Patent Application
20250216610
The present disclosure relates to a fiber fusion splicer and a fiber fusion splicing method. This application claims priority based on Japanese Patent Application No. 2022-049563 filed on Mar. 25, 2022, and the entire contents of the Japanese patent application are incorporated herein by reference.
As a fiber fusion splicing method, Patent Literature 1 discloses an example of a method for splicing multi-core optical fibers (hereinafter referred to as “MCF”). In general, the MCF has a plurality of cores disposed away from the central axis. Therefore, when fusion-splicing two MCFs, it is necessary to align all core positions in each of the two MCFs to be fusion-spliced, and specifically, in addition to alignment in directions along the X-axis and the Y-axis orthogonal to the Z-axis along the longitudinal direction of each MCF, rotational alignment around the Z-axis (hereinafter, referred to as “θ alignment”) is necessary. As the θ alignment method, a side observation method and an end face observation method are known. In the side observation method, side observation images of two MCFs are acquired, at least one of the MCFs is rotated around the Z-axis, and the two MCFs are aligned at an angle at which the degree of coincidence between the side observation images of the two MCFs is maximized. In the end face observation method, end face observation images of two MCFs are acquired, and the two MCFs are aligned so that the core positions between the acquired end face observation images coincide with each other.
A fiber fusion splicer of the present disclosure is a device for fusion splicing first and second MCFs each having a glass portion and a coating surrounding an outer periphery of the glass portion. The glass portion is substantially a glass optical fiber and has a plurality of cores and a common cladding surrounding the plurality of cores. The coating of each of the first and second MCFs is partially removed to expose a tip portion of the glass portion including an end face. The fiber fusion splicer, as an aspect thereof, includes a driving mechanism, an imaging device, a first illumination device, a second illumination device, and a heating device. The driving mechanism includes a first stage and a second stage. The first stage defines a position and a rotation angle of the end face of the first MCF while holding the first MCF. The second stage defines a position and a rotation angle of the end face of the second MCF while holding the second MCF. The imaging device is configured to capture an image of each of the end faces of the first and second MCFs. The first illumination device is a device that emits observation light for lateral observation to the respective coatings of the first and second MCF and includes a first side irradiation light source and a second side irradiation light source. The first side irradiation light source is configured to emit first side observation light to the coating of the first MCF. The second side irradiation light source is configured to emit second side observation light to the coating of the second MCF. The second illumination device is a device that emits the tip portion of each of the first and second MCFs with observation light for end observation and includes a first end irradiation light source and a second end irradiation light source. The first end irradiation light source is disposed away from the first MCF and is configured to emit first end observation light to the tip portion of the first MCF from which the coating is partially removed. The second end irradiation light source is disposed away from the second MCF and is configured to emit second end observation light to the tip portion of the second MCF from which the coating is partially removed. The heating device is configured to heat the end faces of the first and second MCFs to melt the end faces of the first and second MCFs with the end faces of the first and second MCFs butted against each other.
The inventors have studied the above-described conventional techniques and have found the following problems. That is, in the conventional fiber fusion splicing method, illumination light as observation light for obtaining an end face observation image is made incident from the side of an optical fiber to be spliced, and is propagated through the optical fiber for a certain distance. However, there is a problem that light propagating through a structure other than the core in the fiber, for example, a cladding or the like, is greatly attenuated, and sufficient luminance cannot be obtained at the end face. Therefore, in the case where it is necessary to grasp the relative position of the core with respect to the outer diameter of the optical fiber, the outer periphery of the optical fiber, that is, the cladding outer periphery cannot be recognized, and as a result, the relative position of the core in the optical fiber to be connected cannot be specified. Furthermore, when the coating of the optical fiber is colored, the observation light is absorbed by the ink depending on the combination of the wavelength of the observation light and the light absorption characteristics of the colored ink, and a sufficient amount of observation light is not introduced into the optical fiber, and thus, there is a problem that an end face observation image of the optical fiber to be connected including the core and the cladding cannot be obtained.
In another fiber fusion splicing method, observation light for obtaining an end face observation image is directly emitted into an optical fiber to be spliced. However, in this method, it is difficult to obtain a luminance change reflecting the refractive index distribution in the fiber end face from the end face observation image, and it is difficult to specify the position of the configuration element such as the core with respect to the outer periphery of the optical fiber.
The present disclosure has been made to solve the above-described problems, and an object of the present disclosure is to provide a fiber fusion splicer and a fiber fusion splicing method, the fiber fusion splicer having a structure for obtaining an image of a fiber end face that facilitates specifying the positions of configuration elements having different refractive indices in the fiber end face.
According to the fiber fusion splicer and the fiber fusion splicing method of the present disclosure, as an image of the fiber end face of each MCF necessary for alignment before fusion splicing between two MCFs, an image that facilitates identification of the positions of configuration elements having different refractive indices in the fiber end face is obtained.
