 to be measured. Therefore, the core 11b of the large-diameter optical fiber 11 is optically coupled to all of the plurality of peripheral cores 102 (or 104) of the optical fiber 100 to be measured. As such a large-diameter optical fiber 11, for example, a multimode optical fiber is suitable. A holding member 12 is provided at one end of the large-diameter optical fiber 11. The holding member 12 has the same configuration and material as the holding member 110 of the optical fiber 100 to be measured and the holding member 38 of the measurement optical fiber 32.

  The operation of the optical fiber measurement device 1B and the optical fiber measurement method according to the present embodiment are as follows. First, a single mode optical fiber 31, a measurement optical fiber 32 having the same structure as the measured optical fiber 100, and a large-diameter optical fiber 11 are prepared. These optical fibers 11, 31, and 32 are mounted on a fiber array or a glass capillary, and each end face is polished. Thereafter, for example, as shown in FIG. 6, one end of the single core 31 a of the single mode optical fiber 31 and the peripheral core 32 b (or 32 d) of the measurement optical fiber 32 are connected to one end of the measurement optical fiber 32. Are aligned and optically coupled, and then bonded and fixed (corresponding to the first step S1 in FIG. 9).

  Next, the measurement optical fiber 32 and the measured optical fiber 100 are supported so that the other end surface of the measurement optical fiber 32 and the one end surface of the measured optical fiber 100 are coaxially opposed. Further, the large-diameter optical fiber 11 and the measured optical fiber 100 are supported so that one end face of the large-diameter optical fiber 11 and the other end face of the measured optical fiber 100 are coaxially opposed (second step S2 in FIG. 9). Equivalent). At this time, there is quartz matching between the other end face of the measurement optical fiber 32 and one end face of the optical fiber 100 to be measured, and between one end face of the large-diameter optical fiber 11 and the other end face of the optical fiber 100 to be measured. Apply oil.

  Subsequently, measurement light is incident from the light source 2 to the other end of the single core 31a of the single mode optical fiber 31 (corresponding to the third step S3 in FIG. 9). This light passes through the single core 31 a of the single mode optical fiber 31 and the peripheral core 32 b (or 32 d) of the measurement optical fiber 32, and enters the peripheral core 102 (or 104) at one end face of the optical fiber 100 to be measured. . After passing through the peripheral core 102 (or 104), the light is emitted from the peripheral core 102 (or 104) at the other end face of the optical fiber 100 to be measured, and the power meter 5 passes through the core 11b of the large-diameter optical fiber 11. To reach.

  Subsequently, the intensity of light is detected by the power meter 5 while rotating the measurement optical fiber 32 and the measured optical fiber 100 relatively (corresponding to the fourth step S4 in FIG. 9). In the present embodiment, the rotating means 34 rotates the measurement optical fiber 32 around the central axis. Here, when the optical axes of the peripheral core 32b (or 32d) of the measurement optical fiber 32 and the peripheral core 102 (or 104) of the optical fiber 100 to be measured match, the light intensity detected by the power meter 5 is maximum. It becomes. Therefore, the rotation angle θ and the light intensity when the light intensity becomes maximum are recorded.

  Also in the present embodiment, the measurement optical fiber 32 is arranged coaxially with the optical fiber 100 to be measured, and the measurement optical fiber 32 and the optical fiber 100 to be measured are relatively rotated, so that the periphery of the optical fiber 100 to be measured is obtained. Measurement light can be easily incident on the core 102 (or 104). Therefore, it is possible to easily measure the optical characteristics of the measured optical fiber 100 having the peripheral core 102 (or 104) at a position away from the central axis.

(Third embodiment)
FIG. 14 is a diagram schematically showing an overall configuration of an optical fiber measurement device 1C according to the third embodiment of the present invention. The difference between the optical fiber measurement device 1C of the present embodiment and the optical fiber measurement device 1A of the first embodiment is the configuration of the light detection means. The optical fiber measurement device 1C includes a light detection unit 8 instead of the light detection unit 6 of the first embodiment. The configuration other than the light detection means 8 in the optical fiber measurement apparatus 1C is the same as that in the first embodiment.

