| 摘要 |
PURPOSE:To obtain an optical star coupler which provides equal distribution while reducing excessive loss by providing plural optical fibers with a twisted small-diameter part, and making the taper ratio of optical fiber diameters on both sides of a small-diameter part nearly uniform. CONSTITUTION:Two optical fibers 1-1 and 1-2 are arranged in parallel and while the center parts are heated, the fibers 1-1 and 1-2 are drawn as shown by arrows 11-1 and 11-2 and also rotated as shown by arrows 17-1 and 17-2 to give a twist 12 to the drawn parts. The number of times of the twisting is set small when the drawing ratio is large or large when small. Then, while the twisted part 12 is heated by a heat source 10, the parallel fibers are drawn again as shown by arrows 13-1 and 13-2 and light is made incident on the end of one of the fibers so as to obtain equal distribution characteristics. Then, the heating and drawing treatments are carried out while light electric power emitted from the output terminal of the fiber on the opposite side is monitored so that it is almost equal. Then, the fused and drawn part 14 is sheathed with a protection tube 15, which is fixed to the fibers with an adhesive 16.
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