JPS6355505A - Method for aligning multicore optical fiber - Google Patents

Abstract

PURPOSE:To facilitate aligning multicore optical fibers and to reduce the connection loss by making the light incident on all cores of the multicore optical fiber simultaneously and collectively receiving and detecting light outputs to align multicore optical fibers. CONSTITUTION:Single core optical fibers having 200mum core diameter which can make the light incident simultaneously on all cores of multicore optical fibers 11 and 12 and simultaneously receive light outputs from all cores are used as an optical fiber 13 for incidence and an optical fiber 14 for light reception. The optical fiber 13 for incidence having 200mum core diameter and the multicore optical fiber 11 are butted, and the light is made incident simultaneously on all cores of the multicore optical fiber 11 from a light source 4, and an inching stage 8 is so controlled that light outputs are collectively and simultaneously received by the optical fiber 14 for light reception having 200mum core diameter, and the multicore optical fiber 12 and the optical fiber 14 for light reception are butted. The light output from the optical fiber 14 for light reception is detected by a light receiving and detecting means consisting of a photodetector 5 and a power meter 6, and multicore optical fibers are aligned by a fusion splicing machine 9 so that the light output is maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for aligning a multi-core optical fiber having a plurality of cores in a single optical fiber cross section.

[Conventional technology]

FIG. 4 shows an example of the structure of a multi-core optical fiber.

1 indicates a multi-optical fiber, and 21 to 24 each indicate a core. When connecting multi-core optical fibers developed for communication, the cores 21 to 24 of the multi-core optical fibers to be connected are aligned with each other, and the fibers are aligned vertically and horizontally to minimize optical transmission loss. , it is necessary to perform relative positioning in the axial and rotational directions.

The conventional method of mutually aligning multi-core optical fibers of this type involves inputting light into each of the cores 21 to 24, detecting the light output from each core of the multi-core optical fiber on the receiving side, and determining the maximum optical output. The method used is to adjust the axis alignment of each core so that

[Problem that the invention seeks to solve]

The alignment of a multi-core optical fiber involves a larger number of cores than that of a single-core optical fiber, and it is not easy to perform an alignment operation that minimizes the splice loss of each core. In the conventional method of mutually aligning multi-core optical fibers, as each core is aligned, the cores that have already been aligned will become misaligned, so it is difficult to align all the cores. ,
There is a problem in that each time a single axis alignment is performed, it is necessary to enter light into all cores and check the optical output, making the adjustment operation extremely difficult.

[Means for solving problems]

The present invention solves the conventional problems by simultaneously inputting light into all cores of a multi-core optical fiber, detecting the optical output of all cores of the multi-core optical fiber on the receiving side at once, and aligning the optical fibers. , the end surfaces of the first and second multi-core optical fibers to be aligned with each other are made to face each other, and between the first multi-core optical fiber on the light transmitting side and the light source, and between the second multi-core optical fiber on the light receiving side and the light reception detection means. A single-core input optical fiber and light-receiving optical fiber that include all cores of each of the first and second multi-core optical fibers are interposed between them, and all of the first multi-core optical fibers are passed through the input optical fiber. simultaneously transmitting light to the cores of the second multi-excluded core optical fiber, simultaneously receiving the light output from all the cores of the second multi-excluded core optical fiber through the core of the light receiving optical fiber, and emitting it to the light reception detection means. It is.

[For production]

Since the present invention is a method of adjusting the relative positions of multi-core optical fibers in the vertical direction, horizontal direction, axial direction and rotational direction so as to maximize the optical output from the light receiving optical fiber to be detected, The alignment is completed by repeating the alignment, and furthermore, it is possible to eliminate the optical transmission loss due to incomplete alignment that occurs in the conventional alignment method in which light is incident on each core. Examples will be described below based on the drawings.

〔Example〕

FIG. 1 is a diagram illustrating an embodiment of the alignment method of the present invention. 11 and 12 are multi-core optical fibers on the transmitting side and receiving side, respectively; 13 and 14 are single-core input optical fibers having large diameter cores 15 and 16 that include all the cores of the multi-core optical fibers 11 and 12, respectively; A light-receiving optical fiber, 4 a light source, 5 a light-receiving element, and 6 a power meter.