  The light detection means 8 is optically coupled to the other end face of the optical fiber 100 to be measured (see FIG. 2), and is used for measurement emitted from the plurality of peripheral cores 102 (or 104) of the optical fiber 100 to be measured. Detects light intensity in a batch. The light detection means 8 of this embodiment has a photodiode 13. FIG. 15 is a side cross-sectional view showing a configuration in the vicinity of the light detection means 8. As shown in the figure, the light receiving surface 13a of the photodiode 13 is engineeringly coupled to the peripheral cores 102 (104) of the other end surface 100a by facing the other end surface 100a of the optical fiber 100 to be measured. ing.

  In this optical fiber measurement device 1C, the intensity of light emitted from the plurality of peripheral cores 102 (104) is detected by the photodiode 13 in the same manner as the measurement method according to the second embodiment described above. That is, also in this embodiment, the measurement optical fiber 32 is arranged coaxially with the measured optical fiber 100, and the measurement optical fiber 100 and the measured optical fiber 100 are relatively rotated, whereby the measured optical fiber 100 is measured. Measurement light can be easily incident on the peripheral core 102 (or 104). Therefore, it is possible to easily measure the optical characteristics of the measured optical fiber 100 having the peripheral core 102 (or 104) at a position away from the central axis.

  The optical fiber measurement module, the optical fiber measurement device, and the optical fiber measurement method according to the present invention are not limited to the above-described embodiments, and various other modifications are possible. For example, in each of the above embodiments, a multicore optical fiber having a central core and a plurality of peripheral cores is given as an example of the optical fiber to be measured and the optical fiber for measurement. The configuration is not limited to this.

  For example, the optical fiber 100C to be measured shown in FIG. 16A has only the four peripheral cores 102, with no central core disposed on the fiber central axis C1. Further, the optical fiber 100D to be measured shown in FIG. 16B has only the six peripheral cores 104 without the central core disposed on the fiber central axis C1. According to the optical fiber measurement module, the optical fiber measurement device, and the optical fiber measurement method according to the present invention, only the peripheral core arranged at a predetermined distance from the central axis is used as the optical fiber to be measured and the measurement light. Even if the fiber has, the optical characteristics can be easily measured. The number of peripheral cores is not limited to a plurality, and may be only one.

  In each of the above-described embodiments, the measurement optical fiber and the measurement optical fiber have the same cross-sectional structure, but the measurement optical fiber may have a cross-sectional structure different from that of the measurement optical fiber. . For example, even if the measurement optical fiber has only one peripheral core that is optically coupled to the single core of the single mode optical fiber, and the measured optical fiber has a plurality of peripheral cores, By rotating the optical fiber and the optical fiber to be measured relatively, one peripheral core of the optical fiber for measurement can be sequentially optically coupled to a plurality of peripheral cores of the optical fiber to be measured. The optical properties of the fiber can be measured easily.

  DESCRIPTION OF SYMBOLS 1A, 1B, 1C ... Optical fiber measuring apparatus, 2 ... Light source, 3, 4 ... Module for optical fiber measurement, 5 ... Power meter, 6, 7, 8 ... Light detection means, 11 ... Large diameter optical fiber, 12, 35 , 36, 38 ... holding member, 13 ... photodiode, 31 ... single mode optical fiber, 32 ... measuring optical fiber, 32, 42 ... measuring optical fiber, 33, 43 ... supporting means, 34, 44 ... rotating means, 37 ... Adhesive layer, 39 ... Split sleeve, 41 ... Single mode optical fiber, 42 ... Measuring optical fiber, 100 ... Optical fiber to be measured

Each of the rotating means 34 and 44 relatively rotates the measurement optical fibers 32 and 42 and the optical fiber 100 to be measured. In the present embodiment, the rotating means 34 and 44 rotate the measurement optical fibers 32 and 42 around the central axis, respectively. Each of the rotation means 34 and 44 has a configuration capable of precisely controlling the rotation angle of each of the measurement optical fibers 32 and 42. Such a configuration is realized, for example, by gripping the side surface of the measurement optical fiber 32 (42) and rotating the measurement optical fiber 32 (42) by an arbitrary angle by a stepping motor. As such rotating means 34 and 44, for example, an optical fiber rotating stage (such as F S 266 manufactured by Suruga Seiki) is suitable.

