JPH0827413B2 - Batch fusion splicing method for multi-core optical fibers - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a collective fusion splicing method for a multi-core optical fiber in which a plurality of optical fibers are arranged in parallel at intervals.

(Prior Art) Although many fusion splicing methods for multi-core optical fibers have been developed, Japanese Patent Laid-Open No. 59-118 is an example of a method generally used as a collective fusion splicing method.

As the multi-core optical fiber core wire, a 5-core flat type optical fiber core wire (1) as shown in FIG. 3 is presently standard, which will be described as an example. In the drawing, (2) shows an optical fiber, and (3) shows a coating.

In the case of collectively fusion-splicing such a multi-core optical fiber (2), first, the coating portion (3) at the end of the optical fiber core wire (1).
Is removed to expose the optical fiber (2), the ends thereof are cut and aligned, and then the optical fiber (2) is mounted on a fusion splicer.

The most important thing in this fusion splicing of multi-core optical fibers is that when the optical fiber core wire (1) is set in the fusion splicer and the connecting end faces of the optical fibers (2) are butted against each other, the axes of all five cores are aligned. That is correct. Regarding axis alignment, there are a vertical axis (X) and a horizontal axis (Y) of the circumferential axis, and further, there is a Z axis in the axial center direction. Of these, the vertical axis (X) and the horizontal axis (Y) show the optical fiber (2) in the V groove (4a) of the V groove base (4) provided in the fusion splicer as shown in FIG. The axis can be aligned by inserting it.

On the other hand, the alignment of the Z axis in the axial direction of the optical fiber (2) is performed by cutting the ends of the optical fiber (2). A special fiber cutter is used to trim the ends of the optical fibers (2).
There is a variation of 20 to 50 μm in the cut length of the optical fiber at the core, which causes misalignment (5) as shown in FIG.

The variation due to the cutting of the connecting end surface of the optical fiber (2) is caused by the size of the scratch given to the optical fiber (2) depending on the conditions such as the blade pressure of the fiber cutter, the shape and angle of the blade, and the degree of wear. In the stress rupture method, if the flaw applied to the optical fiber (2) is large, the fracture occurs with a small stress, and if the flaw is small, a large stress is required, and the stress causes the optical fiber (2) to cover the optical fiber core wire (1). The connection end face of the optical fiber (2) is uneven because it projects from the portion (3). Further, after cutting, the optical fiber core wire (1) is bent or extended even when it is mounted in the fusion splicer, so that the optical fiber (2) is projected or retracted and set in the fusion splicer. At this time, the variation (5 ') in the end face spacing (see FIG. 5) in the axially butted state of each of the five cores is further increased. Table 1 shows the amount of unevenness of the tip due to the cutting and handling of an optical fiber of a normal 5-fiber flat optical fiber, for each type of coating.

Since the fusion splicing cannot be performed in such an unaligned state, when the optical fiber core wire (1) is attached to the fusion splicer,
Random absorption measures are taken.

FIG. 6 is an explanatory view showing a state in which the optical fiber (2) is attached to the fusion splicer, and the cut optical fiber (2) is comb teeth (32), a comb tooth base (33), and a V groove base (34). ), And the coating portion (3) of the optical fiber core wire (1) is placed on a core wire fixing base (30) having a constant angle (θ) and the core wire clamp (31). The optical fiber (2) is also fixed to the V groove base (34) and the comb tooth base (33) by the soft clamp (36) and the hard clamp (37).

In this state, the vertical axis and the horizontal axis of the tip of the optical fiber (2) are aligned by being set in the V groove of the V groove base (34), but the axial direction is the cutting of the optical fiber (2). Also, the length of the tip is not uniform due to handling. Therefore, it is necessary to make the lengths of the tips uniform, and the core fixing base (30), the comb teeth (32), and the comb teeth base (33) are gradually advanced in the axial direction so that the shortest optical fiber (2) Push the optical fiber (2) until the end face hits the stopper (35).
Align the tips of.

When the tips of the optical fibers (2) of the five cores are aligned, the hard clamp (37) is mechanically strongly pressed and clamped so that the optical fibers (2) do not move. At this time, the five-core optical fiber (2) is based on the shortest optical fiber, and the four long optical fibers are the four optical fiber fixing bases (30) and the comb tooth bases (33).
Between them, as shown by the dotted line in FIG. 6, a state (2 ') is obtained by bending the difference in length.

After aligning the ends of the optical fibers (2) to be connected in this way, the stopper (35) is removed and the ends of the optical fibers (2) are fusion-spliced by butt discharge.

(Problems to be Solved) The above-mentioned method is a general fusion splicing method for multi-core optical fibers which is generally performed at present, but this method has the following problems.

