Fusion splicing device and fusion splicing method

Abstract

A fusion splicing device according to one embodiment comprises a rotation mechanism (20) that causes a first multicore fiber (F11) and a second multicore fiber (F21) to rotate, a first microscope (32b) that receives light emitted from a first light source (31b) along a first direction to observe the first multicore fiber (F11) and the second multicore fiber (F21), a second microscope (32b) that receives light emitted from a second light source (31c) along a second direction to observe the first multicore fiber (F11) and the second multicore fiber (F21), and a calculation unit (33) that calculates an estimation loss from an image of the first multicore fiber (F11) and the second multicore fiber (F21) acquired by the first microscope (32b) and an image of the first multicore fiber (F11) and the second multicore fiber (F21) acquired by the second microscope (32c).

Description

Fusion splicer and fusion splicing method

[0001] This application claims priority to Japanese Patent Application No. 2023-223130 filed on December 28, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] Patent Document 1 describes a method for estimating the splice loss of optical fibers. In this splice loss estimation method, a single-mode optical fiber in which four-fiber ribbons are fusion-spliced ​​together is measured using a power monitoring method. In this method, the amount of axial misalignment is measured immediately before and after heat fusion, and then again after heating is completed. The estimated loss is calculated from the difference between these amounts of axial misalignment. Non-Patent Document 1 describes a method for estimating the splice loss of optical fibers using the Marcuse loss formula from the outer dimensions of the optical fiber.

[0003] Patent Document 2 describes a fusion splicer. The fusion splicer includes an optical fiber holder that holds an optical fiber, a rotation mechanism that rotates the optical fiber, a bending unit that bends the optical fiber, a light source that introduces light from the side of the optical fiber, and a power supply unit that supplies power to the light source. The bending unit and the light source are located either closer to the tip of the optical fiber than the optical fiber holder, or in the optical fiber holder or the rotation mechanism.

[0004] Patent Document 3 describes a method for fusion splicing optical fibers. In this fusion splicing method, the optical fibers to be spliced ​​are arranged at a predetermined interval, preheated by aerial discharge, and then heated. The shape of the fusion spliced ​​cores is imaged and subjected to image processing. The splice loss is estimated from the data obtained as a result of image processing using FD-BPM (Differential Beam Propagation Method). In FD-BPM, the data is compared with a database created in advance.

[0005] JP-A-1-196531 International Publication No. 2022 / 244843 JP-A-9-138318

[0006] D. Marcuse, "Loss Analysis of Single-Mode Fiber Splices", The Bell System Technical Journal, Vol.56,No.5, pp.703-718 1977.

[0007] A fusion splicer according to the present disclosure fusion-splices together a first multicore fiber having a plurality of first cores exposed at a first end face and a second multicore fiber having a plurality of second cores exposed at a second end face, the fusion splicer including: a rotation mechanism that rotates the fusion-spliced ​​first multicore fiber and the second multicore fiber, a first microscope that observes the first multicore fiber and the second multicore fiber by receiving light emitted from a first light source to the first multicore fiber and the second multicore fiber along a first direction, a second microscope that observes the first multicore fiber and the second multicore fiber by receiving light emitted from the second light source to the first multicore fiber and the second multicore fiber along a second direction intersecting the first direction, and a calculation unit that calculates an estimated loss from images of the first multicore fiber and the second multicore fiber acquired by the first microscope and the images of the first multicore fiber and the second multicore fiber acquired by the second microscope.

[0008] FIG. 1 is a diagram showing a schematic configuration of a fusion splicer according to an embodiment. FIG. 2 is a diagram schematically showing a first multicore fiber and a second multicore fiber. FIG. 3 is a diagram showing an observation mechanism for a multicore fiber in the fusion splicer according to an embodiment. FIG. 4 is a diagram showing an image of a multicore fiber acquired by a microscope of the fusion splicer according to an embodiment. FIG. 5 is a diagram for explaining an axial misalignment amount and an angular misalignment amount. FIG. 6 is a diagram showing a light source, a multicore fiber, and a microscope in the observation mechanism of FIG. 3. FIG. 7 is a diagram showing a state in which the multicore fiber is rotated and the microscope is moved in the observation mechanism of FIG. 3. FIG. 8 is a flowchart showing an example of steps of a fusion splicing method according to an embodiment.

