| 摘要 |
PURPOSE:To obtain a fiber type phase shifter which has a small size and high performance and is simple in coupling system by using a single polarization fiber provided with a stress applying part having the coefft. of thermal expansion differing from that of a core as a phase shifter. CONSTITUTION:A stress applying part 2 is provided in addition to a core 1 and a clad 3 to a single polarization fiber. B2Os, etc. are added to the fiber and the fiber is cooled after drawing in order to make the coefft. of thermal expansion larger in the part 2' than in the clad 3; therefore, tensile stress is generated in the axial X direction in the core 1. The phase difference for the two polarization modes of the single polarization fiber can be made different by integer times of pi/2 by the double refraction occuring in the difference in stress in the core 1. Therefore, if such single polarization fiber is used, the fiber type phase shifter which has a small size and high performance and permits easy connection to an optical fiber is obtained. |
