JP2013054116A - Method for coupling multi-core fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for coupling multi-core fibers for suppressing deterioration of coupling efficiency by simple configurations.SOLUTION: A method for coupling multi-core fibers has: a first alignment process; a first measurement process; second alignment process; and a fusion process. In the first alignment process, alignment in a direction perpendicular to a long axis of the multi-core fibers is performed by relatively moving the multi-core fibers. In the first measurement process, light is input in a first core of one multi-core fiber, and intensity of the light transmitted to a first core of the other multi-core fiber is measured. In the second alignment process, alignment in the rotation direction is performed by relatively rotating the multi-core fibers in its rotation direction based on the intensity of the light measured in the first measurement process. In the fusion process, the end surface of one multi-core fiber and the end surface of the other multi-core fiber are fused together after the second alignment process is performed.

Description

  The present invention relates to a method for coupling multi-core fibers used for optical communication and the like.

  With the spread of smartphones and tablet terminals, communication of data having an enormous amount of information is required. Accordingly, further increase in capacity of optical communication is desired.

  Conventional optical communication is performed using a single core fiber in which one core is provided in a clad. However, since there is a capacity limit when communication is performed using one single core fiber, means for performing data communication with a capacity exceeding the capacity is required.

  In this regard, for example, a multi-core fiber that is an optical fiber in which a plurality of cores are provided in one clad can be used (see Patent Documents 1 and 2). Since the multi-core fiber has a plurality of cores, it is possible to perform large-capacity data communication compared to the single-core fiber. In optical communication, there is a demand for using such multi-core fibers in combination.

  Here, in order to transmit light between fibers, it is necessary to securely couple the cores. Therefore, it is important to align the fibers (cores).

  For example, when a single core fiber having a core arranged at the center is coupled to each other, by using a positioning member such as a ferrule, the position of the fiber in the two directions perpendicular to the major axis direction and the major axis direction is uniquely determined. The Therefore, the cores can be reliably bonded to each other.

  On the other hand, in the case of a multi-core fiber, since a plurality of cores are arranged in addition to the center, not only the alignment in two directions orthogonal to the major axis direction and the major axis direction, but also the rotational direction (the outer peripheral direction of the multi-core fiber) Alignment is also required. Therefore, it is difficult to reliably connect the cores only by positioning using the ferrule.

  Moreover, there are Patent Document 3 and Patent Document 4 as techniques for aligning single core fibers.

  Specifically, in the technique described in Patent Document 3, two PCFs (Photonic Crystal Fibers) [1, 1] are fixed to the holding members [21, 21] so that the end faces [5, 5] face each other. Hold. The end faces [5, 5] are copied to the mirror [22] and observed by the camera [24], and the image is processed by the image processing device [25] to confirm both core positions. Then, according to the information on the core position, each first drive unit [26] is finely moved to adjust so that both cores exist on the same axis. Then, the end faces [5, 5] are brought close together to make a fusion connection.

  Patent Document 4 describes that the core is photographed from the outside of the optical fiber and the state of the core is observed with the photographed image in order to perform alignment and judge the quality of the core end face before the fusion splicing of the optical fiber. ing. Therefore, based on the captured image, the fibers can be butted and fused so that the end faces of the cores coincide with each other.

JP-A-10-104443 JP-A-8-119656 JP 2004-53625 A JP 2000-146751 A

  However, in the technique of Patent Document 3, it is necessary to secure a space for placing the mirror [22] between the fibers. Therefore, the configuration is complicated.

  Further, since a multi-core fiber is provided with a plurality of cores, a slight deviation greatly affects the coupling efficiency. Here, in the technique of Patent Document 3, when the fiber end faces are coupled to each other, the mirror [22] must be removed from between the fibers, and the fiber must be moved by the size of the mirror [22]. Therefore, the process until the fibers are coupled and the amount of movement of the fibers increase. Therefore, there is a high possibility that misalignment occurs between the multi-core fibers, and the coupling efficiency is likely to decrease.

  Furthermore, even if alignment is performed only with images as in Patent Document 4, it is difficult to grasp an accurate position due to fiber distortion or the like. In a multi-core fiber having a plurality of cores, the effect is large, and in fact, there is a high possibility that a misalignment between multi-core fibers occurs. Therefore, the coupling efficiency is likely to be reduced.

  The present invention solves the above-described problems, and an object of the present invention is to provide a multicore fiber coupling method capable of suppressing a decrease in coupling efficiency with a simple configuration.

