Fusion splicing device and fusion splicing method

Abstract

A fusion splicing device (1A) comprises a first retention part (11), a second retention part (12), a light source (30), a light detection part (40), and a heating part (2). The first retention part (11) makes it possible, while retaining a first optical fiber (F1), to change the rotational angle of an end surface (F1a) of the first optical fiber around a center axis. The second retention part (12) makes it possible, while retaining a second optical fiber (F2), to change the rotational angle of an end surface (F2a) of the second optical fiber around a center axis. The light source (30) is configured so as to be able to change the center wavelength of a light while shining the light on a resin sheath (RS) of the first optical fiber (F1). The light detection part (40) detects the intensity of light that leaks through a resin sheath (RS) of the second optical fiber (F2) while the end surfaces of the first optical fiber (F1) and the second optical fiber (F2) are adjacent to one another. The heating part (40) fuses the end surfaces of the first optical fiber (F1) and the second optical fiber (F2) while the same are adjacent to one another.

Description

Fusion splicing device and fusion splicing method

[0001] This application claims priority to Japanese Application No. 2022-090670, filed on June 3, 2022, and incorporates by reference the entire contents of said Japanese application.

[0002] Patent Literature 1 discloses a method for connecting multi-core optical fibers. In this connection method, the connecting end faces of the first and second multi-core optical fibers are opposed to each other so that the axes of the first and second multi-core optical fibers are aligned. Test light is incident from the side of the first multi-core optical fiber and propagates through the cladding. Based on the test light detected from the second multi-core optical fiber, axial rotation adjustment of the first and second multi-core optical fibers is performed.

[0003] Patent Document 2 discloses a method for splicing a first optical fiber and a second optical fiber that is a multi-core optical fiber. This method includes a facing step, a bending step, an input step, a measurement step, an alignment step, and a splicing step. In the facing step, the central axes of the two optical fibers are parallel and the end faces of the two optical fibers are brought face to face. In the bending step, a portion of the second optical fiber is bent. In the input step, light is input into the core from one end of the first optical fiber, and the light output from the other end is input into the second optical fiber. In the measurement step, the intensity of light emitted from the bent portion of the second optical fiber is measured. In the aligning step, at least one of the two optical fibers is moved or rotated while maintaining the parallelism of the central axes of both optical fibers to increase the light intensity. In the splicing step, the distance between the two optical fibers is changed while maintaining the positional relationship between the two optical fibers at which the light intensity is maximized, and the end portions are spliced ​​together.

[0004] Patent Document 3 discloses a method for fusion splicing the end faces of a pair of optical fibers. In this method, an image of the end face of the optical fiber is captured from the front using an imaging device arranged opposite the end face of the optical fiber. Any chips detected by the detection device are discharged by a discharging device to the end face of the optical fiber having a hackle. The end faces of the optical fibers are then fusion spliced ​​together.

[0005] JP 2017-21190 A JP 2015-4762 A International Publication No. 2013-77002

[0006] Examples of optical fibers that require adjustment of the rotation angle around the central axis during fusion splicing include multi-core optical fibers and polarization-maintaining fibers. When fusion splicing optical fibers that require adjustment of the rotation angle, for example, one of the following methods can be used. In one method, light is incident on the side of one optical fiber, and the intensity of the light leaking from the side of the other optical fiber is detected. The relative rotation angle between the optical fibers is then adjusted based on the detected intensity. In another method, light is incident on the side of each optical fiber while observing the end face of each optical fiber, and the rotation angle of each optical fiber is adjusted individually. When fusion splicing optical fibers, the coating resin is removed from the tip portion of the optical fiber, including the end face to be spliced, to expose the glass portion including the core and cladding. Configurations for introducing light from the side of the optical fiber include a configuration in which light is incident on the side of the glass portion exposed from the resin coating, and a configuration in which light is incident on the side of the resin coating. One of these configurations is appropriately selected in the fusion splicing device.

[0007] When light is incident on the side of the resin coating, the following problem occurs. Typically, a coloring material (e.g., a pigment) is mixed into the resin coating to identify the type of optical fiber. Alternatively, light-diffusing particles are mixed into the resin coating to improve the appearance of the optical fiber. These coloring materials and particles absorb or scatter the light incident on the resin coating, preventing the light from passing through the resin coating and reaching the glass portion. Therefore, it may be impossible to obtain the intensity of the light leaking from the side of the other optical fiber or the brightness of the observed image of the end face of the optical fiber, which is sufficient for adjusting the rotation angle. In such cases, adjusting the rotation angle becomes difficult.

[0008] An object of the present disclosure is to provide a fusion splicing device and a fusion splicing method that, when light is incident on the side of a resin coating to adjust the relative rotation angle between optical fibers, makes it easier for light incident on the resin coating to pass through the resin coating and reach the glass portion.

[0009] A fusion splicing device according to one aspect of the present disclosure includes a first holding unit, a second holding unit, a light source, a light detector, and a heating unit. The first holding unit, while holding a first optical fiber, varies the rotation angle of an end face of the first optical fiber about a central axis. The first optical fiber has a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion. In the first optical fiber, a tip portion of the glass portion, including the end face, is exposed from the resin coating. The second holding unit, while holding a second optical fiber, varies the rotation angle of the end face of the second optical fiber about a central axis. The second optical fiber has a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion. In the second optical fiber, a tip portion of the glass portion, including the end face, is exposed from the resin coating. The light source irradiates light onto the resin coating of the first optical fiber and is configured to have one or both of the following characteristics: the center wavelength of the light is tunable, and the wavelength bandwidth of the light is 100 nm or more. The light detection unit detects the intensity of light leaking through the resin coating of the second optical fiber while the end faces of the first optical fiber and the second optical fiber are close to each other. The heating unit heats the end faces of the first optical fiber and the second optical fiber to melt them while they are close to each other.

[0010] A fusion splicing method according to an embodiment of the present disclosure includes the steps of: preparing a first optical fiber and a second optical fiber, each having a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion, wherein a tip portion of the glass portion including an end face is exposed from the resin coating; bringing the end face of the first optical fiber and the end face of the second optical fiber closer to each other; irradiating light onto the resin coating of the first optical fiber using a light source configured to have one or both of the following characteristics: the center wavelength of the output light is tunable; and the wavelength bandwidth of the output light is 100 nm or more; detecting the intensity of light leaking through the resin coating of the second optical fiber; adjusting the relative rotation angle between the first optical fiber and the second optical fiber based on the intensity of the light detected in the detecting step; and heating and melting the end faces of the first optical fiber and the second optical fiber.

[0011] According to the present disclosure, a fusion splicing device and a fusion splicing method can be provided that, when light is incident on the side of the resin coating to adjust the relative rotation angle between optical fibers, makes it easier for the light incident on the resin coating to pass through the resin coating and reach the glass portion.

[0012] FIG. 1 is a diagram for explaining an overview of a fusion splicing device according to a first embodiment. FIG. 2 is a side view of a first optical fiber and a second optical fiber. FIG. 3 is a cross-sectional view of the first optical fiber and the second optical fiber taken along the III-III cross section shown in FIG. 2. FIG. 4 is a diagram schematically showing a cross section of a first holding unit and a second holding unit along the YZ plane. FIG. 5 is a diagram schematically showing an example configuration of a light source. FIG. 6 is a diagram schematically showing another example configuration of a light source. FIG. 7 is a flowchart showing the operation of the fusion splicing device according to the first embodiment. FIG. 8 is a diagram showing part of the configuration of a fusion splicing device according to a second embodiment. FIG. 9 is a flowchart showing the operation of the fusion splicing device according to the second embodiment.