First, the contents of embodiments of the present disclosure will be described by listing them individually.
(1) A fiber fusion splicer of the present disclosure is a device for fusion splicing first and second MCFs each having a glass portion which corresponds to a glass optical fiber and a coating surrounding an outer periphery of the glass portion. The glass portion is substantially a glass optical fiber and has a plurality of cores and a common cladding surrounding the plurality of cores. The coating of each of the first and second MCFs is partially removed to expose a tip portion of the glass portion including an end face. The fiber fusion splicer includes a driving mechanism, an imaging device, a first illumination device, a second illumination device, and a heating device. The driving mechanism includes a first stage and a second stage. The first stage defines a position and a rotation angle of the end face of the first MCF while holding the first MCF. The second stage defines a position and a rotation angle of the end face of the second MCF while holding the second MCF. The imaging device is configured to capture an image of each of the end faces of the first and second MCFs. The first illumination device is a device that emits observation light for lateral observation to the respective coatings of the first and second MCF and includes a first side irradiation light source and a second side irradiation light source. The first side irradiation light source is configured to emit first side observation light to the coating of the first MCF. The second side irradiation light source is configured to emit second side observation light to the coating of the second MCF The second illumination device is a device that emits observation light for end observation to the tip portion of each of the first and second MCFs and includes a first end irradiation light source and a second end irradiation light source. The tip portion of each of the first and second MCF corresponds to the glass portion from which the coating is removed. The first end irradiation light source is disposed away from the first MCF and is configured to emit first end observation light to the tip portion of the first MCF from which the coating is partially removed. The second end irradiation light source is disposed away from the second MCF and is configured to emit second end observation light to the tip portion of the second MCF from which the coating is partially removed. The heating device configured to heat the end faces of the first and second MCFs to melt the end faces of the first and second MCFs with the end faces of the first and second MCFs butted against each other. The glass portion corresponds to a glass optical fiber included in the MCF.
As described above, the fiber fusion splicer of the present disclosure includes a first illumination device and a second illumination device for enabling both side observation and end observation for the first MCF and the second MCF before fusion, respectively. With this configuration, the contrast between the core and the cladding and the contrast between the cladding and the image background are clear in the images of the end faces of the first MCF and the second MCF, and thus the positions of the configuration elements having different refractive indexes in the fiber end face can be easily specified.
(2) In the above (1), in the first illumination device, the first side irradiation light source is preferably disposed to come into contact with the first MCF with a microbend occurring in the coating of the first MCF. Similarly, the second side irradiation light source is preferably disposed to come into contact with the second MCF with a microbend occurring in the coating of the second MCF. This configuration allows the first side observation light and the second side observation light to be efficiently introduced into the corresponding first MCF and second MCF, specifically into the common cladding.
(3) In the above (1), the driving mechanism may further include a first bending stage and a second bending stage, the first bending stage being configured to form a bend in a section of the first MCF, the section being covered with the coating of the first MCF, the second bending stage being configured to form a bend in a section of the second MCF, the section being covered with the coating of the second MCF. Thus, the bending state in the coated parts of the first MCF and the second MCF can be maintained. In the first illumination device, the first side irradiation light source is disposed away from the first MCF to emit the first side observation light to the section of the first MCF in which the bend is formed. Similarly, the second side irradiation light source is disposed away from the second MCF to emit the second side observation light to the section of the second MCF in which the bend is formed. This configuration also allows the first side observation light and the second side observation light to be efficiently introduced into the corresponding first MCF and second MCF, specifically into both the core and the common cladding.
(4) A fiber fusion splicing method of the present disclosure is a method for fusion splicing first and second MCFs each having a glass portion and a coating surrounding an outer periphery of the glass portion. The glass portion is substantially a glass optical fiber and has a plurality of cores and a common cladding surrounding the plurality of cores. The coating of each of the first and second MCFs is partially removed to expose a tip portion of the glass portion including an end face. The fiber fusion splicing method includes, as an aspect thereof, a preparation step, a first illumination step, a second illumination step, an alignment step, and a heating step. In the preparation step, the first MCF is placed on a first stage defining a position and a rotation angle of the end face of the first MCF. Similarly, the second MCF is placed on a second stage defining a position and a rotation angle of the end face of the second MCF. In the first illumination step, the coating of the first MCF is irradiated with first side observation light from a first side irradiation light source. Similarly, the coating of the second MCF is irradiated with second side observation light from a second side irradiation light source. In the second illumination step, the tip portion of the first MCF from which the coating is partially removed is irradiated with first end observation light from a first end irradiation light source disposed away from the first MCF. Similarly, the tip portion of the second MCF from which the coating is partially removed is irradiated with second end observation light from a second end irradiation light source disposed away from the second MCF. In the imaging step, an image of each of the end faces of the first and second MCFs is captured. In the alignment step, the positions and the rotation angles of the end faces of the first and second MCFs are adjusted to make positions of the plurality of cores in the captured image of the end face of the first MCF match positions of the plurality of cores in the captured image of the end face of the second MCFs. In the heating step, the end faces of the first and second MCFs are heated to melt the end faces of the first and second MCFs with the end faces of the aligned first and second MCFs butted against each other.
