| 摘要 |
PROBLEM TO BE SOLVED: To constitute a switch device, etc., by varying the dielectric constant in an optical fiber which is equipped with an input, an output, and an intermediate part and doped with a rare earth element by variation of the magnetism of a magnet provided at the intermediate part of the optical fiber, and varying the state of light passing through the optical fiber. SOLUTION: In the switch device 1, the polymer optical fiber 13 doped with erbium, etc., guides an input light signalλi from the input part 2. A phase detector 16 outputs a phase difference (λi-λo) signal 16a generated by comparing the input light signalλi of an optical demultiplexer 11 provided at the input end of the optical fiber 13 with the output light signalλo of an optical demultiplexer at the output terminal. Then when a switch 15 is turned on and the electromagnet 14 provided at the intermediate part of the optical fiber 13 is excited and moved while a magnetic field is applied to the optical fiber 13, the dielectric constant in the optical fiber 13 varies to cause the passing light in the optical fiber 13 to vary. The variation is detected by the phase detector 16 to detect the movement of the electromagnet 14.
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