| 摘要 |
The present invention provides an optical switch in which a switching operation is not affected even when the polarization state of a control light varies. The optical switch comprises a loop-form optical waveguide loop circuit formed from an optical nonlinear medium, control light input means of phase control means for inputting the control light into the optical waveguide loop circuit, a wavelength demultiplexing/multiplexing circuit, and a phase bias circuit. The optical waveguide loop circuit is constituted by an optical path formed from a first polarization-maintaining single-mode fiber extending from an optical demultiplexer/multiplexer to the control light input means, an optical path formed from a second polarization-maintaining single-mode fiber extending from the control light input means to the wavelength demultiplexing/multiplexing circuit, and an optical path formed from a fourth polarization-maintaining single-mode fiber extending from the wavelength demultiplexing/multiplexing circuit and returning to the optical demultiplexer/multiplexer. The wavelength demultiplexing/multiplexing circuit is formed as a loop-form optical waveguide loop circuit by a third polarization-maintaining single-mode fiber connecting a wavelength demultiplexer and a multiplexer, a fifth polarization-maintaining single-mode fiber connecting the wavelength demultiplexer and a polarization plane rotation portion, and a sixth polarization-maintaining single-mode fiber connecting the polarization plane rotation portion and the multiplexer. The phase bias circuit is inserted at a point on any one of the first through fourth polarization-maintaining single-mode fibers.
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