| 摘要 |
PROBLEM TO BE SOLVED: To provide a wavelength converter reduced in loss and also improved in extinction ratio. SOLUTION: A polarizer 12 separates incident lightλ2 into X polarized light and Y polarized light intersecting each other at right angles. The incident lightλ2 is a linearly polarized wave. The X polarized light is made incident upon a polarizer 17 through a semiconductor light amplifier 16. The Y polarized light is led into the polarizer 17 by reflection devices 13, 14. The refractive index of a waveguide of the amplifier 16 is changed in accordance with the intensity of incident light. Signal lightλ1 of which intensity is modulated in accordance with a transmission signal is made incident upon the amplifier 16. The polarizer 17 multiplexes the X polarized light and the Y polarized light. A polarizer 18 receives and outputs the output light from the polarizer 17.
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