[0009] A known method for calculating an estimated loss in an optical fiber is to observe the optical fiber from different directions using two microscopes to measure core positions and calculate the estimated loss. However, if the optical fiber is a multi-core fiber, when observing the optical fiber using a microscope, multiple cores of the optical fiber may overlap when viewed from the microscope. In this case, it may be impossible to observe multiple cores simultaneously using two microscopes. If multiple cores cannot be observed simultaneously using two microscopes, the calculation accuracy of the estimated loss of the multi-core fiber may decrease. Therefore, there is room for improvement in the calculation accuracy of the estimated loss in a multi-core fiber.

[0010] An object of the present disclosure is to provide a fusion splicer and a fusion splicing method that can calculate an estimated loss in a multicore fiber with high accuracy.

[0011] According to the present disclosure, it is possible to calculate an estimated loss in a multicore fiber with high accuracy.

[0012] [Description of Embodiments of the Present Invention] First, embodiments of a fusion splicer and a fusion splicing method according to the present disclosure will be listed and described. (1) A fusion splicer according to one embodiment fusion-splices a first multicore fiber having a plurality of first cores exposed at a first end face and a second multicore fiber having a plurality of second cores exposed at a second end face to each other. the fusion splicer includes a rotation mechanism that rotates the first multicore fiber and the second multicore fiber that are fusion-spliced ​​to each other, a first microscope that observes the first multicore fiber and the second multicore fiber by receiving light emitted from a first light source to the first multicore fiber and the second multicore fiber along a first direction, a second microscope that observes the first multicore fiber and the second multicore fiber by receiving light emitted from a second light source to the first multicore fiber and the second multicore fiber along a second direction intersecting the first direction, and a calculation unit that calculates an estimated loss from images of the first multicore fiber and the second multicore fiber acquired by the first microscope and the images of the first multicore fiber and the second multicore fiber acquired by the second microscope. The term "image" includes not only something configured as an image but also a data collection including position information, brightness information, color information, etc. that form the basis of the image.

[0013] (6) A fusion splicing method according to one embodiment includes the steps of: rotating the first multicore fiber having a plurality of first cores exposed at a first end face to a second multicore fiber having a plurality of second cores exposed at a second end face; observing the first multicore fiber and the second multicore fiber with a first microscope by receiving light emitted to the first multicore fiber and the second multicore fiber along a first direction; observing the first multicore fiber and the second multicore fiber with a second microscope by receiving light emitted to the first multicore fiber and the second multicore fiber along a second direction intersecting the first direction; and calculating an estimated loss from images of the first multicore fiber and the second multicore fiber acquired by the first microscope and images of the first multicore fiber and the second multicore fiber acquired by the second microscope.

[0014] The fusion splicer and fusion splicing method include a rotation mechanism, a first microscope, a second microscope, and a calculation unit. The first microscope receives light emitted along a first direction to observe the first multicore fiber and the second multicore fiber fusion-spliced ​​to each other, and the second microscope receives light emitted along a second direction to observe the first multicore fiber and the second multicore fiber fusion-spliced ​​to each other. When observing the first multicore fiber and the second multicore fiber with the first microscope and the second microscope, the first multicore fiber and the second multicore fiber can be rotated by the rotation mechanism. Therefore, the first multicore fiber and the second multicore fiber can be observed in a state where they are rotated to a position where the first cores and the second cores can be detected as seen from the first microscope and a position where the first cores and the second cores can be detected as seen from the second microscope. Therefore, the calculation unit can calculate the estimated loss with high accuracy from the images of the first multicore fiber and the second multicore fiber acquired by the first microscope and the images of the first multicore fiber and the second multicore fiber acquired by the second microscope.

[0015] (2) In the above (1), the rotation mechanism may rotate the first multicore fiber and the second multicore fiber until either the first microscope or the second microscope can observe the multiple first cores and the multiple second cores. In this case, the estimated loss can be calculated with higher accuracy from images of the first multicore fiber and the second multicore fiber.

[0016] (3) In the above (1), the rotation mechanism may rotate the first multicore fiber and the second multicore fiber until both the first microscope and the second microscope can observe one first core and one second core. In this case, the estimated loss can be calculated with higher accuracy from images of the first multicore fiber and the second multicore fiber.

[0017] (4) In any of the above (1) to (3), the first microscope may acquire an image of the first multicore fiber or the second multicore fiber with its focus position shifted from a plane that is perpendicular to the optical axis of the first microscope and includes the central axis of the first multicore fiber or the second multicore fiber. Alternatively, the second microscope may acquire an image of the first multicore fiber or the second multicore fiber with its focus position shifted from a plane that is perpendicular to the optical axis of the second microscope and includes the central axis of the first multicore fiber or the second multicore fiber. In this case, the accuracy of identifying the position of the first core or the second core in the acquired image is improved.