In order to solve the above-mentioned problem, a multi-core fiber coupling method according to claim 1 is a method of coupling multi-core fibers in which a plurality of cores are covered with a clad. The coupling method includes a first alignment process, a first measurement process, a second alignment process, and a fusion process. In the first alignment step, one multicore fiber and the other multicore fiber are aligned in a direction orthogonal to the major axis by relatively moving one multicore fiber and the other multicore fiber. In the first measurement step, light is input to the first core of one multicore fiber, and the intensity of the light transmitted to the first core of the other multicore fiber is measured. In the second alignment step, one multicore fiber in the rotation direction is rotated by relatively rotating one multicore fiber and the other multicore fiber in the rotation direction based on the intensity of light measured in the first measurement step. Is aligned with the other multi-core fiber. In the fusion process, after the second alignment process is performed, the end face of one multicore fiber and the end face of the other multicore fiber are fused.
In order to solve the above-mentioned problem, the multicore fiber coupling method according to claim 2 is the multicore fiber coupling method according to claim 1, wherein the first alignment step includes: One multicore fiber and the other multicore fiber are moved relative to each other so that the end face of the other multicore fiber coincides with the direction perpendicular to the major axis direction of the multicore fiber. The multi-core fiber is aligned with the other multi-core fiber.
In order to solve the above problems, a multicore fiber coupling method according to a third aspect is the multicore fiber coupling method according to the first aspect, wherein the first alignment step includes a second measurement step. In the second measurement step, light is input to the second core of one multicore fiber, and the intensity of the light transmitted to the second core of the other multicore fiber is measured. In the first alignment step, the one multicore fiber and the other multicore fiber are relatively moved in the direction perpendicular to the long axis direction based on the light intensity measured in the second measurement step, thereby Alignment between one multicore fiber and the other multicore fiber in a direction orthogonal to is performed.
In order to solve the above problem, a multicore fiber coupling method according to claim 4 is the multicore fiber coupling method according to claim 3, wherein the second core is a core disposed at the center of the multicore fiber. It is.
In order to solve the above problem, a multicore fiber coupling method according to claim 5 is the multicore fiber coupling method according to any one of claims 1 to 4, wherein the first core is formed of a multicore fiber. It is a core arranged at a position closest to the outer periphery.
In order to solve the above problem, a multicore fiber coupling method according to claim 6 is a method of coupling multicore fibers in which a plurality of cores are covered with a clad. The coupling method includes a measurement process, an alignment process, and a fusion process. In the measurement step, light is input to the first core and the second core of one multicore fiber, and the intensity of the light transmitted to the first core and the second core of the other multicore fiber is measured. In the alignment process, based on the light intensity measured in the measurement process, one multi-core fiber and the other multi-core fiber are moved relative to each other in the direction perpendicular to the long axis direction and in the rotation direction. The alignment of one multicore fiber and the other multicore fiber in the orthogonal direction and the rotation direction is performed. In the fusion process, after the alignment process is performed, the end face of one multicore fiber and the end face of the other multicore fiber are fused.
In order to solve the above problem, a multicore fiber coupling method according to claim 7 is the multicore fiber coupling method according to claim 6, wherein at least one of the first core and the second core is a multicore fiber. It is the core arrange | positioned in the position nearest to the outer periphery.

  Align the multi-core fibers in the direction perpendicular to the long axis direction of the multi-core fiber, and then transmit the light from the core of one multi-core fiber and transmit the light to the core of the other multi-core fiber. Measure the intensity. Then, based on the measured light intensity, the one multi-core fiber and the other multi-core fiber are rotated relative to each other in the rotation direction to perform alignment in the rotation direction. Therefore, when coupling multi-core fibers, it is possible to suppress a decrease in coupling efficiency with a simple configuration.

It is a figure which shows the multi-core fiber common to embodiment. It is a figure which shows the flowchart which concerns on 1st Embodiment. It is a figure which supplements the flowchart which concerns on 1st Embodiment. It is a figure which supplements the flowchart which concerns on 1st Embodiment. It is a figure which supplements the flowchart which concerns on 1st Embodiment. It is a figure which supplements the flowchart which concerns on 1st Embodiment. It is a figure which shows the flowchart which concerns on 2nd Embodiment. It is a figure which supplements the flowchart which concerns on 2nd Embodiment. It is a figure which supplements the flowchart which concerns on 2nd Embodiment. It is a figure which supplements the flowchart which concerns on 2nd Embodiment. It is a figure which shows the flowchart which concerns on 3rd Embodiment. It is a figure which supplements the flowchart which concerns on 3rd Embodiment.

[Configuration of multi-core fiber]
With reference to FIG. 1, the structure of the multi-core fiber 1 common to embodiment is demonstrated. The multi-core fiber 1 is generally a long cylindrical member having flexibility. FIG. 1 is a perspective view of the multi-core fiber 1. In FIG. 1, only the tip portion of the multi-core fiber 1 is shown. Hereinafter, the major axis direction of the multi-core fiber 1 will be described as an X direction, and two directions orthogonal to the major axis direction will be described as a Y direction and a Z direction, respectively.

The multi-core fiber 1 is made of a material having a high light transmittance such as quartz glass or plastic. The multicore fiber 1 includes a plurality of cores C _k (k = 1 to n) and a clad 2.

The core C _k is a transmission path for transmitting light from a light source (not shown). Each of the cores C _k has an end face E _k (k = 1 to n). From the end surface E _k, the light source light emitted by the (not shown) is emitted. Light emitted from the core C _k includes a principal ray. In order to increase the refractive index as compared with the clad 2, the core C _k is made of a material in which germanium oxide (GeO ₂ ) is added to, for example, quartz glass. Although FIG. 1 shows a configuration having _seven cores C _{1 to} C ₇ , the number of cores C _k may be at least two.