[0013] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0014] [1] A fusion splicing device according to a first aspect of the present disclosure includes a first holding unit, a second holding unit, a light source, a light detector, and a heating unit. The first holding unit, while holding a first optical fiber, varies the rotation angle of an end face of the first optical fiber about a central axis. The first optical fiber has a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion. In the first optical fiber, a tip portion of the glass portion, including the end face, is exposed from the resin coating. The second holding unit, while holding a second optical fiber, varies the rotation angle of the end face of the second optical fiber about a central axis. The second optical fiber has a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion. In the second optical fiber, a tip portion of the glass portion, including the end face, is exposed from the resin coating. The light source irradiates light onto the resin coating of the first optical fiber. The light source is configured to have one or both of the following characteristics: a tunable center wavelength of light; and a wavelength bandwidth of light of 100 nm or more. The light detection unit detects the intensity of light leaking through the resin coating of the second optical fiber when the end faces of the first optical fiber and the second optical fiber are close to each other. The heating unit heats the end faces of the first optical fiber and the second optical fiber to melt them when they are close to each other.

[0015] In this fusion splicing device, the light source that irradiates the resin coating of the first optical fiber with light is configured to have one or both of the following characteristics: a tunable center wavelength of light; and a wavelength bandwidth of light of 100 nm or more. As described above, the coloring material and particles contained in the resin coating absorb or scatter light incident on the resin coating, with the magnitude of absorption and scattering depending on the wavelength of the light. With this fusion splicing device, by selecting a wavelength that is less absorbed and scattered by the resin coating and irradiating the resin coating with light of that wavelength, the light more easily passes through the resin coating and reaches the glass portion. This increases the intensity of light that leaks through the resin coating of the second optical fiber, allowing for optimal adjustment of the rotation angle. Alternatively, by configuring the light source to have a wavelength bandwidth of light of 100 nm or more, such broadband light can be used to adjust the rotation angles of multiple types of optical fibers with different resin coating absorption and scattering characteristics using light of the same wavelength. This reduces the frequency with which the wavelength of light needs to be changed, thereby reducing the operator's workload. In addition, by using broadband light having a bandwidth of 100 nm or more, at least one wavelength component within that bandwidth, typically the wavelength component with the least absorption and scattering within that bandwidth, can easily pass through the resin coating and reach the glass portion, thereby increasing the intensity of the light leaking through the resin coating of the second optical fiber and enabling the rotation angle to be adjusted appropriately.

[0016] [2] In the fusion splicing device of [1] above, the light detection unit may be configured so that the center wavelength of the band to which it has sensitivity is variable. In this case, light can be detected with optimal sensitivity according to the wavelength of the light, and the light detection efficiency can be improved, allowing for more accurate adjustment of the rotation angle.

[0017] [3] A fusion splicing device according to a second aspect of the present disclosure includes a first holding unit, a second holding unit, a first light source, a second light source, an imaging unit, and a heating unit. The first holding unit, while holding a first optical fiber, varies the rotation angle of an end face of the first optical fiber about a central axis. The first optical fiber has a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion. In the first optical fiber, a tip portion of the glass portion, including the end face, is exposed from the resin coating. The second holding unit, while holding a second optical fiber, varies the rotation angle of the end face of the second optical fiber about a central axis. The second optical fiber has a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion. In the second optical fiber, a tip portion of the glass portion, including the end face, is exposed from the resin coating. The first light source irradiates the resin coating of the first optical fiber with first light. The first light source is configured to have one or both of the following characteristics: a tunable central wavelength of the first light and a wavelength bandwidth of the first light of 100 nm or more. The second light source irradiates the resin coating of the second optical fiber with the second light. The second light source is configured to have one or both of the following characteristics: a tunable central wavelength of the second light and a wavelength bandwidth of the second light of 100 nm or more. The imaging unit acquires observation images of the end faces of the first optical fiber and the second optical fiber, respectively. The heating unit heats the end faces of the first optical fiber and the second optical fiber to melt the end faces of the first optical fiber and the second optical fiber while they are close to each other.

[0018] In this fusion splicing device, the first light source that irradiates the resin coating of the first optical fiber with light is configured to have one or both of the following characteristics: the center wavelength of the first light is tunable, and the wavelength bandwidth of the first light is 100 nm or more. Additionally, the second light source that irradiates the resin coating of the second optical fiber with light is configured to have one or both of the following characteristics: the center wavelength of the second light is tunable, and the wavelength bandwidth of the second light is 100 nm or more. As described above, the coloring material and particles contained in the resin coating absorb or scatter light incident on the resin coating, and the degree of absorption and scattering depends on the wavelength of the light. With this fusion splicing device, wavelengths that are least absorbed and scattered by the resin coating are selected, and first and second light of those wavelengths are irradiated onto the resin coatings of the first and second optical fibers, respectively. This makes it easier for the first and second light to pass through the resin coating and reach the glass portion. This allows for a brighter observation image of the end faces of the first and second optical fibers, and allows for convenient adjustment of the rotation angle. Alternatively, by configuring the first light source and the second light source so that the wavelength bandwidth of each of the first light and the second light is 100 nm or more, such broadband light can be used to adjust the rotation angles of multiple types of optical fibers having different resin coating absorption and scattering characteristics using light of the same wavelength. This reduces the frequency with which the wavelengths of the first light source and the second light source are changed, thereby reducing the amount of work required by the operator. Additionally, by using broadband first light and second light with a bandwidth of 100 nm or more, at least one wavelength component within that band, typically the wavelength component with the smallest absorption and scattering within that band, can easily pass through the resin coating and reach the glass portion. This allows the observed image of the end face of the first optical fiber and the second optical fiber to be brighter, making it possible to conveniently adjust the rotation angle.

[0019] [4] In the fusion splicing device of [3] above, the image capturing unit may be configured so that the center wavelength of the band to which it has sensitivity is variable. In this case, the first light and the second light can be captured with optimal sensitivity according to the wavelengths of the first light and the second light, and the observed images of the end faces of the first optical fiber and the second optical fiber can be brighter, allowing for more accurate adjustment of the rotation angle.

[0020] [5] In the fusion splicing device of [1] or [2] above, the light source may be configured to vary the intensity of light irradiated onto the resin coating of the first optical fiber. In this case, the intensity of light can be easily adjusted, for example, by lowering the intensity of light when the intensity of light incident on the light detection unit exceeds the maximum light amount allowed by the light detection unit, or by increasing the intensity of light when the intensity of light incident on the light detection unit is too low. Therefore, the rotation angle can be suitably adjusted by appropriately adjusting the intensity of light leaking through the resin coating of the second optical fiber.

[0021] [6] In the fusion splicing device of [3] or [4] above, the first light source may be configured to vary the intensity of the first light irradiated onto the resin coating of the first optical fiber, and the second light source may be configured to vary the intensity of the second light irradiated onto the resin coating of the second optical fiber. In this case, the intensities of the first and second lights can be easily adjusted, for example, by lowering the intensities of the first and second lights when the intensities of the first and second lights incident on the imaging unit exceed the maximum light amount allowed by the imaging unit, or by increasing the intensities of the first and second lights when the intensities of the first and second lights incident on the imaging unit are too low. Therefore, by appropriately adjusting the intensities of the first and second lights emitted from the end faces of the first and second optical fibers, it is possible to appropriately obtain observation images of the end faces of the first and second optical fibers and to suitably adjust the rotation angle.