[0018] (5) In any of the above (1) to (4), the calculation unit may calculate the estimated loss from an axial misalignment, which is the amount of misalignment of the axis of the second core with respect to the axis of the first core, an angular misalignment, which is the amount of misalignment of the extending direction of the second core at the second end face with respect to the extending direction of the first core at the first end face, the mode field diameter of the first core, and the mode field diameter of the second core. In this case, the calculation of the estimated loss can be performed with higher accuracy.

[0019] [Details of the embodiment of the present disclosure] Specific examples of a fusion splicer and a fusion splicing method according to the embodiment will be described. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and redundant explanations will be omitted as appropriate. The drawings may be partially simplified or exaggerated to facilitate understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0020] The configuration of a fusion splicer according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram for explaining an overview of the fusion splicer 1 according to this embodiment. As shown in Fig. 1, the fusion splicer 1 fusion-splices a pair of optical fibers F together. The fusion splicer 1 has an optical fiber holder 10 having a V-groove 11, and a rotation mechanism 20 that rotates the optical fiber holder 10. The axes of the pair of optical fibers F coincide with each other. The "axis" refers to the center line of the optical fiber that passes through the center of the optical fiber and extends along the direction in which the optical fiber extends.

[0021] The optical fiber holder 10 and the rotation mechanism 20 are aligned along the axial direction, which is the direction in which the axis of the optical fiber F extends. When an XYZ three-dimensional Cartesian coordinate system is set and the axis of the optical fiber F is defined as the Z axis, the axial direction of the optical fiber F is the Z axis direction. The fusion splicer 1 includes a pair of optical fiber holders 10 aligned along the Z axis direction, which is the direction in which each of the pair of optical fibers F extends, and a pair of rotation mechanisms 20 aligned along the Z axis direction.

[0022] An optical fiber F to be fusion spliced ​​is positioned in the V-groove 11 of each optical fiber holder 10. The optical fiber holder 10 is made of metal, for example. The optical fiber holder 10 holds, for example, a coated portion of the optical fiber F. The optical fiber holder 10 holds the optical fiber F with the end face F1 of the optical fiber F protruding in the Z-axis direction. The rotation mechanism 20 is disposed on the opposite side of the optical fiber holder 10 from the end face F1 of the optical fiber F.

[0023] A pair of discharge electrodes 2 are arranged at positions where the end faces F1 of the pair of optical fibers F face each other. The pair of discharge electrodes 2 are arranged at positions facing each other along a direction (e.g., the X-axis direction) intersecting the optical fibers F. The optical fiber holder 10 has, for example, a base 12 on which the optical fibers F are placed and on which a V-groove 11 extending along the Z-axis direction is formed, and a lid 13 placed on the base 12. The base 12 and the lid 13 are arranged, for example, to be aligned along the Y-axis direction that intersects both the X-axis direction and the Z-axis direction.

[0024] The pair of discharge electrodes 2 fusion-splices the end faces F1 of the pair of optical fibers F by electric discharge. The fusion splicer 1 has a control unit 3 that controls each part of the fusion splicer 1. The control unit 3 controls the discharge current and discharge time of the discharge electrodes 2, thereby performing fusion splicing under fusion conditions suited to the type of optical fibers F. In the fusion splicer 1, the control unit 3 aligns the pair of optical fibers F.

[0025] The control unit 3 adjusts the position of each optical fiber F in the X-axis direction and the Y-axis direction, and also aligns the axes of the pair of optical fibers F so that the pair of optical fibers F are aligned in a straight line along the Z-axis direction. The control unit 3 aligns the pair of optical fibers F in the X-axis direction, the Y-axis direction, and the Z-axis direction. The control unit 3 controls the rotation mechanism 20 to rotate the optical fiber F around the axis of the optical fiber F (which is the same as the Z-axis in the drawing), thereby aligning it in the θ direction.

[0026] The optical fiber F is a multi-core fiber. The positions of the core, cladding, marker, etc. in the θ direction of the multi-core fiber need to be aligned with those of the multi-core fiber to be spliced. Fig. 2 shows an example of the optical fiber F to be fusion-spliced ​​by the fusion splicer 1. As shown in Fig. 2, the optical fiber F includes a first multi-core fiber F11 and a second multi-core fiber F21, and the fusion splicer 1 fusion-splices the first multi-core fiber F11 to the second multi-core fiber F21.