The clad 2 is a member that covers the plurality of cores _Ck . Cladding 2 has a function to confine light from a light source (not shown) in the core C _k. The clad 2 has an end face 2a. The end surface _Ek of the core _Ck and the end surface 2a of the clad 2 form the same surface (the end surface 1b of the multicore fiber 1). The cladding 2 material, a low refractive index material is used than the core C _k material. For example, when the material of the core C _k is made of quartz glass and germanium oxide, quartz glass is used as the material of the clad 2. Thus, by making the refractive index of the core C _k higher than the refractive index of the cladding 2, the light from the light source (not shown) is totally reflected at the interface between the core C _k and the cladding 2. Therefore, light can be transmitted in the core _Ck . The clad 2 may be formed of a transparent material. In this case, the core C _k covered with the clad 2 is visible from the outside.

<First Embodiment>
Next, with reference to FIG. 2 to FIG. 6, a method for coupling multi-core fibers according to the first embodiment will be described. Here, the multi-core fiber 1 having seven cores _C 1 -C _7, description will be given of a case where coupling the multicore fiber 1 'having seven core _{C'1 ~C' 7.}

FIG. 2 is a flowchart of the combining method according to the first embodiment. 3, 5, and 6 are cross-sectional views of the multicore fiber 1 and the multicore fiber 1 ′ in the X direction. 3, 5, 6, three cores of the multicore fiber _{1 (C 1, C 2,} C 5), and three cores of the multicore fiber _{1'(C'1, C'2,} C'5) Only shows. 4 is a view showing the end face 1b of the multi-core fiber 1 (a view of the multi-core fiber 1 viewed from the X direction (arrow A in FIG. 3)). It is assumed that the multicore fiber 1 and the multicore fiber 1 ′ have the same diameter, core diameter, and core arrangement. The multi-core fiber 1 in the present embodiment is an example of “one multi-core fiber”. The multicore fiber 1 ′ is an example of “the other multicore fiber”.

  First, two multi-core fibers 1 and 1 ′ are arranged so that their end faces 1b and 1b ′ face each other (S10, see FIG. 3). The arrangement of the multicore fiber 1 (1 ′) is performed, for example, by holding the multicore fiber 1 (1 ′) in a holding device (not shown).

  Next, the interval S between the opposed multi-core fibers is adjusted (S11). Specifically, while viewing an image obtained by photographing the end face 1b (1b ') of the multicore fiber 1 (1') with a camera (not shown), the end face of one multicore fiber until the interval S reaches a predetermined value. The end surface (for example, end surface 1b ′) of the other multicore fiber is brought closer to (for example, the end surface 1b). Thereby, the end surfaces of the multi-core fibers can be arranged close to each other (for example, several microns).

The “predetermined value” is the multi-core fiber 1 ′ while maintaining the intensity of the light input to the core C _k of the multi-core fiber 1 when the alignment of the rotation directions of the multi-core fibers (see S13 described later) is completed. is a value which can be transmitted to the core _C'k (intervals of the multi-core fiber 1 and the multi-core fiber 1 ').

  The step of S11 is executed by moving the multi-core fiber manually or automatically. For example, an instruction is input at an input unit (not shown) or the like, and based on the instruction input, a control device (not shown) moves a holding device (not shown) to bring the multi-core fibers close to each other. Then, the control device (not shown) compares the predetermined value stored in advance with the movement amount of the holding device (not shown), and stops the movement of the holding device (not shown) when the predetermined value is reached. In step S11, the distance S may be adjusted by moving both multi-core fibers.

  Here, when the multi-core fibers are opposed to each other, there is a possibility that a deviation occurs in the Y direction and the Z direction (an arrow D in FIG. 3 indicates a deviation in the Z direction). Therefore, next, alignment in the Y direction and the Z direction is performed (S12). In addition, since the same method can be used for the alignment in the Y direction and the alignment in the Z direction, the alignment in the Z direction will be described below.

  For alignment in the Z direction, for example, the end surface 1b (1b ') of the multi-core fiber 1 (1') is photographed from the Y direction with a camera (not shown). Then, while confirming the obtained image, the multi-core fiber 1 ′ is moved in the Z direction until the deviation D disappears (until the end surface 1b and the end surface 1b ′ coincide with each other in the Z direction).

  The step of S12 is executed by moving the multi-core fiber manually or automatically. For example, an instruction is input at an input unit (not shown) or the like, and based on the instruction input, a control device (not shown) moves a holding device (not shown) to perform alignment in the Y direction and the Z direction. . In the step of S12, the alignment in the Y direction and the Z direction may be performed by moving both multi-core fibers.

  Furthermore, alignment in the Y direction and the Z direction by image analysis is also possible. For example, the inclination angle in the XZ direction of the end face 1b (1b ′) of one multicore fiber is analyzed by an analysis device (not shown). Then, based on the analysis result, the control device (not shown) moves the holding device (not shown), and the other multi-core fiber is tilted by the same tilt angle as that, thereby enabling alignment.