Note that x, y, z, and θ coordinates are displayed in the horizontal, vertical, and
This indicates the direction of movement in the axial direction and the rotational direction. For example, by assembling an axial alignment system by fixing a fine movement stage (not shown) that can be moved in each of these directions to the multi-core optical fiber 11 or 12, the axial alignment system can be adjusted. The state of axis alignment can be detected by assembling.

As the light source 4, light obtained from, for example, an LED is incident on a single-core multimode optical fiber having a large diameter core 15 that covers all the cores of the multicore optical fiber 11, that is, blocks all the cores. The light enters the multi-core optical fiber 13 and simultaneously enters all the cores of the multi-core optical fiber 11. The input optical fiber 13 is connected to the light source 4 using, for example, an optical connector.

When the input optical fiber 13 with a large core diameter and the multi-core optical fiber 11 have the same cladding diameter, they are connected by a groove connection or the like. Even when the cladding diameters are different, since the core diameter of the input optical fiber 13 is large, the connection can be easily made even in a space connection. On the other hand, for the multi-core optical fiber 12 whose axis is to be aligned, all of the multi-core optical fibers 12 that are the same as the input optical fiber 13 are connected so that the output end side can receive the optical output from all the cores at once. A single light-receiving optical fiber 14 having a large-diameter core 16 that covers all the cores is connected, and the light output from the light-receiving optical fiber 14 is transmitted to, for example, the light-receiving element 5 and the power meter 6. Detection is performed by a light reception detection means consisting of: Axis alignment is performed by moving a fine movement stage (not shown), which is fixed to the multi-core optical fiber 11 or 12, in the horizontal, vertical, axial, and rotational directions so that the detected optical output is maximized. , adjust the relative positions of the multi-core optical fibers 11 and 12, and align their axes. In this alignment method, alignment is completed by -° alignment. Therefore, compared to the conventional method of injecting light into each core of a multi-core optical fiber for alignment, only one alignment operation is required, and the conventional method of injecting light into each core is less likely to occur. Incidentally, optical transmission loss due to incomplete alignment can be eliminated.

An example in which the alignment method of the present invention is applied to fusion splicing, which is one of the optical fiber splicing methods, is shown below along with a comparative example of fusion splicing using the conventional multi-core optical fiber alignment method. Shown below.

FIG. 2 shows a cross-sectional view of a multi-core optical fiber used for fusion splicing, l is a multi-core optical fiber, and 21 to 24 are cores.

FIG. 3 is a diagram showing an outline of an experimental system for aligning the axes of multi-core optical fibers. The same reference numerals as in FIG. 1 indicate the same parts, 7 and 8 are fine movement stages, and 9 is a fusion splicer.

Comparative example: By conventional method.

The multi-core optical fiber used had four cores, each with a core diameter of 30 μmφ. As the light source 4, L P and D having a wavelength of 1.3 μm were used. The fusion splice a9 used has the function of adjusting the relative positions of the multicore optical fibers 11 and 12 in the vertical, horizontal, axial, and rotational directions. 7 and 8 are fine movement stages. Further, in the conventional method, single-core optical fibers having a core diameter of 30 μmφ, which is the same as the core diameter of each of the multi-optical fibers 11 and 12, were used as the input optical fiber 13 and the light-receiving optical fiber 14.

First, in order to input light into one core of the multi-core optical fiber 11, the multi-core optical fiber 11 and the input optical fiber 13 are butted together, and the light-receiving optical fiber 14 is connected at the light-receiving end side.
The fine movement stage 8 is adjusted to move vertically and horizontally, and the light-receiving optical fiber 14 is fixed at a position where the light output is maximum. Then, the fine movement stage 7 is adjusted to move the position of the input optical fiber 13 at the input end in the vertical and horizontal directions, and the position of the input optical fiber 13 is fixed at a position where the maximum optical output can be obtained. After performing such operations, the shafts were aligned by the shaft alignment mechanism 9 before and after the fusion splicing.

While performing this mutual alignment of the cores for all the cores, the optical output of each core was checked and fusion splicing was performed. The time required for axis alignment was approximately 45 minutes.

The conditions for fusion splicing were: electrode spacing 1550 μm, indentation 13
0 μm, preliminary discharge 0.5 seconds, main discharge 3 seconds, discharge current 0.
2A, and the experiment was conducted 10 times. Table 1 shows the average splice loss before and after fusion splicing of each core in this experiment.

Example: According to the method of the invention.

The same multi-core optical fibers as in the comparative example were used, each having a core diameter of 30 μmφ. Light source 4, fusion splicer 9
, fusion splicing conditions, etc. are all the same as in the experiment in the comparative example.