[0027] The first multicore fiber F11 has a plurality of first cores F12 exposed at a first end face F13, and the second multicore fiber F21 has a plurality of second cores F22 exposed at a second end face F23. Hereinafter, when there is no need to distinguish between the first multicore fiber F11 and the second multicore fiber F21, they may be collectively referred to as the optical fiber F.

[0028] The fusion splicer 1 is equipped with an observation mechanism for observing the pair of optical fibers F. Fig. 3 is a diagram showing an observation mechanism 30, which is an example of the observation mechanism of the fusion splicer 1. The observation mechanism 30 has a light source 31 and a microscope 32. The light source 31 includes a first light source 31b and a second light source 31c, and the microscope 32 includes a first microscope 32b and a second microscope 32c.

[0029] The first light source 31b is, for example, a light-emitting element such as a light-emitting diode. As an example, the first light source 31b emits red light L. The first microscope 32b includes, for example, an observation lens and an imaging element. For example, the first microscope 32b is a charge-coupled device camera (CCD camera) or a complementary metal oxide semiconductor camera (CMOS camera).

[0030] For example, the position of the first microscope 32b is variable. The observation result by the first microscope 32b is obtained, for example, as luminance information of the light L. The luminance information of the light L obtained by the first microscope 32b is output to the control unit 3. For example, the function and configuration of the second light source 31c are the same as the function and configuration of the first light source 31b, and the function and configuration of the second microscope 32c are the same as the function and configuration of the first microscope 32b.

[0031] The first light source 31b and the first microscope 32b are arranged side by side along the first direction D1, with the optical fiber F sandwiched therebetween. The second light source 31c and the second microscope 32c are arranged side by side along a second direction D2 intersecting the first direction D1, with the optical fiber F sandwiched therebetween. The angle formed between the first direction D1 and the second direction D2 is, for example, greater than 0° and less than 180°, or may be greater than or equal to 60° and less than or equal to 120° (90°, as an example). The first light source 31b emits light L to the first multicore fiber F11 and the second multicore fiber F21 along the first direction D1. The second light source 31c emits light L to the first multicore fiber F11 and the second multicore fiber F21 along the second direction D2.

[0032] The first microscope 32b observes the first multicore fiber F11 and the second multicore fiber F21 by receiving light L emitted from the first light source 31b to the first multicore fiber F11 and the second multicore fiber F21. The second microscope 32c observes the first multicore fiber F11 and the second multicore fiber F21 by receiving light L emitted from the second light source 31c to the first multicore fiber F11 and the second multicore fiber F21. The rotation mechanism 20 described above rotates the first multicore fiber F11 and the second multicore fiber F21 until both the first microscope 32b and the second microscope 32c can observe the multiple first cores F12 and the second cores F22.

[0033] The first microscope 32b acquires images of the first multicore fiber F11 and the second multicore fiber F21. For example, the first microscope 32b receives light L that has passed through the first multicore fiber F11 and the second multicore fiber F21 to obtain brightness information of the first multicore fiber F11 and the second multicore fiber F21.

[0034] Fig. 4 shows an example of a side observation image obtained by the first microscope 32b. As shown in Fig. 4, the side observation image shows the outer diameter B of the cladding of the optical fiber F and the area W where light is collected by the cladding of the optical fiber F. The image obtained by the second microscope 32c is performed in the same manner as the image obtained by the first microscope 32b.

[0035] 3 , the control unit 3 includes, for example, a calculation unit 33 that calculates an estimated loss of the optical fiber F, and a drive unit 34 that moves the first microscope 32 b and the second microscope 32 c. The estimated loss of the optical fiber F indicates, for example, an estimated value of the splice loss occurring between the first multicore fiber F11 and the second multicore fiber F21. The calculation unit 33 calculates the estimated loss from images of the first multicore fiber F11 and the second multicore fiber F21 acquired by the first microscope 32 b and images of the first multicore fiber F11 and the second multicore fiber F21 acquired by the second microscope 32 c.

[0036] For example, the first microscope 32b and the second microscope 32c acquire images of the first multi-core fiber F11 and the second multi-core fiber F21, respectively, after fusion splicing. If an image including the fusion spliced ​​portion of the first multi-core fiber F11 and the second multi-core fiber F21 near the center is acquired, images of both the first multi-core fiber F11 and the second multi-core fiber F21 can be acquired at once with one microscope. At this time, the calculation unit 33 calculates the estimated loss from the images of the first multi-core fiber F11 and the second multi-core fiber F21 that are fusion spliced ​​to each other.