As described above, in the fiber fusion splicing method of the present disclosure, the first MCF and the second MCF before fusion are irradiated with the side observation light and the end observation light for enabling both side observation and end observation. With this configuration, the contrast between the core and the cladding and the contrast between the cladding and the image background are clear in the images of the end faces of the first MCF and the second MCF, and thus the positions of the configuration elements having different refractive indexes in the fiber end face can be easily specified.
(5) In the above (4), in the first illumination step, the first side irradiation light source is preferably disposed to come into contact with the first MCF with a microbend occurring in the coating of the first MCF. Similarly, the second side irradiation light source is preferably disposed to come into contact with the second MCF with a microbend occurring in the coating of the second MCF. This configuration allows the first side observation light and the second side observation light to be efficiently introduced into the corresponding first MCF and second MCF, specifically into both the core and the common cladding.
(6) In the above (4), the first illumination device emits the lateral observation light to the first MCF and the second MCF in which bends are formed, instead of microbends. In this case, the first side irradiation light source is disposed away from the first MCF and emits the first side observation light to a section of the coating of the first MCF in which a bend is formed Similarly, the second side irradiation light source is disposed away from the second MCF and emits the second side observation light to a section of the coating of the second MCF in which a bend is formed. This configuration also makes it possible to efficiently introduce the first side observation light and the second side observation light into the corresponding first MCF and second MCF, specifically into both the core and the common cladding.
Each of the aspects listed in the “Description of Embodiments of Present Disclosure” section above is applicable to each of the remaining aspects or to all combinations of these remaining aspects.
Hereinafter, specific structures of the fiber fusion splicer and the fiber fusion splicing method of the present disclosure will be described in detail with reference to the accompanying drawings. The present disclosure is not limited to these examples, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. In the description of the drawings, the same elements are denoted by the same reference signs, and redundant description thereof will be omitted.
In the upper stage of
First MCF 100A includes a glass optical fiber 110A extending along a central axis AX as a glass portion, and a coating 120A covering an outer periphery of glass optical fiber 110A. Glass optical fiber 110A includes a plurality of cores 111 each extending along the central axis and a common cladding 112 surrounding the plurality of cores 111. Coating 120A of first MCF 100A is partially removed so that a tip portion of glass optical fiber 110A including an end face 150A corresponding to a fiber end face is exposed. As shown in the lower stage of
As a matter of course, the number of cores of first MCF 100A and the number of cores of second MCF 100B are the same. Both first MCF 100A and second MCF 100B may be provided with a marker having a refractive index different from that of common cladding 112, separately from core 111. Coating 120A and coating 120B are preferably made of resin. Further, coating 120A and coating 120B may contain a pigment or a light scattering material and may have a color under natural light. In any configuration, identification is facilitated when a plurality of MCFs are handled.
In first MCF 100A, a portion of coating 120A is held by a first stage 500A, and first stage 500A defines the position of the tip portion of first MCF 100A along a movement direction S1 parallel to the X-axis and along a movement direction S2 parallel to the Y-axis as partially of the alignment operation. Further, first stage 500A rotates first MCF 100A along a rotation direction S4 about the Z-axis as θ alignment. In addition, in the alignment operation, an observation system for performing at least one of side observation and end face observation on first MCF 100A is further provided. For example, in the case of side observation, a light source 400 and a camera 510 are disposed so as to sandwich first MCF 100A. An observation light L1 emitted from light source 400 passes through first MCF 100A and reaches camera 510. Thus, a side image of first MCF 100A is obtained. In the side observation, light source 400 and camera 510 may be disposed so as to sandwich coating 120A. On the other hand, in the case of the end face observation, an observation light L2 emitted from light source 400 propagates through first MCF 100A and reaches a camera 520. As a result, an image of end face 150A of first MCF 100A is obtained. In the end face observation, light source 400 may be disposed such that the irradiation position of observation light L2 is on the surface of coating 120A. In the alignment operation, such an observation system is also provided in the device configuration on second MCF 100B side.