That is, as described above, the comb tooth base (33) is provided in order to correct the unevenness of the connection end face due to the cutting and handling of the optical fiber (2) by the fusion splicer, and when the optical fiber (2) is mounted, the hard clamp ( Lightly press the optical fiber (2) with 37), and stop the optical fiber (2) with the stopper (3
Press the hard clamp (37) strongly after hitting (5) and aligning the connection end faces to give a long optical fiber a bend (2 '), but if the amount of misalignment is large, the optical fiber bends (2') will break. Occurs. At this time, even if there is no disconnection, if the connection is completed, the connection part is taken out from the fusion splicer, and the optical fiber is made linear, all the tension is applied to the shortest connected one of the five optical fibers. It often breaks.

To facilitate the correction of this misalignment, the cord fixing base (3
Although a certain angle (θ) is attached to 0), this means that bending stress that causes disconnection of the optical fiber (2) is given before connecting.

Also, the cut length of the optical fiber (2) to correct the misalignment (distance from the stripping of the coating to the end face of the optical fiber)
Is long (currently 20 mm), so the connection length is 40 mm on the left and right, and the length of the reinforcing part of the connection part is as large as 70 mm. On the other hand, the development of miniaturization of the connection reinforcing portion of the optical fiber is being advanced, and with the increase in the number of optical fiber cables, there is a strong demand that the length of the connection reinforcing portion is 50 mm or less. To reduce the length of the connection reinforcement part to 50 mm or less,
At present, a connection length of 40 mm cannot be realized in terms of strength and reliability, and there is a strong demand for a reduction in the length of the fusion splicing part.

(Structure of the Invention) The present invention performs collective fusion splicing without correcting the unevenness of the optical fiber tip, which is the above-mentioned problem, and further, collectively melts a multi-core optical fiber in which the splicing length is reduced to 1/2 of the conventional one. A method for connecting and disconnecting the optical fiber is provided by previously fixing the optical fiber core wire to a detachable fixing jig to remove the end coating portion of the optical fiber core wire to expose the optical fiber. The connection end faces of the optical fibers are cut and aligned, and then the fixing jig is attached and fixed to the core fixing base of the fusion splicer without removing the fixing jig, and then the multi-fiber optical fiber is mounted. It is characterized in that the core wire fixing base is slightly moved to butt the connection end faces thereof, and they are collectively fused and connected.

FIG. 2 shows a fixing jig used in the present invention. FIG. 2A is a top view, FIG. 2B is a vertical sectional view, and FIG. 2C is a sectional view taken along line XX in FIG. Is shown.

The fixing jig (10) is composed of a fixing base (18) and an upper lid (19). The fixing table (18) is provided with an insertion groove (20) for the optical fiber core wire (1) and a magnet (22) for adsorbing this when the upper lid (19) is closed in the lengthwise direction. After inserting the optical fiber core wire (1) into (20), the upper lid (19) is closed, and the optical fiber core wire (1) is fixed by attracting the upper lid (19) with a magnet (22).

The upper lid (19) is composed of at least two pieces, and has an inner surface provided with a lining material (19a) made of rubber or plastic having a large frictional resistance, and a fixing table (1
8) is exposed (21) and forms a fixing base for fixing with the core clamp (16) when the fixing jig (10) is mounted on the core fixing base (11) (first See figure). Top lid (1
9) is composed of two pieces so that when the optical fiber core wire (1) is inserted into the insertion groove (20) of the fixing base (18) and clamped, the optical fiber core wire (1) is pointed. This is because it is easy to attach the optical fiber core wire (1) to the fixing jig (10) by pressing it with one upper lid to clamp it, and then holding it and clamping the second piece. .

Furthermore, when clamping the optical fiber core wire (1) to the fixing jig (10), the pressing force of the upper lid (19) against the fixing base (18) is required to hold down about 2 kg in order to hold down the movement of the optical fiber. When taking out the optical fiber splicing part from the fusion splicer at the time of completion, the upper lid (19) of the fixing jig (10) is divided so that it can be easily opened with a finger force of about 1 kg. Is.

Further, as described above, the fixing jig (10) is attached to the core fixing base (11) of the fusion splicer, and the core clamp (16) is attached so that the optical fiber axis is not displaced until the fusion splicing is completed. This is to form a fixing portion (21) for fixing the above.

Fixing jig (10) for preventing the above-mentioned movement of the optical fiber
The characteristics of the fixing jig (10) are determined by its length and the pressing force, and the characteristics of the fixing jig (10) used are as shown in Table 2.

The above value is the maximum value of n (number of data) = 10, and the pressing force is a magnet system, and one side is about 800 g.

By using a fixing jig with a length of 100 mm, the unevenness of the optical fiber end face can be suppressed within 15 μm at the maximum, the optical fiber mounting part of the fusion splicer can be simplified, and the connection length is 20 mm It could be reduced to 1/2.
As a result, it was possible to achieve highly reliable reinforcement with a 50 mm reinforcing member without reducing the size of the connection reinforcing part while maintaining the conventional reinforcing characteristics.

