| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a wavelength conversion circuit capable of canceling polarization dependency of variation in a refractive index remaining in a semiconductor optical amplifier. SOLUTION: An optical multiplexer/demultiplexer 121 branches CW light into halves. The semiconductor optical amplifiers 101, 102 amplify the branched CW light. Multiplexed output light by the semiconductor optical amplifiers 101, 102 is made to exit to output parts 151, 152 of an optical multiplexer/ demultiplexer 123. An optical multiplexer/demultiplexer 122 makes the light amplified by the semiconductor optical amplifier 101 exit to the optical multiplexer/demultiplexer 123, and also makes the signal light incident to the semiconductor optical amplifier 101. The signal light is superimposed on the wavelength of the CW light. The output light is propagated and made incident from/to the output part 151 to/from the output part 152 via looped optical waveguide composed of optical waveguides 161 162 and a half-wave plate 14. The half-wave plate 14 is arranged on the way of the looped waveguide, and rotates the plane of polarization of the passing light by about 90 degrees.</p> |
