| 摘要 |
PROBLEM TO BE SOLVED: To provide a polarization maintaining optical fiber coupler that is comparatively short in the optical coupling length, small in the inserting loss, and small in the fluctuation of a branching ratio over a wide range of wavelength, and also to provide the manufacturing method. SOLUTION: Assuming that the X direction is the one connecting each center of a stress imparting part of two polarization maintaining fibers (fibers) and that the Y direction is the one crossing the X direction at right angles, the polarization maintaining optical fiber coupler is such that the diameter in the Y direction of one panda-type fiber, in the cross section of the fusion part, is made smaller than that of the other fiber; such that the fibers are fused and drawn after brought into contact so that the X direction of each fiber is made nearly parallel to each other and that the direction connecting the center of both fiber cores roughly coincides with the Y direction; and such that the branching ratio in a prescribed wavelength region is almost flat in the wavelength characteristics. |
