| 摘要 |
PURPOSE:To provide a simple connecting method between a waveguide type optical element and incident and exit optical fibers for retaining plane of polarization by interposing single mode fibers of a specific length between the waveguide type optical element and the optical fibers for retaining plane of polarization. CONSTITUTION:Four incident single mode fibers 2 are connected on the end faces of the four incident light waveguides of a waveguide type optical switch 12, and four exit single mode fibers 10 are connected to the end faces of the four exit light waveguides. The respective fibers 2, 10 are linear, and the length Z thereof is maintained at Z<=0.20/DELTAbeta in order to transmit a light wave by using the fibers 2, 10 of which the difference in propagation constant with respect to optional two polarized waves intersecting orthogonally with each other is DELTAbeta radian/meter and maintaining the same at an extinction ratio -20dB. Thus, when the light wave of either mode of TM or TE is made incident to optical fibers 1 for retaining plane of polarization, the mode of either TM or TE is maintained when the light wave arrives at the incident end face of a 4X4 waveguide type optical switch. |