In the normal alignment operation, first stage 500A adjusts the posture of first MCF 100A based on the end face observation image obtained as described above so that core 111 of first MCF 100A and core 111 of second MCF 100B coincide with each other. The posture adjustment is performed in the same manner in the device configuration on second MCF 100B side. Thereafter, as shown in the lower stage of
As shown in
Further, first MCF 100A includes glass optical fiber 110A and coating 120A provided on the outer periphery of glass optical fiber 110A. Glass optical fiber 110A is substantially made of silica glass, and includes a plurality of cores 111 and common cladding 112 surrounding the plurality of cores 111, as shown in the upper stage of
A fiber fusion splicer of the present disclosure includes a driving mechanism, an imaging device, a first illumination device, a second illumination device, and a heating device. The driving mechanism includes first stage 500A and second stage 500B. As shown in the upper stage of
The first illumination device that performs the first illumination step is a device that emits observation light to coating 120A of first MCF 100A and coating 120B of second MCF 100B, and includes a first side irradiation light source 410A and a second side irradiation light source 410B. In the example of
In fact, observation light L3a propagating under a condition confined in core 111 by reflection at the core-cladding interface gives luminance to core 111 in image 530A of end face 150A obtained by camera 530. On the other hand, observation light L3b propagating under a condition confined in common cladding 112 by reflection at the interface between common cladding 112 and coating 120A or the outside gives luminance to the common cladding in image 530A of end face 150A obtained by camera 530. However, observation light L3b has a large propagation loss due to the influence of coating 120A or the like, compared to observation light L3a. Therefore, in image 530A of end face 150A, core 111 is identified by forming a luminance difference between core 111 and common cladding 112. However, when the color of coating 120A is made dark in order to increase the discrimination between the MCFs, the propagation loss of the observation light propagating through common cladding 112 becomes excessive, and the luminance of common cladding 112 becomes too small in image 530A of end face 150A, so that it may be difficult to discriminate common cladding 112 itself. In order to solve such a problem, the fiber fusion splicer and the fiber fusion splicing method of the present disclosure include a second illumination device and a second illumination step, respectively.
The second illumination device that performs the second illumination step is a device that respectively emits observation light for end observation to the tip portion of first MCF 100A and the tip portion of second MCF 100B, and includes a first end irradiation light source 420A and a second end irradiation light source 420B. The tip portion of first MCF 100A is an exposed portion of glass optical fiber 110A from which coating 120A is removed, and the tip portion of second MCF 100B is an exposed portion of glass optical fiber 110B from which coating 120B is removed. In the example of
In the imaging step, image 530A of end face 150A is obtained based on observation lights L3a, L3b, and L4 that have reached camera 530 from end face 150A of first MCF 100A via mirror 700. Similarly, image 530B of end face 150B is obtained based on observation lights L3a, L3b, and L4 that have reached camera 530 from end face 150B of second MCF 100B via mirror 700. In the alignment step, first stage 500A and second stage 500B adjust the position and the rotation angle of end face 150A of first MCF 100A and end face 150B of second MCF 100B so that the core positions of images 530A and 530B captured by camera 530 match each other. It is noted that, in order to improve the detection accuracy of the position and the rotation direction of first MCF 100A and second MCF 100B, another camera capable of capturing a side image of first MCF 100A and second MCF 100B may be disposed.
In the first illumination step, the second illumination step, and the imaging step described above, core 111 and common cladding 112 are identified, and in the alignment step, the positions and the rotation directions of first MCF 100A and second MCF 100B are adjusted. Thereafter, after mirror 700 is retracted together with all the light sources 410A, 410B, 420A, and 420B, discharge electrodes 600A and 600B included in the heating device are arranged under a condition where end face 150A of first MCF 100A and end face 150B of second MCF 100B are butted against each other.
In addition, the fiber fusion splicer of the present disclosure in the fusing operation includes a heating device, and the heating device includes discharge electrodes 600A and 600B as shown in the lower stage of
In the upper stage of
In the lower stage of
For first MCF 100A in which the bending is formed as described above, first side irradiation light source 410A of the first illumination device is disposed away from coating 120A of first MCF 100A, and emits side observation light to the section of first MCF 100A in which the bending is formed in a non-contact state. This configuration is the same as the device configuration on second MCF 100B side. The observation light introduced from first side irradiation light source 410A to glass optical fiber 110A via coating 120A is divided into observation light L3a propagating in core 111 and observation light L3b propagating in common cladding 112, and observation light L3a and observation light L3b are emitted from end face 150A toward camera 530.
In the device configuration disclosed in both the upper stage and the lower stage of
The device configuration shown in the upper stage of
In the device configuration of comparative example 1 shown in the upper stage of
On the other hand, in the device configuration of comparative example 2 shown in the lower stage of
In the following description, the luminance average values of core 111, common cladding 112, and the background are referred to as “core luminance”, “cladding luminance”, and “background luminance”, respectively. The standard deviations of the luminance variations with time in core 111, common cladding 112, and the background are referred to as “core luminance noise”, “cladding luminance noise”, and “background luminance noise”, respectively.
Specifically, the core SN ratio is calculated by the following formula (1):
As can be seen from the graph of
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-049563 | Mar 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/010669 | 3/17/2023 | WO |