The input optical fiber 13 and the light receiving optical fiber 14 are
For both multi-core optical fibers 11 and 12, single-core optical fibers with a core diameter of 200 μmφ were used that could simultaneously receive light incident on all cores and light output from all cores.

First, the input optical fiber 13 with a core diameter of 200 μmφ and the multi-core optical fiber 11 are matched, and the fine movement stage 7 is adjusted to input light from the light source 4 to all the cores of the multi-core optical fiber 11. 200μmφ
The fine movement stage 8 is adjusted so that the light output can be received all at once by the light receiving optical fiber 14, and the multi-core optical fiber 12 and the light receiving optical fiber 14 are butted, and the light output from the light receiving optical fiber 14 is transferred to the light receiving element. 5 and a power meter 6, and a fusion splicer 9 aligned the axes so that the light output was maximized, and performed fusion splicing. In this example, the time required for alignment is approximately 5 minutes. Connections before and after fusion splicing of each core in this case
The average values of loss are shown in Table 2.

Table 1 (Conventional) Table 2 (Invention) As is clear from Tables 1 and 2, according to the multi-core optical fiber alignment method of the invention, splice loss can be kept low. In addition, while the conventional method required about 45 minutes for the damping time for axis alignment, according to the present invention, it can be carried out in about 5 minutes. In this embodiment, an example was explained in which the input optical fiber 13 and the light receiving optical fiber 14 with large core diameters were used for simultaneous light input to a multi-core optical fiber and for receiving light output, but the same function can also be achieved by using a lens. This is one aspect of the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, by simultaneously inputting light into all cores of a multi-core optical fiber, receiving and detecting the optical output collectively, and performing axis alignment,
The alignment operation is easy and the splice loss can be kept small, making it highly effective when applied to measurement fields that require fusion splicing and alignment.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the present invention, Fig. 2 is a cross-sectional view of a multi-core optical fiber when the present invention is applied to fusion splicing, Fig. 3 is an experimental system for performing an alignment method for multi-core optical fibers, and Fig. Figure 4 shows an example of a multi-core structure. 1.11.12...Multi-core optical fiber, 4...
Light source, 5... Light receiving element, 6... Power meter, 7.8
...Fine movement stage, 9...Fusion splicer, 13...
Optical fiber for incidence, 14... Optical fiber for light reception, 1
4.16...Large diameter core, 21-24...Core

Claims (4)

[Claims] (1) In the method for aligning multi-core optical fibers, the end surfaces of a first multi-core optical fiber and a second multi-core optical fiber to be aligned with each other are faced to each other, and all the cores of the first multi-core optical fiber on the light transmission side are simultaneously transmitting light from a light source, receiving the light with the second multi-core optical fiber on the light receiving side, detecting the light receiving output of the second multi-core optical fiber at once, and detecting the light output of the first and second multi-core optical fibers at once. The opposed end surfaces are relatively moved in the circumferential direction, or in orthogonal directions between the horizontal and vertical directions, or in each of the above directions, so that the optical output transmitted from the light source through the first and second multi-core optical fibers is adjusted. A multi-core optical fiber alignment method characterized by alignment at the maximum position. (2) The method of simultaneously transmitting light from a light source to all the cores of the first multi-core optical fiber is such that the core diameter of all the cores of the first multi-core optical fiber is A single optical input fiber containing a core of the first multi-core optical fiber is interposed, and light is simultaneously transmitted to all the cores of the first multi-core optical fiber through the core of the input optical fiber. A method for aligning a multi-core optical fiber according to scope 1. (3) A method for simultaneously transmitting light from a light source to all cores of the first multi-core optical fiber includes
Claim 1, characterized in that a lens is interposed between the first multi-core optical fibers, and the light from the light source is diffused and transmitted from the lens to all the cores of the first multi-core optical fiber. The alignment method for multi-core optical fibers described. (4) A method for collectively detecting the optical output of the second multi-core optical fiber includes a single core that includes all the cores of the second multi-core optical fiber and is located opposite to the output end face of the second multi-core optical fiber. A patent characterized in that a light-receiving optical fiber is arranged, and the light output from all the cores of the second multi-core optical fiber is simultaneously received through the core of the light-receiving optical fiber and emitted to a light reception detection means. A method for aligning a multi-core optical fiber according to claim 1.