  In addition, the analysis device (not shown) detects the position of the edge of the multicore fiber 1 (edge formed by the end surface 1b and the side surface 2b) and the edge of the multicore fiber 1 ′ (edge formed by the end surface 1b ′ and the side surface 2b ′) from the obtained image. ) Position. Then, based on the analysis result, the control device (not shown) can be positioned by moving the holding device so that the respective edges coincide in the Z direction.

  By S12, the alignment of the multi-core fibers in the Y direction and the Z direction is completed. Note that either step of S11 and S12 may be performed first. S12 in the present embodiment is an example of a “first alignment step”.

Here, in the connection between the multicore fibers, even if the alignment in the Y direction and the Z direction is performed, the positions of the cores may be shifted in the rotation direction of the multicore fibers (FIG. 4). (Refer to θ indicates the deviation in the rotation direction). The dotted line in FIG. 4 shows an example of the multi-core fiber 1 ′ and the core C ′ _k that have been aligned with respect to the multi-core fiber 1 in the Y direction and the Z direction.

If to eliminate the deviation in the rotational direction, the light from the core C _k, it is difficult to transmit while keeping the coupling efficiency to the core _C'k. For example, in the state of FIG. 4, the light emitted from the core _{C 2} strikes the cladding 2 'of the multicore fiber 1', core _C'k (e.g., core _C'2) is not transmitted to. Therefore, after S12, alignment in the rotational direction is performed (S13).

In this case, as shown in FIG. 5, first, light (see the broken line arrow in FIG. 5) is input to an arbitrary first core C _k . On the other hand, any exit end of the first core _C'k of the multi-core fiber 1 ', to connect the power meter 100. The power meter 100 is a device that measures the intensity of light transmitted to the first core C ′ _k . First core _{C k} in this embodiment is the core _{C 2.} The first core C ′ _k is C ′ ₂ .

In such a state, the multicore fiber 1 ′ is rotated in the rotation direction with respect to the multicore fiber 1. Thus when light from the core C ₂ is transmitted to the core _C'2 can measure the intensity of light with a power meter 100. When the end faces of the cores are completely coincident with each other, the light intensity is maximized. Therefore, the position where the intensity is maximized is specified while rotating the multi-core fiber. In step S13, both the multi-core fibers can be rotated.

  The rotation in the rotation direction can be performed manually or automatically while confirming the intensity of light obtained by the power meter 100. For example, the intensity of light is detected by a detection device (not shown) or the like. The control device (not shown) rotates the multi-core fiber held by the holding device while comparing the detected intensity with the maximum intensity stored in advance. Note that the light intensity does not necessarily have to be the maximum, and may be any light intensity that enables desired optical communication. That is, the intensity of light that can transmit necessary information is sufficient.

  By the step of S13, alignment in the rotation direction becomes possible. S13 in this embodiment is an example of a “first measurement process” and a “second alignment process”.

Incidentally, it is possible to increase the shift amount when performing alignment by transmitting the light from the core disposed at a position closest to the outer periphery of the multi-core fiber 1 as the core C ₂ (rotation amount). Therefore, alignment in the rotation direction is facilitated. In the present embodiment, a predetermined interval is provided between the multicore fiber 1 and the multicore fiber 1 ′. Therefore, when positioning in the rotation direction is performed, there is a low possibility that the end faces of the multicore fibers are in contact with each other. Therefore, the end face is not easily damaged.

  Thereafter, the multi-core fiber 1 ′ is moved in the X direction, and the end face 1 b ′ of the multi-core fiber 1 ′ is brought into contact with the end face 1 b of the multi-core fiber 1. Then, thermal discharge is performed on the contacted portion, and the end surfaces of the multicore fibers are melted to join the multicore fibers (S14, see FIG. 6). S14 in the present embodiment is an example of a “fusion process”. In addition, in the step of S14, the end faces may be brought into contact with each other by moving both multi-core fibers. In this embodiment, since the space between the multicore fiber 1 and the multicore fiber 1 ′ is very small (for example, several microns), when the multicore fiber 1 ′ is moved, the positions in the Y direction, the Z direction, and the rotation direction The possibility of deviation is low.

  The alignment in the X direction in the present embodiment is achieved by moving the end face 1b ′ of the multicore fiber 1 ′ to the position of the end face 1b of the multicore fiber 1 in S14. That is, the position in the X direction is arbitrarily determined depending on the position where the multi-core fiber 1 is held.

  In the present embodiment, the case where the light input to the multicore fiber 1 is transmitted to the multicore fiber 1 ′ has been described, but the rotation direction alignment is achieved by transmitting the light input to the multicore fiber 1 ′ to the multicore fiber 1. It is also possible to perform.

[Action / Effect]
The operation and effect of this embodiment will be described.

  The coupling method according to the present embodiment is a method of coupling multi-core fibers in which a plurality of cores are covered with a clad. The bonding method includes a first alignment process, a first measurement process, a second alignment process, and a fusion process. In the first alignment step, the multi-core fiber 1 and the multi-core fiber 1 ′ are aligned in a direction orthogonal to the major axis by relatively moving the multi-core fiber 1 and the multi-core fiber 1 ′. In the first measurement step, light is input to the first core of the multicore fiber 1 and the intensity of the light transmitted to the first core of the multicore fiber 1 ′ is measured. In the second alignment step, the multicore fiber 1 and the multicore in the rotation direction are rotated by relatively rotating the multicore fiber 1 and the multicore fiber 1 ′ in the rotation direction based on the light intensity measured in the first measurement step. Alignment with the fiber 1 'is performed. In the fusion process, after the second alignment process is performed, the end surface 1b of the multicore fiber 1 and the end surface 1b ′ of the multicore fiber 1 ′ are fused.