[0037] 5 , the calculation unit 33 calculates an estimated loss for each core from the axial misalignment d and angular misalignment θ of the first multicore fiber F11 and the second multicore fiber F21, the mode field diameter of the first core F12, and the mode field diameter of the second core F22, based on the image M1 acquired by the first microscope 32b and the image M2 acquired by the second microscope 32c. The axial misalignment d indicates the misalignment of the axis of the second core F22 with respect to the axis of the first core F12. The angular misalignment θ is the misalignment of the extending direction of the second core F22 at the second end face F23 with respect to the extending direction of the first core F12 at the first end face F13.

[0038] For example, the calculation unit 33 calculates the estimated losses of the first multicore fiber F11 and the second multicore fiber F21 from the axial misalignment d, the angular misalignment θ, and the mode field diameter (MFD) mismatch. In this case, the calculation unit 33 calculates the estimated loss using, for example, the Marcuse formula described in the aforementioned Non-Patent Document 1. The mode field diameter mismatch indicates, for example, the difference between the mode field diameter of the first multicore fiber F11 and the mode field diameter of the second multicore fiber F21.

[0039] Acquiring an image of the optical fiber F and calculating the estimated loss will be described in more detail using Figures 6 and 7. Hereinafter, when there is no need to distinguish between the first core F12 and the second core F22, these may be collectively referred to as core F2. For example, as shown in Figure 6, when two cores F2 overlap on the optical path of light L from the second light source 31c, it may be difficult to simultaneously observe the two cores F2 using the first microscope 32b or the second microscope 32c. "Two cores overlap on the optical path" means, for example, that at least a portion of the two cores is aligned along the optical path of light from the light source.

[0040] 7, the rotation mechanism 20 rotates the optical fiber F to a position where the first microscope 32b and the second microscope 32c can each observe two cores F2. Note that the rotation mechanism 20 does not have to rotate the optical fiber F to a position where the first microscope 32b and the second microscope 32c can simultaneously observe two cores F2. The rotation mechanism 20 may rotate the optical fiber F to a rotation position where the first microscope 32b can observe two cores F2, and a rotation position where the second microscope 32c can observe two cores F2.

[0041] Alternatively, the rotation mechanism 20 may rotate the optical fiber F to each of the following positions: a rotation position where the first microscope 32b can observe the first core of the two cores F2; ​​a rotation position where the first microscope 32b can observe the second core of the two cores F2; ​​a rotation position where the second microscope 32c can observe the first core of the two cores F2; ​​and a rotation position where the second microscope 32c can observe the second core of the two cores F2. The rotation mechanism 20 may rotate the optical fiber F at fixed angle intervals, or may rotate the optical fiber F until the angle at which the core F2 is most easily viewed. For example, in the example of FIG. 7 , the rotation mechanism 20 rotates the optical fiber F by an angle A in the θ direction until the optical fiber F is positioned such that the two cores F2 do not overlap on the optical path of the light L from the first light source 31b and the two cores F2 do not overlap on the optical path of the light L from the second light source 31c.

[0042] The value of angle A may be stored in advance. Furthermore, the value of angle A may change each time an image is acquired by the first microscope 32b and the second microscope 32c. For example, angle A is equal to or greater than 40° and equal to or less than 50°. However, the value of angle A is not particularly limited. By rotating the optical fiber F as described above, both the first microscope 32b and the second microscope 32c can observe two cores F2 that are separated from each other.

[0043] The position at which the cores F2 are observed does not have to be a position at which the two cores F2 do not overlap at all. The position at which the cores F2 are observed needs only to be a rotational position at which one core F2 can be detected. By repeatedly acquiring images, confirming the detection, and changing the rotational position, it is sufficient if images of all or a specific number of the first cores F12 and the second cores F22 can be acquired by the first microscope 32b and the second microscope 32c. The "specific number of cores" refers to, for example, the number of cores required to calculate the worst-case or average value of the estimated loss for all or some of the cores. The "specific number of cores" refers to, for example, "a majority of the total number of cores included in one multicore fiber." Alternatively, the "specific number of cores" refers to "those with the worst linearity near the fusion splice among all the cores." It is also possible to "detect approximately half of the total number of cores included in one multicore fiber with the first microscope 32b, and detect the remaining cores with the second microscope 32c."

[0044] The drive unit 34 moves the first microscope 32b and the second microscope 32c, for example, by outputting drive signals to each of the first microscope 32b and the second microscope 32c. The drive unit 34 moves the first microscope 32b along the first direction D1 and moves the second microscope 32c along the second direction D2. For example, the drive unit 34 moves each of the first microscope 32b and the second microscope 32c toward or away from the optical fiber F. The drive unit 34 moves each of the first microscope 32b and the second microscope 32c so that the focus positions are aligned on a plane perpendicular to the optical axes of the first microscope 32b and the second microscope 32c and including the central axis of the optical fiber F. In this state, each of the first microscope 32b and the second microscope 32c acquires an image.