Claims (20)

An optical fiber to be measured having a first core and a first clad covering the first core, the central axis of the first core being separated from the central axis of the first clad by a predetermined distance An optical fiber measurement module used for measuring optical characteristics,
A single-mode optical fiber having a second core and a second cladding covering the second core, the second core being disposed on a central axis of the second cladding;
A third core and a third clad covering the third core, the central axis of the third core being separated from the central axis of the third clad by the predetermined distance, A measurement optical fiber in which a third core is optically coupled to one end of the second core;
Support means for supporting the measurement optical fiber and the measured optical fiber so that the other end surface of the measurement optical fiber and one end surface of the measured optical fiber are coaxially opposed to each other;
An optical fiber measuring module comprising: a rotating means for relatively rotating the measuring optical fiber and the optical fiber to be measured.   2. The optical fiber measurement module according to claim 1, wherein the supporting means has a groove having a V-shaped cross section for accommodating the measurement optical fiber and the optical fiber to be measured.   The support means includes a substantially cylindrical sleeve into which a substantially columnar holding member attached to each end of the measurement optical fiber and the optical fiber to be measured can be inserted from both ends, The optical fiber measurement module according to claim 1. The optical fiber to be measured and the optical fiber for measurement each have a plurality of the first and third cores,
The optical fiber measurement module according to any one of claims 1 to 3, wherein the first cores and the third cores are arranged at a predetermined interval. An optical fiber to be measured having a first core and a first clad covering the first core, the central axis of the first core being separated from the central axis of the first clad by a predetermined distance An optical fiber measuring device for measuring optical characteristics,
A first single-mode optical fiber having a second core and a second cladding covering the second core, wherein the second core is disposed on a central axis of the second cladding;
A third core and a third clad covering the third core, the central axis of the third core being separated from the central axis of the third clad by the predetermined distance, A first optical fiber for measurement in which a third core is optically coupled to one end of the second core;
First supporting means for supporting the first optical fiber for measurement and the optical fiber to be measured so that the other end face of the first optical fiber for measurement and the one end face of the optical fiber to be measured are coaxially opposed to each other. When,
First rotating means for relatively rotating the first measuring optical fiber and the measured optical fiber;
A light source that makes light incident on the other end of the second core of the first single-mode optical fiber;
An optical fiber measuring device comprising: a light detecting means for detecting the intensity of the light emitted from the first core at the other end surface of the optical fiber to be measured.   6. The optical fiber measurement device according to claim 5, wherein the first support means has a groove having a V-shaped cross section for accommodating the first optical fiber for measurement and the optical fiber to be measured. .   The first support means has a substantially cylindrical sleeve into which a substantially cylindrical holding member attached to each end of the first measurement optical fiber and the measured optical fiber can be inserted from both ends. The optical fiber measuring device according to claim 5, wherein: The optical fiber to be measured and the first optical fiber for measurement each include a plurality of the first and third cores;
The optical fiber measuring device according to any one of claims 5 to 7, wherein the first cores and the third cores are arranged at a predetermined interval.   The light detection means includes a light detection section that is optically coupled to the other end face of the optical fiber to be measured and collectively detects the intensity of the light emitted from the plurality of first cores. The optical fiber measuring device according to claim 8.   The light detection unit includes a large-diameter optical fiber having a core having a thickness including all of the plurality of first cores of the optical fiber to be measured, and the light emitted from the plurality of first cores The optical fiber measuring apparatus according to claim 9, wherein the intensity of the optical fiber is detected through the large-diameter optical fiber.   The light detection unit includes a photodiode optically coupled to the other end surface of the optical fiber to be measured, and the photodiode detects the intensity of the light emitted from the plurality of first cores. The optical fiber measuring device according to claim 9, wherein The light detecting means is