[0022] [7] A fusion splicing method according to a first aspect of the present disclosure includes the steps of: preparing a first optical fiber and a second optical fiber, each having a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion, wherein a tip portion of the glass portion including an end face is exposed from the resin coating; bringing the end face of the first optical fiber and the end face of the second optical fiber closer to each other; irradiating the resin coating of the first optical fiber with light using a light source configured to have one or both of the following characteristics: the center wavelength of the output light is tunable; and a wavelength bandwidth of the output light is 100 nm or more; detecting the intensity of light leaking through the resin coating of the second optical fiber; adjusting the relative rotation angle between the first optical fiber and the second optical fiber based on the intensity of the light detected in the detecting step; and heating and melting the end faces of the first optical fiber and the second optical fiber.

[0023] In this fusion splicing method, a light source configured to have one or both of the following characteristics is used to irradiate the resin coating of the first optical fiber: the center wavelength of the output light is tunable; and the wavelength bandwidth of the output light is 100 nm or more. This fusion splicing method increases the intensity of the light leaking through the resin coating of the second optical fiber, thereby enabling favorable adjustment of the rotation angle, for the same reasons as in the fusion splicing device described above in [1].

[0024] [8] In the fusion splicing apparatus of [7] above, the detecting step may detect the light intensity using a photodetector configured so that the center wavelength of the sensitive band is variable. In this case, light can be detected with optimal sensitivity according to the wavelength of the light, and the light detection efficiency can be improved, allowing for more accurate adjustment of the rotation angle.

[0025] [9] A fusion splicing method according to a second aspect of the present disclosure includes the steps of preparing a first optical fiber and a second optical fiber, each having a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion, wherein a tip portion of the glass portion including an end face is exposed from the resin coating; and acquiring an observation image of the end face of the first optical fiber while irradiating the resin coating of the first optical fiber with first light using a first light source configured to have one or both of the following characteristics: the center wavelength of the output light is tunable; and the wavelength bandwidth of the output light is 100 nm or more. the step of obtaining an observation image of the end face of the second optical fiber while irradiating the resin coating of the second optical fiber with second light using a second light source configured to have one or both of the characteristics of a tunable center wavelength of the output light and a wavelength bandwidth of the output light being 100 nm or more; the step of adjusting the relative rotation angle between the first optical fiber and the second optical fiber based on the observation image of the end face of the first optical fiber and the observation image of the end face of the second optical fiber; the step of bringing the end face of the first optical fiber and the end face of the second optical fiber closer to each other; and the step of heating and melting the end faces of the first optical fiber and the second optical fiber.

[0026] In this fusion splicing method, a first light source and a second light source are used that are configured to have one or both of the following characteristics: the center wavelength of the output light is tunable; and the wavelength bandwidth of the output light is 100 nm or more. The resin coatings of the first optical fiber and the second optical fiber are irradiated with the first light and the second light, respectively. For the same reasons as in the fusion splicing device described in [3] above, this fusion splicing method makes it possible to brighten the observed images of the end faces of the first optical fiber and the second optical fiber, thereby enabling favorable adjustment of the rotation angle.

[0027]

[10] In the fusion splicing method of [9] above, in each of the steps of acquiring an observation image of the end face of the first optical fiber and acquiring an observation image of the end face of the second optical fiber, the observation images of the end face of the first optical fiber and the observation images of the end face of the second optical fiber may be acquired using an imaging device configured to have a variable center wavelength of a band of sensitivity. In this case, the first light and the second light can be detected with optimal sensitivity according to the wavelengths of the first light and the second light, and the detection efficiency of the first light and the second light can be improved, allowing for more accurate adjustment of the rotation angle.

[0028]

[11] In the fusion splicing method according to [7] or [8], the irradiating step may be performed using a light source configured to vary the intensity of the light irradiated onto the resin coating of the first optical fiber. In this case, the intensity of the light can be easily adjusted, for example, by lowering the intensity of the light when the intensity of the light incident on the light detection unit exceeds the maximum light amount allowed by the light detection unit, or by increasing the intensity of the light when the intensity of the light incident on the light detection unit is too low. Therefore, the rotation angle can be suitably adjusted by appropriately adjusting the intensity of the light leaking through the resin coating of the second optical fiber.

[0029]

[12] In the fusion splicing method according to [9] or

[10] above, in the step of acquiring an observation image of the end face of the first optical fiber, the first light may be emitted using a first light source configured to vary the intensity of the first light, and in the step of acquiring an observation image of the end face of the second optical fiber, the second light may be emitted using a second light source configured to vary the intensity of the second light. In this case, the intensities of the first and second lights can be easily adjusted, for example, by lowering the intensities of the first and second lights when the intensities of the first and second lights incident on the image capture unit exceed the maximum light amount allowed by the image capture unit, or by increasing the intensities of the first and second lights when the intensities of the first and second lights incident on the image capture unit are too low. Therefore, by appropriately adjusting the intensities of the first and second lights emitted from the end faces of the first and second optical fibers, the observation images of the end faces of the first and second optical fibers can be appropriately acquired, and the rotation angle can be suitably adjusted. [Details of the Embodiments of the Present Disclosure]

[0030] Specific examples of embodiments of the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the following description, the same elements in the description of the drawings will be given the same reference numerals, and duplicate explanations will be omitted. (First embodiment)

[0031] FIG. 1 is a diagram illustrating an overview of a fusion splicing apparatus 1A according to a first embodiment. An XYZ Cartesian coordinate system is also shown in FIG. 1. As shown in FIG. 1, the fusion splicing apparatus 1A is an apparatus that fusion-splices an end face F1a of a first optical fiber F1 and an end face F2a of a second optical fiber F2 to each other. FIG. 2 is a side view of the first optical fiber F1 and the second optical fiber F2. FIG. 3 is a cross-sectional view of the first optical fiber F1 and the second optical fiber F2 taken along the III-III cross section shown in FIG. 2. As shown in FIG. 3, the first optical fiber F1 and the second optical fiber F2 each have a glass portion GL and a resin coating RS surrounding the outer periphery of the glass portion GL. The glass portion GL has one or more (four in the illustrated example) cores CR, one marker MK, and a common cladding CL surrounding the cores CR and the marker MK. The refractive index of the cores CR is greater than the refractive index of the common cladding CL. The marker MK may be transparent or opaque. 3 shows a multi-core optical fiber (MCF) having multiple cores CR as the first optical fiber F1 and the second optical fiber F2. The first optical fiber F1 and the second optical fiber F2 may be any optical fiber that requires rotational alignment during fusion splicing, and are not limited to multi-core optical fibers. The first optical fiber F1 and the second optical fiber F2 may also be an optical fiber having a single core, for example, a polarization-maintaining fiber (PMF).

[0032] 2, in the first optical fiber F1, a tip portion GL1 of the glass portion GL, including an end face F1a, is exposed from the resin coating RS. In the second optical fiber F2, a tip portion GL2 of the glass portion GL, including an end face F2a, is exposed from the resin coating RS. These exposed portions are formed by removing the resin coating RS around the tip portions GL1 and GL2 before the fusion splicing operation.

