JP2784895B2 - Batch fusion splicing of multi-core optical fiber - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fusion splicing method for optical fibers, and more particularly, to a batch fusion splicing method for multi-core optical fibers. 2. Description of the Related Art In a fusion splicing method for optical fibers, the ends of two optical fibers to be connected to each other are heated and melted together, and when they are pushed together in a direction in which they are joined, they are fusion spliced. In such a fusion splicing method, it is important to know exactly how much heat was actually applied. [0003] In particular, when multi-core optical fibers are connected collectively, it is important to uniformly heat these many optical fibers in order to perform reliable connection and reduce connection loss. It is desirable to measure uniformity accurately. Therefore, conventionally, for example, when atmospheric pressure discharge is used as a heat source, light generated by the discharge during the discharge is transmitted to a TV.
Attempts have been made to measure the heating intensity from the luminance distribution by taking an image with a camera or the like. [0005] However, in the method of measuring the heating intensity from the luminance distribution by imaging the light due to the discharge with a TV camera or the like, the amount of heat actually applied to the optical fiber is determined. It is not a direct measurement, but merely an analogy of this from the heat of the heat source itself as seen from the luminance, and it can be said that it is indirect and qualitative. Therefore, it is not possible to ensure the uniformity of heating during the fusion splicing of the multi-core optical fiber. Further, in order to analyze the brightness distribution from an image of discharge light captured by a TV camera or the like, a storage device or an image processing device for storing an image for one screen is required, and the entire device becomes large. There is a problem that it takes time. According to the present invention, when multi-fiber optical fibers are fusion spliced together, it is ensured that these many optical fibers are uniformly heated, so that all of the many optical fibers can be reliably and loss-free. It is an object of the present invention to provide a batch fusion splicing method of a multi-core optical fiber, which allows a batch connection with less trouble. In order to achieve the above-mentioned object, in the batch fusion splicing method of a multi-core optical fiber according to the present invention, the multi-core optical fiber is retracted by heating the tip of each optical fiber. After adjusting the heat source so that the amount is equal ,
Each of these optical fibers is heated and melted at a time, and the tip of each optical fiber of both multi-core optical fibers to be connected to each other,
It is characterized in that they are pushed together in the direction in which they abut each other and are fused. When heat is applied to the end of the optical fiber, the end is melted and rounded due to surface tension. Therefore, the tip position is retracted from the original position before heating by the amount of the roundness. Since the amount of retreat corresponds to the amount of melting at the tip, that is, the amount of heat actually applied to the tip, the heat source is adjusted so that the amount of retreat is equal.
If the tips of the plurality of optical fibers are heated collectively, the amounts of heat actually applied to the plurality of optical fibers can be accurately and quantitatively matched. [0011] Therefore, by integrally connecting the plurality of optical fibers so that the amounts of retreat due to the heating of the tips of the plurality of optical fibers are equal, uniform heating can be performed on all of the plurality of optical fibers and uniform melting can be performed. Thus, a plurality of optical fibers can be fusion-spliced together reliably and with low loss. In FIG. 1, a multi-core optical fiber 1 is formed in a tape shape, and each core is arranged in parallel. The coating 15 is peeled off at the ends, and the bare optical fibers 11 to 11 are removed.
14 is exposed. The bare optical fibers 11 to 14 are cut to have the same length, and the ends of each of them are aligned in a straight line. In this embodiment, in the fusion splicing device for multi-core optical fibers, the ends of the bare optical fibers 11 to 14 are heated collectively by atmospheric pressure discharge using a pair of electrodes 2 and 2. Although not shown in the figure, a multi-core optical fiber similar to the multi-core optical fiber 1 is placed on the lower left side of FIG.
It is arranged to face 1-14. The plurality of bare optical fibers of the omitted multi-core optical fiber are also cut to the same length, and the ends of each of the bare optical fibers are aligned. In this manner, the two rows of the plurality of bare optical fibers are collectively heated by the atmospheric pressure discharge by the electrodes 2 and 2 in a state where the ends thereof face each other. When actually heated, the ends of the bare optical fibers 11 to 14 are melted by the heat and deformed into a round shape as shown in FIG. 2 by the action of surface tension. Then, the tip position is retracted from the tip position indicated by the original dotted line by the amount of the deformation into the round shape. This retreat distance d1,