FIG. 1 is an explanatory view of the fusion splicing method of the present invention. Fix the optical fiber core (1) to be connected as described above with the fixing jig (1
Clamp to 0) to remove the end coating (3) to expose the optical fiber (2) and obtain a 10 mm optical fiber connection (23). In this way, the optical fiber core wire (3) is fixed to the jig (10).
The fixing jig (10) is placed on the core fixing base (11) of the fusion splicer with the optical fiber splicing part (23).
Is inserted into the V groove of the V groove base (13). Fixing jig (10) with the core clamp (16) and the connecting part clamp (15) while the optical fiber connecting part (23) is comfortably housed in the V groove.
Also, the optical fiber connection section (23) is pressed and fixed.

Thereafter, the optical fiber feed knob (17) is turned to feed the core fixing base (11) in the axial direction, and the optical fibers (2) are brought into contact with the fiber abutting plate (14). Make a slight movement. At this time, the optical fiber connection part (23)
Is clamped by the V-groove base (13) and the connection clamp (15), but the connection clamp (15) is adjusted to be lightly clamped, so the optical fiber connection (23) slips between them. And proceed.

After confirming the mutual axial alignment and spacing of the optical fibers (2) with the fiber abutting plate (14), the fiber abutting plate (14) is lowered to generate arc discharge and fuse the end faces of the optical fibers. At this time, the optical fiber (2) on one side is moved by the thickness (20 to 30 μm) of the fiber abutting plate (14) to the other side and spliced.

(Effects of the Invention) According to the above-described method for collectively splicing multi-core optical fibers of the present invention, the splicing part having the following advantages and having a reduced splicing length can be obtained.

By using a fixing jig, it is possible to obtain a connection end in which the end faces of the optical fibers are aligned to the extent that they can be absorbed in fusion splicing, and it is unnecessary to correct the misalignment of the end faces of the optical fibers. No parts are required, and the connection mechanism is simplified and the connection operation is facilitated.

Conventionally, attachment of an optical fiber to a fusion splicer was carried out on the basis of three points of a comb tooth, a comb tooth base, and a V groove, and it was difficult to align the axes. However, in the method of the present invention, the axis alignment is achieved only by the V groove. Done,
It becomes easy to mount the optical fiber.

Since the comb teeth and the comb tooth base are not required, disconnection is reduced and the optical fiber's cabling length is shortened, and the connection length can be reduced from 40 mm to 20 mm.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of a method for collectively fusion splicing multi-core optical fibers of the present invention, and FIG. 2 is a top view (FIG. 2A) and a vertical cross-sectional view (same as FIG. 1) of a fixing jig used in the method of the present invention. B) and second
It is a sectional view taken along line XX in FIG. 3 is an explanatory view of a multi-core optical fiber core wire, FIG. 4 is an explanatory view of axis alignment of an optical fiber by a V groove, FIG. 5 is an explanatory view of unevenness of an end face of an optical fiber, and FIG. It is an explanatory view of a destination connection method. 1 ... multi-core optical fiber core wire, 2 ... optical fiber, 3 ...
Covering part, 10 …… Fixing jig, 11 …… Cable fixing base, 13 …… V
Groove, 14 …… Fiber abutment plate, 15 …… Clamp on connection part,
16 …… Core cable clamp, 18 …… Fixing stand, 19 …… Top lid, 20…
… Optical fiber core wire insertion groove.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yuichi Usui Yuichi Usui 1 Taya-cho, Totsuka-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Shuzo Suzuki, 1 Taya-cho, Totsuka-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industry Co., Ltd.Yokohama Works (72) Inventor Keiji Osaka 1 Taya-cho, Totsuka-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries Co., Ltd. Yokohama Works (72) Inventor Atsushi Ide Tokai-mura, Ibaraki Prefecture Address 162, Nippon Telegraph and Telephone Public Corporation, Ibaraki Electro-Communications Research Laboratories (56) Reference JP-A-57-118210 (JP, A) JP-A-55-42262 (JP, A) SAI 55-118209 (JP, U) )

Claims (2)

[Claims] 1. In a method of abutting and fusing each optical fiber end face of a multi-core optical fiber core wire arranged opposite to each other, the optical fiber core wire is previously attached and fixed to a detachable fixing jig. In this state, the end coating portion of the optical fiber core wire is removed to expose the optical fiber, and then the connection end face of the optical fiber is cut and aligned, after which the fusion splicer is removed without removing the fixing jig. Attaching and fixing the fixing jig to the core fixing base to mount the multi-core optical fiber core,
After that, the core fixing base is slightly moved to bring the connection end faces into contact with each other, and the fusion splicing is collectively performed. 2. A fixing jig is composed of a fixing base having an insertion groove for an optical fiber core wire in a length direction, and a plurality of upper lids having an inner surface provided with a lining material made of rubber or plastic having a large friction resistance, 2. The method for fusion splicing of multi-core optical fibers according to claim 1, wherein the optical fiber cores are fixed by fixing the upper lid and the fixing base with a magnet.