  In the first alignment step according to the present embodiment, the multicore fiber 1 and the multicore fiber are arranged so that the end surface 1b of the multicore fiber 1 and the end surface 1b ′ of the multicore fiber 1 ′ coincide with each other in the direction orthogonal to the major axis direction of the multicore fiber. By relatively moving 1 ′, the multi-core fiber 1 and the multi-core fiber 1 ′ are aligned in a direction orthogonal to the long axis.

  Thus, alignment in the Y direction and the Z direction is performed by matching the end face 1b of the multicore fiber 1 with the end face 1b 'of the multicore fiber 1'. And based on the intensity | strength of the light measured by the measurement process, the multi-core fiber 1 and multi-core fiber 1 'are rotated relatively in the rotation direction, and the alignment of the rotation direction of the multi-core fiber 1 and the multi-core fiber 1' is performed. In this case, alignment of the multi-core fibers in the Y direction, the Z direction, and the rotation direction can be reliably performed. Therefore, when coupling multi-core fibers, it is possible to suppress a decrease in coupling efficiency.

In the present embodiment, the core of the multicore fiber 1 to which light is input in the first measurement process is the core (C ₂ ) disposed at a position closest to the outer periphery of the multicore fiber 1.

  In this way, the amount of rotation can be increased by inputting light to the core disposed at the position closest to the outer periphery of the multi-core fiber and performing alignment in the rotation direction based on the light. Therefore, alignment becomes easy.

Second Embodiment
Next, with reference to FIGS. 7 to 10, a method for coupling multi-core fibers according to the second embodiment will be described. Here, the multi-core fiber 1 having seven cores _C 1 -C _7, description will be given of a case where coupling the multicore fiber 1 'having seven core _{C'1 ~C' 7.} Detailed descriptions of the same parts as those in the first embodiment may be omitted.

FIG. 7 is a flowchart of the combining method according to the second embodiment. 8 and 10 are cross-sectional views in the X direction of the multicore fiber 1 and the multicore fiber 1 '. 8 and 10, three cores of the multicore fiber _{1 (C 1, C 2,} C 5), and three cores of the multicore fiber _{1'(C'1, C'2,} C'5) shows only ing. FIG. 9 is a view showing the end face 1b of the multicore fiber 1 (a view of the multicore fiber 1 viewed from the X direction (arrow A in FIG. 8)). It is assumed that the multicore fiber 1 and the multicore fiber 1 ′ have the same diameter, core diameter, and core arrangement. The multi-core fiber 1 in the present embodiment is an example of “one multi-core fiber”. The multicore fiber 1 ′ is an example of “the other multicore fiber”.

  First, the two multi-core fibers 1 and 1 ′ are arranged such that the end faces 1b and 1b ′ face each other (S20). Next, the spacing S between the opposed multi-core fibers is adjusted, and the end faces of the multi-core fibers are arranged close to each other (for example, several microns) (S21).

  Here, when the multi-core fibers are opposed to each other, there is a possibility that a deviation occurs in the Y direction and the Z direction (an arrow D in FIG. 8 indicates a deviation in the Z direction). Therefore, next, alignment in the Y direction and the Z direction is performed (S22).

In the alignment in the Y direction and the Z direction in this embodiment, as shown in FIG. 8, first, light (see the broken line arrow in FIG. 8) is input to an arbitrary second core C _k . On the other hand, any exit end of the second core _C'k of the multi-core fiber 1 ', to connect the power meter 100. Second core _{C k} in this embodiment is the core _{C 2.} The second core C ′ _k is C ′ ₂ .

In such a state, the multicore fiber 1 ′ is moved in the Y direction and the Z direction with respect to the multicore fiber 1. Thus when light from the core C ₂ is transmitted to the core _C'2 can measure the intensity of light with a power meter 100. When the end faces of the cores are completely coincident with each other, the light intensity becomes maximum. Therefore, the position where the intensity becomes maximum is specified while moving the multi-core fiber 1 ′. In step S22, both multi-core fibers can be moved.

  The movement in the Y direction and the Z direction can be performed manually or automatically while checking the intensity of light obtained by the power meter 100. For example, the intensity of light is detected by a detection device (not shown) or the like. The control device (not shown) moves the multi-core fiber 1 ′ held by the holding device while comparing the detected intensity with the maximum intensity stored in advance. Note that the light intensity does not necessarily have to be the maximum, and may be any light intensity that enables desired optical communication. That is, the intensity of light that can transmit necessary information is sufficient.

  By the step of S22, the alignment in the Y direction and the Z direction is completed. Note that either step of S21 and S22 may be performed first. S22 in the present embodiment is an example of a “second measurement process” and a “first alignment process”.