d2, d3 and d4 are respectively measured. Then, the larger the amount of heat actually applied to the tip of each of the bare optical fibers 11 to 14, the greater the amount of fusion, and therefore the greater the amount of retreat, so that the retreat distances d 1, d 2, d 3, and d 4 are equal to the respective optical fiber bare wires. It is considered that this corresponds to the amount of heat actually applied to the tips of 11 to 14. Therefore, the retreat distances d1, d2, d
If d3 and d4 are equal, the amounts of heat actually applied to the ends of the bare optical fibers 11 to 14 are equal. Therefore,
When a plurality of bare optical fibers 11 to 14 are collectively heated, the fusion splicing device is adjusted so that the retreat distances d1, d2, d3, and d4 of their tips become equal. The adjustment to make the retreat distances equal in this manner is performed not only for one row of bare optical fibers of one-side multi-core optical fiber to be fusion-spliced, but also for one row of multi-core optical fiber on the other side. This is also performed for bare optical fibers. The retreat distances d1, d2, d of this tip position
3, d4 can be visually observed using a microscope and measured by visual field scale, or measured on a monitor screen using a small TV camera and a monitor device,
Furthermore, it is also possible to process the tip image captured by the TV camera by the image processing device and automatically measure it. Even in the case of automatic measurement by processing with an image processing device, it is not necessary to store the information of the entire screen simply by measuring the moving distance of the tip positions of the bare optical fibers 11 to 14, so that the device can be easily configured. The size can be reduced and the processing time is not required. As described above, the retreat distance d from the position before heating after heating the distal ends of the bare optical fibers 11 to 14 is obtained.
Measuring 1, d2, d3, and d4 means measuring a quantitative parameter well corresponding to the amount of heat actually applied to the ends of the bare optical fibers 11 to 14. The coincidence of the retreat distances d1, d2, d3, and d4 means that
This indicates that the amounts of heat applied to the tips of the bare optical fibers 11 to 14 are the same. Therefore, if the fusion splicing apparatus is adjusted and fusion spliced as described above, a plurality of bare optical fibers are heated and melted by applying the same amount of heat, but these opposed ones are butted together. The optical fibers 1 can be pushed together in one direction to be connected collectively, so that reliable and low-loss collective fusion splicing of the multi-core optical fibers 1 can be performed. In the above embodiment, atmospheric pressure discharge was used as a heat source. However, the measurement method of the present invention can be applied to any device such as an oxyhydrogen flame or a carbon dioxide gas laser. As described above, according to the batch fusion splicing method of the multi-core optical fibers according to the present invention, the retreating amounts of the respective optical fibers due to the heating are equalized. Since the tips are heated collectively, they are pushed in the direction of abutment to perform the fusion splicing, so that all of the multiple optical fibers can be uniformly heated and melted evenly. The fibers can be fusion-spliced together reliably and with low loss. In order to perform uniform heating for all of the plurality of optical fibers, it is only necessary to measure the amount of retreat due to heating of each of the optical fibers. Therefore, it is very simple and can be easily performed even at a work site.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an embodiment of the present invention. FIG. 2 is a schematic diagram showing a shape change before and after heating an optical fiber tip. [Description of Signs] 1 Multi-core optical fiber 11 to 14 Optical fiber bare wire 15 Coating 2 Discharge electrode

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Go Yamada               Fuji Co., Ltd., 1440, Rokuzaki, Sakura City, Chiba Prefecture               Kura Sakura Factory                (56) References JP-A-61-256306 (JP, A)

Claims (1)

(57) [Claims] After adjusting the heat source so that the amount of retreat of the tip of each optical fiber of the multi-core optical fiber due to heating becomes equal , these optical fibers are heated and melted at a time, and both multi-core optical fibers to be connected to each other are melted. A fusion splicing method for multi-core optical fibers, wherein the tips of the optical fibers are pushed in a lump in a direction in which they abut each other and fusion spliced.