A second single-mode optical fiber having a fourth core and a fourth cladding covering the fourth core, wherein the fourth core is disposed on a central axis of the fourth cladding;
A fifth core and a fifth clad covering the fifth core, the central axis of the fifth core being separated from the central axis of the fifth clad by the predetermined distance, A second measurement optical fiber in which a fifth core is optically coupled to one end of the fourth core;
Second supporting means for supporting the second measuring optical fiber and the measured optical fiber so that the other end surface of the second measuring optical fiber and the other end surface of the measured optical fiber are coaxially opposed to each other. When,
A second rotating means for relatively rotating the second measuring optical fiber and the measured optical fiber;
The intensity of the light emitted from the plurality of first cores is detected through the second measurement optical fiber and the second single mode optical fiber. The optical fiber measuring device according to any one of the above. An optical fiber to be measured having a first core and a first clad covering the first core, the central axis of the first core being separated from the central axis of the first clad by a predetermined distance A method for measuring optical properties comprising:
The first single-mode optical fiber having a second core and a second clad covering the second core, wherein the second core is disposed on a central axis of the second clad. One end of the second core, a third core, and a third clad covering the third core, the central axis of the third core being the predetermined distance from the central axis of the third clad A first step of optically coupling the third core of the first measurement optical fiber that is separated at one end face of the first measurement optical fiber;
A second step of supporting the first measurement optical fiber and the measured optical fiber so that the other end surface of the first measurement optical fiber and one end surface of the measured optical fiber are coaxially opposed to each other;
A third step in which light is incident on the other end of the second core of the first single-mode optical fiber;
A fourth detecting the intensity of the light emitted from the first core at the other end face of the optical fiber under measurement while relatively rotating the optical fiber for measurement and the optical fiber under measurement. An optical fiber measurement method.   14. The optical fiber measurement method according to claim 13, wherein, in the second step, the first measurement optical fiber and the optical fiber to be measured are accommodated in a groove having a V-shaped cross section.   In the second step, a substantially columnar holding member attached to each end of the measurement optical fiber and the optical fiber to be measured is inserted into both ends of a substantially cylindrical sleeve. The optical fiber measuring method according to claim 13. The optical fiber to be measured and the first optical fiber for measurement each include a plurality of the first and third cores;
The optical fiber measurement method according to any one of claims 13 to 15, wherein the first cores and the third cores are arranged at a predetermined interval.   The intensity of the light emitted from a plurality of the first cores is collectively detected at the other end face of the optical fiber to be measured in the fourth step. Optical fiber measurement method.   In the fourth step, the large diameter has a core having a thickness that includes all of the plurality of first cores of the optical fiber to be measured with respect to the intensity of the light emitted from the plurality of first cores. The optical fiber measurement method according to claim 17, wherein detection is performed via an optical fiber.   In the fourth step, the intensity of the light emitted from the plurality of first cores is detected by a photodiode optically coupled to the other end surface of the optical fiber to be measured. The optical fiber measuring method according to claim 17. In the first step, a fourth core and a fourth clad covering the fourth core are provided, and the fourth core is disposed on the central axis of the fourth clad. One end of the fourth core of the single-mode optical fiber, a fifth core, and a fifth clad covering the fifth core, the central axis of the fifth core being the fifth core Optically coupling the fifth core of the second measurement optical fiber that is separated from the central axis of the clad by the predetermined distance at one end face of the second measurement optical fiber;
In the second step, the second measuring optical fiber and the measured optical fiber are coaxially opposed to the other end surface of the second measuring optical fiber and the other end surface of the measured optical fiber. Support
During the fourth step, the light is emitted from the other end of the fourth core of the second single mode optical fiber while relatively rotating the second measurement optical fiber and the optical fiber to be measured. The optical fiber measurement method according to claim 13, wherein the intensity of the light is detected.

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