[0033] Referring again to FIG. 1 , the fusion splicing apparatus 1A includes a first holding unit 11 and a second holding unit 12. The first holding unit 11, while holding the first optical fiber F1, varies the spatial position of the end face F1a of the first optical fiber F1 and the rotation angle θ about the central axis. The spatial position refers to the position in each of the X-axis, Y-axis, and Z-axis. The second holding unit 12, while holding the second optical fiber F2, varies the spatial position of the end face F2a of the second optical fiber F2 and the rotation angle θ about the central axis. The first holding unit 11 and the second holding unit 12 are aligned along the Z-axis direction, which is the direction of the central axes of the first optical fiber F1 and the second optical fiber F2. The first holding unit 11 has a V-groove 111 extending along the Z-axis direction. The V-groove 111 accommodates a portion of the first optical fiber F1 excluding the tip portion GL1, i.e., the portion of the first optical fiber F1 having the resin coating RS, and fixes the position of the first optical fiber F1 in the XY plane. The first holding unit 11 holds the first optical fiber F1 with the tip portion GL1 protruding. The second holding unit 12 has a V-groove 121 extending along the Z-axis direction. The V-groove 121 accommodates the portion of the second optical fiber F2 excluding the tip portion GL2, i.e., the portion of the second optical fiber F2 having the resin coating RS, and fixes the position of the second optical fiber F2 in the XY plane. The second holding unit 12 holds the second optical fiber F2 with the tip portion GL2 protruding.

[0034] In one embodiment, the first holding unit 11 and the second holding unit 12 are made of resin. The first holding unit 11 has, for example, a base 112 having a V-groove 111 formed therein and on which the first optical fiber F1 is placed, and a lid 113 placed on the base 112. The base 112 and the lid 113 are arranged, for example, to be aligned along the Y-axis direction intersecting the Z-axis direction. The second holding unit 12 has, for example, a base 122 having a V-groove 121 formed therein and on which the second optical fiber F2 is placed, and a lid 123 placed on the base 122. The base 122 and the lid 123 are arranged, for example, to be aligned along the Y-axis direction.

[0035] The fusion splicing apparatus 1A further includes a first driver 21 and a second driver 22. The first driver 21 supports the first holder 11 and controls the spatial position of the first holder 11 and the rotation angle θ of the first holder 11 about the Z axis. The first driver 21 controls the spatial position and rotation angle θ of the first holder 11, thereby controlling the spatial position and rotation angle θ of the end face F1a of the first optical fiber F1. The second driver 22 supports the second holder 12 and controls the spatial position of the second holder 12 and the rotation angle θ of the second holder 12 about the Z axis. The second driver 22 controls the spatial position and rotation angle θ of the second holder 12, thereby controlling the spatial position and rotation angle θ of the end face F2a of the second optical fiber F2. The first driver 21 and the second driver 22 each include, for example, a motor.

[0036] The fusion splicing apparatus 1A further includes a pair of discharge electrodes 2. The pair of discharge electrodes 2 are disposed at positions where the end face F1 a of the first optical fiber F1 and the end face F2 a of the second optical fiber F2 face each other. The pair of discharge electrodes 2 are disposed to face each other along the X-axis direction, which intersects both the Z-axis direction and the Y-axis direction. The pair of discharge electrodes 2 are heating units that heat the end face F1 a of the first optical fiber F1 and the end face F2 a of the second optical fiber F2 by electric discharge in order to melt the end face F1 a of the first optical fiber F1 and the end face F2 a of the second optical fiber F2 while they are in close proximity to each other.

[0037] The fusion splicing apparatus 1A further includes a control unit 3A. The control unit 3A may be configured, for example, by a computer including a CPU and a memory. The control unit 3A is electrically connected to a power source that supplies power to the discharge electrode 2 and controls the discharge current and discharge time of the discharge electrode 2. This allows fusion splicing to be performed under conditions suitable for the types of the first optical fiber F1 and the second optical fiber F2. In addition, the control unit 3A controls the operations of the first drive unit 21 and the second drive unit 22. The operations of the first drive unit 21 and the second drive unit 22 include the following three operations. One is an operation for bringing the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2 closer to each other. Another is an operation for adjusting the relative positions of the end faces F1a and F2a in the XY plane (i.e., axial alignment). Yet another is an operation for adjusting the relative rotation angle θ between the end faces F1a and F2a.

[0038] The control unit 3A axially aligns the first optical fiber F1 and the second optical fiber F2 as follows: First, an image of the vicinity of the end faces F1 a, F2 a of the first optical fiber F1 and the second optical fiber F2 is captured using a camera positioned laterally (in two directions intersecting the Z-axis direction and perpendicular to each other) relative to the end faces F1 a and F2 a. The control unit 3A then controls the first drive unit 21 and the second drive unit 22 so that the central axes of the first optical fiber F1 and the second optical fiber F2 included in the captured image are aligned with each other.

[0039] FIG. 4 is a schematic diagram showing a cross section of the first holding unit 11 and the second holding unit 12 taken along the YZ plane. As shown in FIG. 4 , the fusion splicing device 1A further includes a light source 30 and a light detection unit 40. The light source 30 irradiates light L onto the resin coating RS of the first optical fiber F1. In one example, the light source 30 is provided inside the first holding unit 11 so as to be in contact with the first optical fiber F1. The light source 30 may also be provided so as to press against the resin coating RS of the first optical fiber F1. The location of the light source 30 is not limited thereto, and the light source 30 may also be provided outside the first holding unit 11. The light source 30 may also be provided away from the first optical fiber F1. In this case, the light source 30 may emit light L into a curved portion formed by bending the first optical fiber F1.

[0040] The light detecting unit 40 is a power meter that detects the intensity of light L that passes through the resin coating RS of the second optical fiber F2 and leaks when the end face F1 a of the first optical fiber F1 and the end face F2 a of the second optical fiber F2 are in close proximity to each other. In one example, the light detecting unit 40 is provided inside the second holding unit 12 so as to be in contact with the second optical fiber F2. The location of the light detecting unit 40 is not limited to this, and the light detecting unit 40 may be provided outside the second holding unit 12. The light detecting unit 40 may be provided away from the second optical fiber F2. In this case, the light detecting unit 40 may detect light L that leaks from a curved portion formed by bending the second optical fiber F2.

[0041] The light source 30 and the light detection unit 40 are electrically connected to the control unit 3A shown in FIG. 1 . The control unit 3A controls the output operation of the light source 30 to output the light L. In addition, the control unit 3A receives a signal from the light detection unit 40 indicating the intensity of the light L detected by the light detection unit 40. The light L irradiated onto the resin coating RS of the first optical fiber F1 passes through the resin coating RS of the first optical fiber F1, enters the glass portion GL, and is collected at each core CR. The light L then propagates through each core CR of the first optical fiber F1 and then propagates through each core CR of the second optical fiber F2. Leaked light of the light L leaks through the resin coating RS of the second optical fiber F2. It is this leaked light L that is detected by the light detection unit 40. FIG. 4 illustrates only one core CR among the multiple cores CR.

[0042] When the position of the core CR of the first optical fiber F1 and the position of the core CR of the second optical fiber F2 are misaligned from each other, the greater the amount of misalignment, the more difficult it becomes for light L to propagate from the core CR of the first optical fiber F1 to the core CR of the second optical fiber F2. As a result, the light intensity detected by the light detection unit 40 decreases. Therefore, the control unit 3A controls one or both of the first driving unit 21 and the second driving unit 22 to adjust the relative rotation angle θ between the end face F1a and the end face F2a so that the light intensity detected by the light detection unit 40 approaches its maximum value. This makes it possible to align the position of the core CR of the first optical fiber F1 and the position of the core CR of the second optical fiber F2 with each other.