Here, in the connection between the multi-core fibers, even if the alignment in the Y direction and the Z direction is performed, the positions of the cores may be shifted in the rotation direction of the multi-core fibers (FIG. 9). (Refer to θ indicates the deviation in the rotation direction). The dotted lines in FIG. 9 show an example of the multi-core fiber 1 ′ and its core C ′ _k that have been aligned with respect to the multi-core fiber 1 in the Y direction and the Z direction.

If to eliminate the deviation in the rotational direction, the light from the core C _k, it is difficult to transmit while keeping the coupling efficiency to the core _C'k. For example, in the state of FIG. 9, the light emitted from the core _{C 5} strikes the cladding 2 'of the multicore fiber 1', core _C'k (e.g., core _C'5) is not transmitted to. Therefore, after S22, alignment in the rotational direction is performed (S23).

In this case, as shown in FIG. 10, light (see the broken line arrow in FIG. 10) is input to an arbitrary first core C _k . On the other hand, any exit end of the first core _C'k of the multi-core fiber 1 ', to connect the power meter 100. First core _{C k} in this embodiment, the core _{C 5.} Further, the first core C ′ _k is C ′ ₅ .

In such a state, the multi-core fiber 1 ′ is rotated in the rotation direction with respect to the multi-core fiber 1 with the long axis of the core C ₂ (C ′ ₂ ) aligned in S22 as a reference. Thus when light from the core C ₅ is transmitted to the core _C'5 can measure the intensity of light with a power meter 100. When the end faces of the cores are completely coincident with each other, the light intensity is maximized. Therefore, the position where the intensity is maximized is specified while rotating the multi-core fiber. In step S23, both the multi-core fibers can be rotated.

  The rotation in the rotation direction can be performed manually or automatically while confirming the intensity of light obtained by the power meter 100. For example, the intensity of light is detected by a detection device (not shown) or the like. The control device (not shown) rotates the multi-core fiber held by the holding device while comparing the detected intensity with the maximum intensity stored in advance. Note that the light intensity does not necessarily have to be the maximum, and may be any light intensity that enables desired optical communication. That is, the intensity of light that can transmit necessary information is sufficient.

By the step of S23, alignment in the rotation direction becomes possible. S23 in the present embodiment is an example of a “first measurement process” and a “second alignment process”. Note that it is possible to greatly shifted amount when performing alignment by transmitting the light from the nearest place to position cores on the outer periphery of the multi-core fiber 1 as the core C ₅ (rotation amount). Therefore, alignment in the rotation direction is facilitated. Further, the step of S23 may be performed in a state where the intensity of light transmitted to the core C′2 is detected by the power meter 100 (state of S22).

  Thereafter, the multi-core fiber 1 ′ is moved in the X direction, and the end face 1 b ′ of the multi-core fiber 1 ′ is brought into contact with the end face 1 b of the multi-core fiber 1. Then, thermal discharge is performed on the contacted portion, and the end surfaces of the multicore fibers are melted to join the multicore fibers (S24). S24 in the present embodiment is an example of a “fusion process”. In addition, in the step of S24, the end faces may be brought into contact with each other by moving both multi-core fibers.

  The alignment in the X direction in the present embodiment is achieved by moving the end face 1b ′ of the multicore fiber 1 ′ to the position of the end face 1b of the multicore fiber 1 in S24. That is, the position in the X direction is arbitrarily determined depending on the position where the multi-core fiber 1 is held.

Incidentally, in the case of adjusting the position of Y and Z directions, disposed second core C _k for inputting light _(the second core C'k connecting the power meter ₁₀₀₎ in the center of the multi-core fiber 1 (1 ') It is preferable to use a core (in this embodiment, core C ₁ ).

By performing alignment in the Y direction and Z direction with reference to the core C ₁ disposed at the center of the multi-core fiber 1, it is difficult for the coupling efficiency of the core C ₁ to change when alignment in the rotation direction is performed. That is, since the rotation axis center when rotating the multi-core fiber can be easily obtained, alignment in the rotation direction is facilitated. Moreover, it is easy to couple | bond arbitrary cores by rotating on the basis of a center core. For example, when performing positioning in the rotational direction relative to the core C _{1 (C'1),} to it is also possible to bond the core C ₂ core _C'2, the other core, for example core _C'5 And the core C ₂ can be combined.

  In the present embodiment, the case where the light input to the multicore fiber 1 is transmitted to the multicore fiber 1 ′ is described. However, the light input to the multicore fiber 1 ′ is transmitted to the multicore fiber 1 in the Y direction, It is also possible to perform alignment in the Z direction and the rotation direction.

[Action / Effect]
The operation and effect of this embodiment will be described.

  The first alignment process according to the present embodiment includes a second measurement process. In the second measurement step, light is input to the second core of the multicore fiber 1 and the intensity of the light transmitted to the second core of the multicore fiber 1 ′ is measured. In the first alignment step, the multi-core fiber 1 and the multi-core fiber 1 ′ are moved relative to each other in the direction perpendicular to the major axis direction based on the light intensity measured in the second measurement step. The multi-core fiber 1 and the multi-core fiber 1 ′ are aligned in the orthogonal direction.