[0045] At this time, the core F2 may not be detected in the acquired image, which may affect the calculation of the estimated loss by the calculation unit 33. Therefore, the drive unit 34 moves each of the first microscope 32b and the second microscope 32c so that the focus position is shifted from a plane that is perpendicular to the optical axis of the microscope and that includes the central axis of the optical fiber F.

[0046] For example, the drive unit 34 moves the first microscope 32b and the second microscope 32c N μm (N is a real number) away from the optical fiber F from a position where the focus position coincides with a plane perpendicular to the optical axis of the microscope and including the central axis of the optical fiber F. The value of N may be stored in advance. The value of N may change each time an image is acquired by the first microscope 32b and the second microscope 32c. The drive unit 34 may move the first microscope 32b and the second microscope 32c closer to the optical fiber F. N is a positive value when moving away, and N is a negative value when moving closer.

[0047] If the cladding outer diameter of the optical fiber F is B μm (see FIG. 4 ), the absolute value of N may, for example, be greater than 0 and equal to or less than B, or greater than 0 and equal to or less than 65. The value of N may be a value when the inside-outside ratio calculated from the area W of the light collected by the cladding of the optical fiber F is greater than or equal to 20% and equal to or less than 80%. The inside-outside ratio is calculated as 100×W / B. The first microscope 32b and the second microscope 32c acquire images of the optical fiber F with their focus positions shifted from a plane perpendicular to the optical axis of the microscope and including the central axis of the optical fiber F. This allows a clearer image of the core F2 to be acquired.

[0048] The fusion splicing method according to this embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart showing an example of steps of the fusion splicing method according to the embodiment. An example of a method for performing fusion splicing and calculating an estimated loss using the fusion splicer 1 will be described below. First, the end faces F1 of a pair of optical fibers F are made to face each other. The first end face F13 of the first multicore fiber F11 is made to face the second end face F23 of the second multicore fiber F21.

[0049] Then, the rotation mechanism 20 rotates at least one of the first multicore fiber F11 and the first core F12 in the θ direction to perform rotational alignment. In the rotational alignment, the positions of the multiple first cores F12 of the first multicore fiber F11 in the θ direction are aligned with the positions of the multiple second cores F22 of the second multicore fiber F21 in the θ direction. Then, the discharge electrode 2 fusion-splices the first end face F13 of the first multicore fiber F11 to the second end face F23 of the second multicore fiber F21 (fusion-splicing process, step S1).

[0050] Next, the first multicore fiber F11 and the second multicore fiber F21 are rotated (rotating step, step S2). As described above, the rotation mechanism 20 rotates the first multicore fiber F11 and the second multicore fiber F21 until both the first microscope 32 b and the second microscope 32 c can observe the two cores F2.

[0051] After rotating the first multi-core fiber F11 and the second multi-core fiber F21, the first microscope 32b and the second microscope 32c observe the first multi-core fiber F11 and the second multi-core fiber F21, respectively, and acquire images (first microscope observation step, second microscope observation step, step S3).

[0052] The images of the first multicore fiber F11 and the second multicore fiber F21 acquired by the first microscope 32b and the images of the first multicore fiber F11 and the second multicore fiber F21 acquired by the second microscope 32c are output to the control unit 3. For example, the control unit 3 determines whether or not the first core F12 and the second core F22 have not been detected in the images output to the control unit 3 (step of determining whether or not they have not been detected, step S4). Whether or not they have not been detected can be determined based on, for example, brightness information in the images.

[0053] When the control unit 3 determines that both the first core F12 and the second core F22 have been detected, the control unit 3 proceeds to step S8. On the other hand, when the control unit 3 determines that either the first core F12 or the second core F22 has not been detected, the control unit 3 defocuses the first microscope 32b and the second microscope 32c (defocusing step, step S5). At this time, the drive unit 34 moves the first microscope 32b or the second microscope 32c so that the focus position is a position that is shifted from a plane that is perpendicular to the optical axis of the first microscope 32b or the second microscope 32c and includes the central axis of the optical fiber F. Then, the first microscope 32b and the second microscope 32c observe the first multicore fiber F11 and the second multicore fiber F21 to obtain images (first microscope observing step, second microscope observing step, step S6). Thereafter, the control unit 3 proceeds to step S7, where it is determined whether the first core F12 and the second core F22 have not been detected. If either the first core F12 or the second core F22 has not been detected, the process proceeds to step S5. These steps are repeated as many times as necessary until it is determined that both the first core F12 and the second core F22 have been detected. Then, when it is determined that both the first core F12 and the second core F22 have been detected, the process proceeds to step S8.