[0043] The light source 30 is configured so that the center wavelength of the light L is variable. FIGS. 5 and 6 are schematic diagrams illustrating light sources 30A and 30B, respectively, as configuration examples of the light source 30. The light source 30A shown in FIG. 5 includes a plurality of light-emitting elements 31. The center wavelengths of the emission wavelength bands of the plurality of light-emitting elements 31 are different from one another. The emission wavelength bands of the plurality of light-emitting elements 31 may or may not overlap. The center wavelength of the light L is selected by selectively supplying current to one of the plurality of light-emitting elements 31. The emission wavelength bandwidth of each light-emitting element 31 may be a wide band, such as 100 nm or more, or may be a narrow band less than 100 nm. The emission wavelength bands of the plurality of light-emitting elements 31 may be set to divide a wavelength band of, for example, 400 nm to 2000 nm.

[0044] The light source 30B shown in Fig. 6 has a light-emitting element 32 and a tunable wavelength filter 33. The light-emitting element 32 is an element that outputs broad light in a wide band (for example, 400 nm to 2000 nm). The tunable wavelength filter 33 is a band-pass filter that receives light from the light-emitting element 32 and passes only a portion of the wavelength band components of the light. The tunable wavelength filter 33 is configured to be able to change the passing wavelength band. By changing the passing wavelength band of the tunable wavelength filter 33, the center wavelength of the light passing through the tunable wavelength filter 33, i.e., the light L output from the light source 30B, is changed.

[0045] In the light source 30, the central wavelength of the light L may be fixed rather than variable. In this case, the light source 30 is configured so that the bandwidth of the wavelength of the light L is 100 nm or more, for example, 1000 nm or more. In one example, the light source 30 outputs broad light having a wavelength band of, for example, 400 nm to 2000 nm. In this case, the bandwidth of the wavelength of the light L is 1600 nm.

[0046] The light detection unit 40 may be configured so that the center wavelength of the wavelength band to which it is sensitive is variable. In this case, the wavelength band to which the light detection unit 40 is sensitive may be set to match the wavelength band of the light L output from the light source 30. In one example, the center wavelength of the wavelength band to which the light detection unit 40 is sensitive is set to match the center wavelength of the wavelength band of the light L output from the light source 30.

[0047] FIG. 7 is a flowchart showing the operation of the fusion splicing apparatus 1A. The operation of the fusion splicing apparatus 1A and the fusion splicing method according to this embodiment will be described with reference to FIG. First, in step ST11, the control unit 3A controls the first driver 21 and the second driver 22 so that the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2 approach each other. This causes the end faces F1a and F2a to face each other. However, there is a slight gap between the end faces F1a and F2a. Next, in step ST12, the axes of the first optical fiber F1 and the second optical fiber F2 are aligned. Specifically, cameras positioned to the sides of the end faces F1a and F2a are used to capture images of the vicinity of the end faces F1a and F2a of the first optical fiber F1 and the second optical fiber F2. The control unit 3A then controls the first driver 21 and the second driver 22 so that the central axes of the first optical fiber F1 and the second optical fiber F2 included in the observed images coincide with each other.

[0048] In the subsequent step ST13, the light source 30, whose center wavelength of output light is tunable, irradiates the resin coating RS of the first optical fiber F1 with light L. Alternatively, in step ST13, the light source 30, whose center wavelength of output light is fixed, may irradiate the resin coating RS of the first optical fiber F1 with light L having a wavelength bandwidth of 100 nm or more. Then, in step ST14, the light detection unit 40 detects the intensity of the light L that passes through the resin coating RS of the second optical fiber F2 and leaks. As described above, the light detection unit 40 may be configured so that the center wavelength of the wavelength band to which it is sensitive is tunable. Then, in step ST15, the control unit 3A adjusts the relative rotation angle θ between the first optical fiber F1 and the second optical fiber F2 based on the intensity of the light L detected in step ST14. At this time, the control unit 3A adjusts the relative rotation angle θ between the end face F1a and the end face F2a by controlling one or both of the first drive unit 21 and the second drive unit 22 so that the light intensity detected by the light detection unit 40 approaches a maximum value. Then, in step ST16, discharge is generated between a pair of discharge electrodes 2, and the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2 are heated and melted, thereby connecting the end face F1a and the end face F2a to each other.

[0049] The effects achieved by the fusion splicing device and fusion splicing method of this embodiment, which are configured as described above, are described below. In the fusion splicing device 1A of this embodiment, the light source 30 that irradiates light L onto the resin coating RS of the first optical fiber F1 is configured so that the center wavelength of the light L is tunable. In the fusion splicing method of this embodiment, the light source 30 with a tunable center wavelength of output light is also used to irradiate the resin coating RS of the first optical fiber F1 with light. As described above, the coloring material and particles contained in the resin coating RS absorb or scatter the light L incident on the resin coating RS, and the magnitude of this absorption and scattering depends on the wavelength of the light L. According to the fusion splicing device 1A and fusion splicing method of this embodiment, by selecting a wavelength that is less absorbed and scattered by the resin coating RS and irradiating the resin coating RS with light L of that wavelength, the light L is more likely to pass through the resin coating RS and reach the glass portion GL. In addition, light L is more likely to leak from the resin coating RS of the second optical fiber F2. Therefore, according to this embodiment, the intensity of the light L leaking through the resin coating RS of the second optical fiber F2 can be increased, and the rotation angle θ can be suitably adjusted. The wavelength of the light L may be changed automatically by the control unit 3A in accordance with the types of the first optical fiber F1 and the second optical fiber F2 input before fusion splicing. Alternatively, the wavelength of the light L may be changed by an operator via an input unit such as a switch provided in the fusion splicing device 1A.

[0050] As described above, the light source 30 may be configured so that the wavelength bandwidth of the light L is 100 nm or more. By using such a broadband light L, it is possible to adjust the rotation angle θ of multiple types of optical fibers having different absorption and scattering characteristics of the resin coating RS using light L of the same wavelength. This reduces the frequency with which the wavelength of the light L needs to be changed, thereby reducing the workload of the operator.

[0051] As described above, the light detection unit 40 may be configured so that the center wavelength of the band to which it is sensitive is variable. In this case, it is possible to detect the light L with optimal sensitivity according to the wavelength of the light L. This increases the detection efficiency of the light L and allows for more accurate adjustment of the rotation angle θ.

[0052] As described above, the light source 30 may be configured so that the center wavelength of the light L is fixed rather than variable, and the wavelength bandwidth of the light L is 100 nm or more. In step ST13 of the fusion splicing method of this embodiment, a light source 30 having a fixed rather than variable center wavelength of the light L may also be used to irradiate the resin coating RS of the first optical fiber F1 with light L having a wavelength bandwidth of 100 nm or more. As described above, the coloring material and particles contained in the resin coating RS absorb or scatter the light L incident on the resin coating RS, with the magnitude of absorption and scattering depending on the wavelength of the light L. By using broadband light L with a bandwidth of 100 nm or more, at least one wavelength component included in that bandwidth, typically the wavelength component included in that bandwidth with the smallest absorption and scattering, passes through the resin coating RS and easily reaches the glass portion GL. Therefore, the intensity of the light L leaking through the resin coating RS of the second optical fiber F2 can be increased, and the rotation angle θ can be suitably adjusted.