  Thus, based on the light intensity measured in the second measurement step, the multi-core fiber 1 and the multi-core fiber 1 ′ are aligned in the Y direction and the Z direction. Then, based on the light intensity measured in the first measurement step, the multi-core fiber 1 and the multi-core fiber 1 ′ are relatively rotated in the rotation direction, and the multi-core fiber 1 and the multi-core fiber 1 ′ are aligned in the rotation direction. . In this case, alignment of the multi-core fibers in the Y direction, the Z direction, and the rotation direction can be reliably performed. Therefore, when coupling multi-core fibers, it is possible to suppress a decrease in coupling efficiency.

  In the present embodiment, the second core is a core disposed at the center of the multicore fiber.

  As described above, the center of the rotation axis can be easily obtained by using the core disposed at the center of the multi-core fiber as a reference. Therefore, alignment in the rotation direction is facilitated. Moreover, it becomes possible to couple | bond arbitrary cores by rotating on the basis of a center core.

In the present embodiment, the core of the multi-core fiber 1 to which light is input in the first measurement process is the core (C ₅ ) disposed at a position closest to the outer periphery of the multi-core fiber 1.

  In this way, the amount of rotation can be increased by inputting light to the core disposed at the position closest to the outer periphery of the multi-core fiber and performing alignment in the rotation direction based on the light. Therefore, alignment becomes easy.

<Third Embodiment>
Next, with reference to FIG.11 and FIG.12, the coupling | bonding method of the multi-core fibers which concern on 3rd Embodiment is demonstrated. Here, the multi-core fiber 1 having seven cores _C 1 -C _7, description will be given of a case where coupling the multicore fiber 1 'having seven core _{C'1 ~C' 7.} Detailed description of the same parts as those in the first and second embodiments may be omitted.

FIG. 11 is a flowchart of the combining method according to the third embodiment. FIG. 12 is a cross-sectional view of the multi-core fiber 1 and the multi-core fiber 1 ′ in the X direction. In Figure 12, three cores of the multicore fiber _{1 (C 1, C 2,} C 5), and three cores of the multicore fiber _{1'(C'1, C'2,} C'5) shows only. It is assumed that the multicore fiber 1 and the multicore fiber 1 ′ have the same diameter, core diameter, and core arrangement. The multi-core fiber 1 in the present embodiment is an example of “one multi-core fiber”. The multicore fiber 1 ′ is an example of “the other multicore fiber”.

  First, the two multi-core fibers 1 and 1 ′ are arranged so that the end faces 1b and 1b ′ face each other (S30). Next, the spacing S between the opposed multi-core fibers is adjusted, and the end faces of the multi-core fibers are arranged close to each other (for example, several microns) (S31).

  Here, when the multi-core fibers are opposed to each other, there is a possibility that a deviation occurs in the Y direction, the Z direction, and the rotation direction. Therefore, alignment in the Y direction, the Z direction, and the rotation direction is performed (S32).

As shown in FIG. 12, first, light (see the broken line arrow in FIG. 12) is input to each of the arbitrary first core C _k and the arbitrary second core C _k of the multicore fiber 1. On the other hand, the power meter 100 is connected to the emission ends of the arbitrary first core C ′ _k and the optional second core C ′ _k of the multi-core fiber 1 ′. The first core C _k in the present embodiment is the core C ₂ that is disposed at a position closest to the outer periphery of the multi-core fiber 1. The second core C _k is a core C ₅ that is disposed at a position closest to the outer periphery of the multi-core fiber 1 ′. The first core C ′ _k is the core C ′ ₂ . The second core C ′ _k is the core C ′ ₅ .

In such a state, the multicore fiber 1 ′ is moved in the Y direction and the Z direction with respect to the multicore fiber 1 or rotated in the rotation direction. Thus when light from the core _{C 2} (core _{C 5)} is transmitted to the core _C'2 (core _C'5) is capable of measuring the intensity of light with a power meter 100. When the end faces of the cores are completely coincident with each other, the intensity of light is maximized. Therefore, the positions where the intensity is maximized in each of the cores C ′ ₂ and C ′ ₅ while moving the multi-core fiber 1 ′. Is identified. In step S32, both the multi-core fibers can be moved.

  By the step of S32, the alignment in the Y direction, the Z direction, and the rotation direction is completed. Note that either step of S31 and S32 may be performed first. S32 in this embodiment is an example of a “measurement step” and a “positioning step”.

  Thereafter, the multi-core fiber 1 ′ is moved in the X direction, and the end face 1 b ′ of the multi-core fiber 1 ′ is brought into contact with the end face 1 b of the multi-core fiber 1. Then, thermal discharge is performed on the contacted portion, and the end surfaces of the multicore fibers are melted to join the multicore fibers (S33). S33 in the present embodiment is an example of a “fusion process”. In the step of S33, the end faces may be brought into contact with each other by moving both multi-core fibers.

  The alignment in the X direction in the present embodiment is achieved by moving the end face 1b ′ of the multicore fiber 1 ′ to the position of the end face 1b of the multicore fiber 1 in S33. That is, the position in the X direction is arbitrarily determined depending on the position where the multi-core fiber 1 is held.