[0054] In step S8, the calculation unit 33 calculates an estimated loss from the images of the first multicore fiber F11 and the second multicore fiber F21 acquired by the first microscope 32b and the images of the first multicore fiber F11 and the second multicore fiber F21 acquired by the second microscope 32c (a step of calculating an estimated loss). For example, the calculation unit 33 calculates the estimated loss from the axial misalignment d and angular misalignment θ between the first multicore fiber F11 and the second multicore fiber F21, the mode field diameter of the first core F12, and the mode field diameter of the second core F22. Thereafter, a series of steps is completed.

[0055] The following describes the effects obtained from the fusion splicer 1 and fusion splicing method according to this embodiment. The fusion splicer 1 and fusion splicing method according to this embodiment include a rotation mechanism 20, a first microscope 32b, a second microscope 32c, and a calculation unit 33. The first microscope 32b receives light L emitted along a first direction D1 to observe the first multi-core fiber F11 and the second multi-core fiber F21 that are fusion spliced ​​to each other, and the second microscope 32c receives light L emitted in a second direction D2 to observe the first multi-core fiber F11 and the second multi-core fiber F21 that are fusion spliced ​​to each other. When the first multi-core fiber F11 and the second multi-core fiber F21 are observed by the first microscope 32b and the second microscope 32c, the first multi-core fiber F11 and the second multi-core fiber F21 can be rotated by the rotation mechanism 20.

[0056] Therefore, the first multicore fiber F11 and the second multicore fiber F21 can be observed in a state where the first microscope 32 b has rotated to a position where the first core F12 and the second core F22 can be detected, and the second microscope 32 c can detect the first core F12 and the second core F22. Therefore, the calculation unit 33 can calculate the estimated loss with high accuracy from the images of the first multicore fiber F11 and the second multicore fiber F21 acquired by the first microscope 32 b and the images of the first multicore fiber F11 and the second multicore fiber F21 acquired by the second microscope 32 c.

[0057] As described above, the rotation mechanism 20 may rotate the first multicore fiber F11 and the second multicore fiber F21 until either the first microscope 32 b or the second microscope 32 c can observe the multiple first cores F12 and the multiple second cores F22. In this case, the estimated loss can be calculated with higher accuracy from the images of the first multicore fiber F11 and the second multicore fiber F21.

[0058] As described above, the rotation mechanism 20 may rotate the first multicore fiber F11 and the second multicore fiber F21 until both the first microscope 32 b and the second microscope 32 c can observe one first core F12 and one second core F22. In this case, the estimated loss can be calculated with higher accuracy from images of the first multicore fiber F11 and the second multicore fiber F21.

[0059] As described above, the first microscope 32b may acquire an image of the first multi-core fiber F11 or the second multi-core fiber F21 with the focus position shifted from a plane that is perpendicular to the optical axis of the first microscope 32b and that includes the central axis of the first multi-core fiber F11 or the second multi-core fiber F21. Alternatively, the second microscope 32c may acquire an image of the first multi-core fiber F11 or the second multi-core fiber F21 with the focus position shifted from a plane that is perpendicular to the optical axis of the second microscope 32c and that includes the central axis of the first multi-core fiber F11 or the second multi-core fiber F21. In this case, the images of the first core F12 and the second core F22 can be acquired more clearly. As a result, the accuracy of identifying the position of the first core or the second core in the acquired image is improved.

[0060] As described above, the calculation unit 33 may calculate the estimated loss from the axial misalignment d, which is the amount of misalignment of the axis of the second core F22 with respect to the axis of the first core F12, the angular misalignment θ, which is the amount of misalignment of the extending direction of the second core F22 at the second end face F23 with respect to the extending direction of the first core F12 at the first end face F13, the mode field diameter of the first core F12, and the mode field diameter of the second core F22. In this case, the calculation of the estimated loss can be performed with higher accuracy.

[0061] The above describes embodiments of the fusion splicer and fusion splicing method according to the present disclosure. However, the present invention is not limited to the above-described embodiments. In other words, those skilled in the art will readily recognize that various modifications and variations of the present invention are possible within the spirit and scope of the claims. The configuration of each part of the fusion splicer and the steps of the fusion splicing method can be modified as appropriate within the spirit and scope of the above-described embodiments. In other words, the configuration, shape, size, number, materials, and arrangement of each part of the fusion splicer, as well as the content and order of the steps of the fusion splicing method, are not limited to the above-described embodiments and can be modified as appropriate.