[0053] In this embodiment, the light source 30 may be configured to vary the intensity of the light L irradiated onto the resin coating RS of the first optical fiber F1. In this case, the intensity of the light L can be easily adjusted, for example, by lowering the intensity of the light L when the intensity of the light L incident on the light detection unit 40 exceeds the maximum light amount allowed by the light detection unit 40, or by increasing the intensity of the light L when the intensity of the light L incident on the light detection unit 40 is too low. Therefore, the rotation angle θ can be suitably adjusted by appropriately adjusting the intensity of the light L leaking through the resin coating RS of the second optical fiber F2. The intensity of the light L may be automatically changed by the control unit 3A based on the intensity of the light L incident on the light detection unit 40. Alternatively, the intensity of the light L may be changed by an operator via an input unit, such as a switch, provided in the fusion splicing device 1A. (Second Embodiment)

[0054] 8 is a diagram showing a portion of the configuration of a fusion splicing apparatus 1B according to a second embodiment, and schematically shows a cross section along the YZ plane of a first holding unit 11 and a second holding unit 12. The fusion splicing apparatus 1B of this embodiment is an apparatus that fusion-splices an end face F1a of a first optical fiber F1 and an end face F2a of a second optical fiber F2 to each other. Like the first embodiment, the fusion splicing apparatus 1B includes a first holding unit 11, a second holding unit 12, a first driving unit 21, a second driving unit 22, and a pair of discharge electrodes 2. As shown in FIG. 8, the fusion splicing apparatus 1B of this embodiment includes a first light source 51, a second light source 52, an imaging unit 60, a mirror 61, and a control unit 3B, instead of the light source 30, the light detection unit 40, and the control unit 3A of the first embodiment.

[0055] The control unit 3B may be configured, for example, by a computer including a CPU and a memory. The control unit 3B is electrically connected to a power source that supplies power to the discharge electrode 2. The control unit 3B controls the discharge current and discharge time of the discharge electrode 2. This allows fusion splicing to be performed under conditions suitable for the types of the first optical fiber F1 and the second optical fiber F2. The control unit 3B controls the operations of the first drive unit 21 and the second drive unit 22. The operations of the first drive unit 21 and the second drive unit 22 include the following three operations: One is an operation to bring the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2 closer together; Another is an operation to adjust the relative positions of the end faces F1a and F2a in the XY plane (i.e., axial alignment); and Still Another is an operation to adjust the relative rotation angle θ between the end faces F1a and F2a. The process of axial alignment of the first optical fiber F1 and the second optical fiber F2 performed by the control unit 3B is the same as that performed by the control unit 3A in the first embodiment.

[0056] The first light source 51 irradiates the resin coating RS of the first optical fiber F1 with the first light L1. The first light L1 irradiated onto the resin coating RS of the first optical fiber F1 becomes observation light emitted from the end face F1a of the first optical fiber F1. In one example, the first light source 51 is provided inside the first holding unit 11 so as to be in contact with the first optical fiber F1. The first light source 51 may be provided so as to press against the resin coating RS of the first optical fiber F1. The arrangement of the first light source 51 is not limited thereto, and the first light source 51 may be provided outside the first holding unit 11. The first light source 51 may be provided away from the first optical fiber F1. In this case, the first light source 51 may emit the first light L1 into a curved portion formed by bending the first optical fiber F1. The first light source 51 is configured so that the center wavelength of the first light L1 is tunable. In this case, the first light source 51 may be configured so that the wavelength bandwidth of the first light L1 is 100 nm or more. An example configuration of the first light source 51 may be the same as the example configuration of the light source 30 of the first embodiment (see FIGS. 5 and 6 ). Alternatively, in the first light source 51, the center wavelength of the first light L1 may be fixed rather than variable. In this case, the first light source 51 is configured so that the wavelength bandwidth of the first light L1 is 100 nm or more, for example, 1000 nm or more. In one example, the first light source 51 outputs broad light having a wavelength band of, for example, 400 nm to 2000 nm. In this case, the wavelength bandwidth of the first light L1 is 1600 nm.

[0057] The second light source 52 irradiates the resin coating RS of the second optical fiber F2 with the second light L2. The second light L2 irradiated onto the resin coating RS of the second optical fiber F2 becomes observation light emitted from the end face F2a of the second optical fiber F2. In one example, the second light source 52 is provided inside the second holding unit 12 so as to be in contact with the second optical fiber F2. The second light source 52 may be provided so as to press against the resin coating RS of the second optical fiber F2. The arrangement of the second light source 52 is not limited thereto, and the second light source 52 may be provided outside the second holding unit 12. The second light source 52 may be provided away from the second optical fiber F2. In this case, the second light source 52 may emit the second light L2 into a curved portion formed by bending the second optical fiber F2. The second light source 52 is configured so that the center wavelength of the second light L2 is tunable. In this case, the second light source 52 may be configured so that the wavelength bandwidth of the second light L2 is 100 nm or more. An example configuration of the second light source 52 may be the same as that of the light source 30 of the first embodiment. Alternatively, in the second light source 52, the center wavelength of the second light L2 may be fixed rather than variable. In this case, the second light source 52 is configured so that the wavelength bandwidth of the second light L2 is 100 nm or more, for example, 1000 nm or more. In one example, the second light source 52 outputs broad light having a wavelength band of, for example, 400 nm to 2000 nm. In this case, the wavelength bandwidth of the second light L2 is 1600 nm.

[0058] The imaging unit 60 is a camera that captures observation images of the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2. In the illustrated example, the imaging unit 60 is disposed laterally (in a direction along the XY plane in FIG. 1 ) relative to the end faces F1a and F2a. The mirror 61 is disposed between the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2. The angle of the mirror 61 is adjusted along the swing direction A1 between an angle when the imaging unit 60 captures an image of the end face F1a of the first optical fiber F1 and an angle when the imaging unit 60 observes the end face F2a of the second optical fiber F2. When the mirror 61 is disposed so as to reflect observation light from the end face F1a of the first optical fiber F1 toward the imaging unit 60, the imaging unit 60 outputs an observation image of the end face F1a of the first optical fiber F1. When the mirror 61 is positioned so as to reflect the observation light from the end face F2a of the second optical fiber F2 toward the imaging unit 60, the imaging unit 60 outputs an observation image of the end face F2a of the second optical fiber F2.

[0059] The first light source 51, the second light source 52, and the image capture unit 60 are electrically connected to the control unit 3B. The control unit 3B controls the output operation of the first light source 51 to output the first light L1 and the output operation of the second light source 52 to output the second light L2. In addition, the control unit 3B inputs from the image capture unit 60 the observation images of the end faces F1a and F2a acquired by the image capture unit 60. In these observation images, the multiple cores CR are brightly indicated by the first light L1 and the second light L2. The control unit 3B adjusts the relative rotation angle θ between the first optical fiber F1 and the second optical fiber F2 based on the observation images of the end face F1a and the end face F2a. In other words, based on the observation images of the end face F1a and the end face F2a, the control unit 3B adjusts the rotation angle θ of one or both of the first optical fiber F1 and the second optical fiber F2 so that the positions of the multiple cores CR of the first optical fiber F1 in the XY plane and the positions of the multiple cores CR of the second optical fiber F2 in the XY plane coincide with each other.

