| 摘要 |
PURPOSE:To prevent twisting and bending by constituting a heating section of a resistance heating element having the shape enclosing plural pieces of optical fibers over the entire circumference thereof. CONSTITUTION:The resistance heating element 5 is disposed to the central part of a hermetic vessel 4 and the optical fibers 1, 1 are positioned near the approximate central axis thereof. Further, two units of optical fiber fixing bases 6, 6 are disposed to both sides of the resistance heating element 5 in the hermetic vessel 4. The optical fibers 1, 1 are stretched by gliding the fixing bases on stretching supports 7, 7 in the direction where the spacing between the fibers is widened. The optical fibers 1, 1 are heated and welded from the entire circumferential direction to obtain the optical fiber coupler 3. Generation of the twisting and bending during the welding and stretching is thereby obviated. |