[0062] For example, in the above-described embodiment, an example has been described in which defocusing is performed by moving each of the first microscope 32b and the second microscope 32c so that the focus position is shifted from a plane perpendicular to the optical axis of the first microscope 32b or the second microscope 32c and including the central axis of the optical fiber F. However, defocusing does not have to be performed. In this case, it is possible to further shorten the time required for fusion splicing.

[0063] In the above-described embodiment, an example has been described in which a first multicore fiber F11 having two first cores F12 is fusion-spliced ​​to a second multicore fiber F21 having two second cores F22. However, the number of cores in the first multicore fiber and the second multicore fiber may be three or more and can be changed as appropriate.

[0064] REFERENCE SIGNS LIST 1... Fusion splicer 2... Discharge electrode 3... Control unit 10... Optical fiber holder 11... V-groove 12... Base 13... Cover 20... Rotation mechanism 30... Observation mechanism 31... Light source 31b... First light source 31c... Second light source 32... Microscope 32b... First microscope 32c... Second microscope 33... Calculation unit 34... Driving unit A... Angle F... Optical fiber F1... End face F2... Core F11... First multi-core fiber F12... First core F13... First end face F21... Second multi-core fiber F22... Second core F23... Second end face L... Light M1, M2... Image

Claims

1. A fusion splicer for fusion-splicing a first multi-core fiber having a plurality of first cores exposed on a first end face and a second multi-core fiber having a plurality of second cores exposed on a second end face to each other, the fusion splicer comprising: a rotation mechanism for rotating the first multi-core fiber and the second multi-core fiber that are fusion-spliced to each other; a first microscope for observing the first multi-core fiber and the second multi-core fiber by receiving light emitted from a first light source along a first direction and incident on the first multi-core fiber and the second multi-core fiber; a second microscope for observing the first multi-core fiber and the second multi-core fiber by receiving light emitted from a second light source along a second direction intersecting the first direction and incident on the first multi-core fiber and the second multi-core fiber; and a calculation unit for calculating an estimated loss from an image of the first multi-core fiber and the second multi-core fiber acquired by the first microscope and an image of the first multi-core fiber and the second multi-core fiber acquired by the second microscope.

2. The fusion splicer according to claim 1, wherein the rotation mechanism rotates the first multi-core fiber and the second multi-core fiber until at least one of the first microscope and the second microscope can observe the plurality of first cores and the plurality of second cores.

3. The fusion splicer according to claim 1, wherein the rotation mechanism rotates the first multi-core fiber and the second multi-core fiber until both the first microscope and the second microscope can observe one of the first cores and one of the second cores.

4. The fusion splicer according to claim 1 or 2, wherein the first microscope acquires an image of the first multi-core fiber or the second multi-core fiber in a state where the focus position is shifted from a plane perpendicular to the optical axis of the first microscope and including the central axis of the first multi-core fiber or the second multi-core fiber, or the second microscope acquires an image of the first multi-core fiber or the second multi-core fiber in a state where the focus position is shifted from a plane perpendicular to the optical axis of the second microscope and including the central axis of the first multi-core fiber or the second multi-core fiber.

5. The calculation unit calculates the estimated loss from the amount of axial displacement, which is the amount of displacement of the axis of the second core with respect to the axis of the first core, the amount of angular displacement, which is the amount of displacement of the extending direction of the second core on the second end face with respect to the extending direction of the first core on the first end face, the mode field diameter of the first core, and the mode field diameter of the second core. The fusion splicing machine according to claim 1 or claim 2.

6. A fusion splicing method for fusion splicing a first multi-core fiber having a plurality of first cores exposed on a first end face to a second multi-core fiber having a plurality of second cores exposed on a second end face, the method comprising: rotating the first multi-core fiber and the second multi-core fiber that are fusion spliced to each other; observing the first multi-core fiber and the second multi-core fiber with a first microscope by receiving light emitted to the first multi-core fiber and the second multi-core fiber along a first direction; observing the first multi-core fiber and the second multi-core fiber with a second microscope by receiving light emitted to the first multi-core fiber and the second multi-core fiber along a second direction intersecting the first direction; and calculating an estimated loss from the images of the first multi-core fiber and the second multi-core fiber obtained by the first microscope and the images of the first multi-core fiber and the second multi-core fiber obtained by the second microscope. The fusion splicing method comprises the steps of:

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