[0060] The image capturing unit 60 may be configured so that the center wavelength of the wavelength band to which it is sensitive is variable. In this case, the wavelength band to which it is sensitive may be set to match the wavelength bands of the first light L1 and the second light L2 output from the first light source 51 and the second light source 52, respectively. In one example, the center wavelength of the wavelength band to which it is sensitive is set to match the center wavelength of the wavelength bands of the first light L1 and the second light L2 output from the first light source 51 and the second light source 52, respectively.

[0061] FIG. 9 is a flowchart showing the operation of the fusion splicing apparatus 1B. The operation of the fusion splicing apparatus 1B and the fusion splicing method according to this embodiment will be described with reference to FIG. First, in step ST21, a first light source 51 having a tunable center wavelength of output light irradiates the resin coating RS of the first optical fiber F1 with first light L1. Alternatively, in step ST21, the first light source 51 having a fixed center wavelength of output light may irradiate the resin coating RS of the first optical fiber F1 with first light L1 having a wavelength bandwidth of 100 nm or more. Then, while the first light source 51 continues to irradiate the first light L1, the imaging unit 60 acquires an observation image of the end face F1a of the first optical fiber F1. Next, in step ST22, a second light source 52 having a tunable center wavelength of output light irradiates the resin coating RS of the second optical fiber F2 with second light L2. Alternatively, in step ST22, the second light source 52, whose center wavelength of output light is fixed, may irradiate the resin coating RS of the second optical fiber F2 with the second light L2 having a wavelength bandwidth of 100 nm or more. Then, while the second light source 52 continues to irradiate the resin coating RS of the second optical fiber F2 with the second light L2, the imaging unit 60 acquires an observation image of the end face F2 a of the second optical fiber F2.

[0062] In the following step ST23, the relative rotation angle between the first optical fiber F1 and the second optical fiber F2 is adjusted based on the observation image of the end face F1a of the first optical fiber F1 and the observation image of the end face F2a of the second optical fiber F2. Then, in step ST24, the control unit 3B controls the first drive unit 21 and the second drive unit 22 so that the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2 approach each other. As a result, the end faces F1a and F2a face each other. However, there is a slight gap between the end faces F1a and F2a. Next, in step ST25, the axes of the first optical fiber F1 and the second optical fiber F2 are aligned. Specifically, an image of the vicinity of the end faces F1a and F2a of the first optical fiber F1 and the second optical fiber F2 is captured using a camera positioned laterally relative to the end faces F1a and F2a. Then, the control unit 3B controls the first drive unit 21 and the second drive unit 22 so that the central axes of the first optical fiber F1 and the second optical fiber F2 included in the observation image coincide with each other. Then, in step ST26, discharge is generated between a pair of discharge electrodes 2, and the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2 are heated and melted, thereby connecting the end faces F1a and F2a to each other.

[0063] The effects obtained by the fusion splicing device and fusion splicing method of this embodiment having the above configuration will be described. In the fusion splicing device 1B of this embodiment, the first light source 51 that irradiates the resin coating RS of the first optical fiber F1 with a first light L1 and the second light source 52 that irradiates the resin coating RS of the second optical fiber F2 with a second light L2 are each configured so that the center wavelengths of the first light L1 and the second light L2 are tunable. In the fusion splicing method of this embodiment, the first light source 51 and the second light source 52 that have tunable center wavelengths of output light are also used to irradiate the resin coating RS of the first optical fiber F1 and the second optical fiber F2 with the first light L1 and the second light L2, respectively. As described above, the coloring material and particles contained in the resin coating RS absorb or scatter the first light L1 and the second light L2 incident on the resin coating RS, and the magnitude of absorption and scattering depends on the wavelengths of the first light L1 and the second light L2. According to the fusion splicing apparatus 1B and fusion splicing method of this embodiment, wavelengths that are minimally absorbed and scattered by the resin coating RS are selected, and the resin coating RS of the first optical fiber F1 and the second optical fiber F2 are irradiated with the first light L1 and the second light L2, respectively. This allows the first light L1 and the second light L2 to easily pass through the resin coating RS and reach the glass portion GL. Therefore, according to this embodiment, the observed images of the end face F1 a of the first optical fiber F1 and the end face F2 a of the second optical fiber F2 can be brightened, allowing for convenient adjustment of the rotation angle θ. The wavelengths of the first light L1 and the second light L2 may be automatically changed by the control unit 3B in accordance with the types of the first optical fiber F1 and the second optical fiber F2 input before fusion splicing. Alternatively, the wavelengths of the first light L1 and the second light L2 may be changed by an operator via an input unit, such as a switch, provided in the fusion splicing apparatus 1B.

[0064] As described above, the first light source 51 and the second light source 52 may be configured so that the wavelength bandwidths of the first light L1 and the second light L2 are 100 nm or greater. By using such broadband first light L1 and second light L2, the rotation angles θ of multiple types of optical fibers having different absorption and scattering characteristics of the resin coating RS can be adjusted using light of the same wavelength. This reduces the frequency with which the wavelengths of the first light L1 and the second light L2 need to be changed, thereby reducing the workload of the operator.

[0065] As described above, the image capturing unit 60 may be configured so that the center wavelength of the band to which it has sensitivity is variable. In this case, the first light L1 and the second light L2 can be captured with optimal sensitivity according to the wavelengths of the first light L1 and the second light L2, and the observed images of the end faces F1 a, F2 a of the first optical fiber F1 and the second optical fiber F2 can be brighter, allowing for more accurate adjustment of the rotation angle θ.

[0066] As described above, the first light source 51 and the second light source 52 may be configured so that the center wavelengths of the first light L1 and the second light L2 are fixed rather than variable, and the wavelength bandwidths of the first light L1 and the second light L2 are 100 nm or more. In steps ST21 and ST22 of the fusion splicing method of this embodiment, the first light source 51 and the second light source 52, each having a fixed rather than variable center wavelength, may be used to irradiate the resin coatings RS of the first optical fiber F1 and the second optical fiber F2 with first light L1 and second light L2 having wavelength bandwidths of 100 nm or more. As described above, the coloring material and particles contained in the resin coating RS absorb or scatter the first light L1 and second light L2 incident on the resin coating RS, and the magnitude of the absorption and scattering depends on the wavelengths of the first light L1 and second light L2. By using the first light L1 and the second light L2 having a broadband bandwidth of 100 nm or more, at least one wavelength component included in the bandwidth, typically the wavelength component included in the bandwidth with the smallest absorption and scattering, can easily pass through the resin coating RS and reach the glass portion GL, thereby making the observed images of the end faces F1 a, F2 a of the first optical fiber F1 and the second optical fiber F2 brighter and enabling the adjustment of the rotation angle θ to be performed favorably.