Note that the alignment is not limited to the case where the strength is maximized in each of the core C ′ ₂ and the core C ′ ₅ . For example, it is also possible to determine that the alignment has been completed when the average of the intensity of the light transmitted to the core C′2 and the core C′5 is maximized.

  In the present embodiment, the case where the light input to the multicore fiber 1 is transmitted to the multicore fiber 1 ′ has been described. However, the light input to the multicore fiber 1 ′ is transmitted to the multicore fiber 1, and the Y direction, Z It is also possible to align the direction and rotational direction.

[Action / Effect]
The operation and effect of this embodiment will be described.

  The coupling method according to the present embodiment is a method of coupling multi-core fibers in which a plurality of cores are covered with a clad. The bonding method includes a measurement process, an alignment process, and a fusion process. In the measurement step, light is input to the first core and the second core of the multicore fiber 1 and the intensity of the light transmitted to the first core and the second core of the multicore fiber 1 ′ is measured. In the alignment step, the multi-core fiber 1 and the multi-core fiber 1 ′ are moved relative to each other in the direction orthogonal to the long-axis direction and the rotation direction based on the light intensity measured in the measurement step. The multi-core fiber 1 and the multi-core fiber 1 ′ are aligned in the direction orthogonal to the rotation direction and the rotation direction. In the fusion process, after the alignment process is performed, the end face 1b of the multicore fiber 1 and the end face 1b 'of the multicore fiber 1' are fused.

  As described above, based on the light intensity measured in the measurement process, the multi-core fiber 1 and the multi-core fiber 1 ′ are aligned in the Y direction, the Z direction, and the rotation direction. In this case, alignment of the multi-core fibers in the Y direction, the Z direction, and the rotation direction can be reliably performed. Therefore, when coupling multi-core fibers, it is possible to suppress a decrease in coupling efficiency.

Further, in the present embodiment, at least one of the first core and the second core of the multi-core fiber 1 to which light is input in the measurement process is a core (for example, C ₂₎ disposed at a position closest to the outer periphery of the multi-core fiber 1. , C ₅ ).

  In this way, the amount of rotation can be increased by inputting light to the core disposed at the position closest to the outer periphery of the multi-core fiber and performing alignment in the rotation direction based on the light. Therefore, alignment becomes easy.

1, 1 ′ multi-core fiber 1b, 1b ′ end face 2 clad 2b, 2b ′ side face C _k core E _k end face

Claims (7)

A multi-core fiber coupling method for coupling multi-core fibers having a plurality of cores covered with a clad,
A first alignment step of aligning the one multicore fiber and the other multicore fiber in a direction perpendicular to the major axis by relatively moving one multicore fiber and the other multicore fiber When,
A first measurement step of inputting light to the first core of the one multi-core fiber and measuring the intensity of the light transmitted to the first core of the other multi-core fiber;
Based on the intensity of the light measured in the first measurement step, the one multicore fiber and the other multicore fiber are rotated relative to each other in the rotation direction, whereby the one multicore fiber in the rotation direction and the A second alignment step for performing alignment with the other multi-core fiber;
After the second alignment step is performed, a fusing step of fusing the end surface of the one multicore fiber and the end surface of the other multicore fiber;
A multi-core fiber coupling method comprising:   In the first alignment step, the one multi-core fiber and the other multi-core fiber and the other multi-core fiber are aligned in a direction orthogonal to the major axis direction of the multi-core fiber. The multi-core fiber according to claim 1, wherein the multi-core fiber is relatively moved to align the one multi-core fiber with the other multi-core fiber in a direction orthogonal to the long axis. Join method. The first alignment step includes
A second measuring step of inputting light to the second core of the one multi-core fiber and measuring the intensity of the light transmitted to the second core of the other multi-core fiber;
Based on the light intensity measured in the second measuring step, the one multi-core fiber and the other multi-core fiber are moved relative to each other in the direction perpendicular to the major axis direction, thereby orthogonal to the major axis direction. The multicore fiber coupling method according to claim 1, wherein the alignment of the one multicore fiber and the other multicore fiber in a direction to be performed is performed.   The multicore fiber coupling method according to claim 3, wherein the second core is a core disposed at a center of the multicore fiber.   5. The multicore fiber coupling method according to claim 1, wherein the first core is a core disposed at a position closest to an outer periphery of the multicore fiber. 6. A multi-core fiber coupling method for coupling multi-core fibers having a plurality of cores covered with a clad,
A measuring step of inputting light to the first core and the second core of one multi-core fiber and measuring the intensity of the light transmitted to the first core and the second core of the other multi-core fiber;
By moving the one multicore fiber and the other multicore fiber relative to the direction perpendicular to the major axis direction and the rotation direction based on the light intensity measured in the measurement step, the major axis direction An alignment step of aligning the one multicore fiber and the other multicore fiber in a direction orthogonal to the rotation direction and the other multicore fiber;
After the alignment step is performed, a fusion step of fusing the end surface of the one multicore fiber and the end surface of the other multicore fiber;
A multi-core fiber coupling method comprising:   The multicore fiber coupling method according to claim 6, wherein at least one of the first core and the second core is a core disposed at a position closest to an outer periphery of the multicore fiber.

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