[0067] In this embodiment, the first light source 51 may be configured to vary the intensity of the first light L1 irradiated onto the resin coating RS of the first optical fiber F1. Similarly, the second light source 52 may be configured to vary the intensity of the second light L2 irradiated onto the resin coating RS of the second optical fiber F2. In such cases, the intensities of the first light L1 and the second light L2 can be easily adjusted. For example, if the intensities of the first light L1 and the second light L2 incident on the imaging unit 60 exceed the maximum light amount allowed by the imaging unit 60, the intensities of the first light L1 and the second light L2 can be reduced. If the intensities of the first light L1 and the second light L2 incident on the imaging unit 60 are too low, the intensities of the first light L1 and the second light L2 can be increased. Therefore, the intensity of the first light L1 emitted from the end face F1a of the first optical fiber F1 and the intensity of the second light L2 emitted from the end face F2a of the second optical fiber F2 can be appropriately adjusted to appropriately acquire observation images of the end faces F1a, F2a of the first optical fiber F1 and the second optical fiber F2. This allows the rotation angle θ to be suitably adjusted. The intensities of the first light L1 and the second light L2 may be automatically changed by the control unit 3B based on the intensities of the first light L1 and the second light L2 incident on the imaging unit 60. Alternatively, the intensities of the first light L1 and the second light L2 may be changed by an operator via an input unit such as a switch provided in the fusion splicing device 1B.

[0068] The fusion splicing device and fusion splicing method according to the present disclosure are not limited to the above-described embodiments, and various other modifications are possible. For example, the above-described embodiments may be combined with each other depending on the required purpose and effect. In the second embodiment, a common imaging unit 60 is provided for imaging the end face F1a of the first optical fiber F1 and the end face F2a of the second optical fiber F2. Separate imaging units may be provided for imaging the end face F1a and the end face F2a. In this case, the mirror 61 is not required.

[0069] DESCRIPTION OF SYMBOLS 1A, 1B... Fusion splicing device 2... Discharge electrode 3A, 3B... Control unit 11... First holding unit 12... Second holding unit 21... First driving unit 22... Second driving unit 30, 30A, 30B... Light source 31, 32... Light-emitting element 33... Tunable wavelength filter 40... Light detection unit 51... First light source 52... Second light source 60... Imaging unit 61... Mirror 111, 121... V-groove 112, 122... Base 113, 123... Cover A1... Swing direction CL... Common cladding CR... Core F1... First optical fiber F1a... End face F2... Second optical fiber F2a... End face GL... Glass portion GL1, GL2... Tip portion L... Light L1... First light L2... Second light MK... Marker RS... Resin coating θ... Rotation angle

Claims

1. A first holding part that, while holding a first optical fiber, has a glass part having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass part, and a tip portion of the glass part including an end face exposed from the resin coating, varies the rotation angle of the end face of the first optical fiber about the central axis; a second holding part that, while holding a second optical fiber, has a glass part having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass part, and a tip portion of the glass part including an end face exposed from the resin coating, varies the rotation angle of the end face of the second optical fiber about the central axis; and a light source that irradiates the resin coating of the first optical fiber, and is configured to have one or both of the following characteristics: the center wavelength of the light is tunable; and the wavelength bandwidth of the light is 100 nm or more. a light detection unit that detects the intensity of the light that leaks through the resin coating of the second optical fiber while the end face of the first optical fiber and the end face of the second optical fiber are in close proximity to each other; and a heating unit that heats the end face of the first optical fiber and the end face of the second optical fiber to melt them while they are in close proximity to each other.

2. The fusion splicing device according to claim 1, wherein the photodetector is configured so that the central wavelength of the band to which it is sensitive is variable.

3. A first holding part that holds a first optical fiber having a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion, and that changes the rotation angle of the end face of the first optical fiber about the central axis of the end face; a second holding part that holds a second optical fiber having a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion, and that changes the rotation angle of the end face of the second optical fiber about the central axis of the end face; and a first light source that irradiates the resin coating of the first optical fiber with a first light, and that is configured to have one or both of the following characteristics: the central wavelength of the first light is tunable; and the wavelength bandwidth of the first light is 100 nm or more. a second light source that irradiates the resin coating of the second optical fiber with second light and is configured to have one or both of the following characteristics: a tunable center wavelength of the second light; and a wavelength bandwidth of the second light being 100 nm or more; an imaging unit that obtains observation images of the end face of the first optical fiber and the end face of the second optical fiber; and a heating unit that heats the end face of the first optical fiber and the end face of the second optical fiber to melt the end face of the first optical fiber and the end face of the second optical fiber while they are close to each other.

4. The fusion splicing device according to claim 3, wherein the imaging unit is configured so that the center wavelength of the band to which it is sensitive is variable.

5. A fusion splicing device according to claim 1 or 2, wherein the light source is configured so that the intensity of the light irradiated onto the resin coating of the first optical fiber is variable.

6. A fusion splicing device as set forth in claim 3 or claim 4, wherein the first light source is configured so that the intensity of the first light irradiated onto the resin coating of the first optical fiber is variable, and the second light source is configured so that the intensity of the second light irradiated onto the resin coating of the second optical fiber is variable.

7. A fusion splicing method comprising the steps of: preparing a first optical fiber and a second optical fiber, each having a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion, wherein a tip portion of the glass portion including an end face is exposed from the resin coating; bringing the end face of the first optical fiber and the end face of the second optical fiber closer to each other; irradiating light onto the resin coating of the first optical fiber using a light source configured to have one or both of the following characteristics: a tunable center wavelength of output light; and a wavelength bandwidth of the output light being 100 nm or more; detecting the intensity of the light that passes through the resin coating of the second optical fiber and leaks; adjusting the relative rotation angle of the first optical fiber and the second optical fiber based on the intensity of the light detected in the detecting step; and heating and melting the end face of the first optical fiber and the end face of the second optical fiber.

8. The fusion splicing method according to claim 7, wherein said detecting step detects the intensity of said light using a photodetector configured so that the center wavelength of the band of sensitivity is variable.

9. The steps of preparing a first optical fiber and a second optical fiber, each having a glass portion having one or more cores and a cladding surrounding the one or more cores, and a resin coating surrounding the outer periphery of the glass portion, wherein a tip portion of the glass portion including an end face is exposed from the resin coating; acquiring an observation image of the end face of the first optical fiber while irradiating a first light onto the resin coating of the first optical fiber using a first light source configured to have one or both of the characteristics that the center wavelength of the output light is tunable and the wavelength bandwidth of the output light is 100 nm or more; acquiring an observation image of the end face of the second optical fiber while irradiating a second light onto the resin coating of the second optical fiber using a second light source configured to have one or both of the characteristics that the center wavelength of the output light is tunable and the wavelength bandwidth of the output light is 100 nm or more; and adjusting a relative rotation angle between the first optical fiber and the second optical fiber based on the observation image of the end face of the first optical fiber and the observation image of the end face of the second optical fiber. A fusion splicing method comprising: bringing the end face of the first optical fiber and the end face of the second optical fiber close to each other; and heating and melting the end face of the first optical fiber and the end face of the second optical fiber.

10. The fusion splicing method according to claim 9, wherein in each of the steps of acquiring an observation image of the end face of the first optical fiber and acquiring an observation image of the end face of the second optical fiber, an imaging device configured to have a variable center wavelength in a band of sensitivity is used to acquire the observation image of the end face of the first optical fiber and the observation image of the end face of the second optical fiber.

11. A fusion splicing method as described in claim 7 or claim 8, wherein in the irradiating step, the light is irradiated using a light source configured so that the intensity of the light irradiated onto the resin coating of the first optical fiber is variable.

12. A fusion splicing method as set forth in claim 9 or claim 10, wherein, in the step of obtaining an observation image of the end face of the first optical fiber, the first light is irradiated using the first light source configured to vary the intensity of the first light, and, in the step of obtaining an observation image of the end face of the second optical fiber, the second light is irradiated using the second light source configured to vary the intensity of the second light.

Images