| 摘要 |
<p>PURPOSE:To stabilize the emitting light power by making an amplification factor constant even if a polarized wave state is varied by controlling a current allowed to flow to a semiconductor optical amplifier so that a power ratio of an incident light and an emitting light of a semiconductor optical amplifier becomes constant in a feedback circuit. CONSTITUTION:An incident side branching part 2, an incident side photodiode 4, an emitting side branching part 3, and an emitting side photodiode 5 are integrated monolithically on one substrate 7 together with a semiconductor optical amplifier 1. In such a state, when an incident light which is made incident from an incident wave path 1a is amplified by the semiconductor optical amplifier 1 and emitted to an emitting waveguide 1b, a part of an incident light and an emitting light to the semiconductor optical amplifier 1 is allowed to branch in the respective branching parts 4, 5 and detected by photodiodes 4, 5, respectively, a power ratio of both the light is monitored in a feedback circuit 6, and also, the current supply to the semiconductor optical amplifier 1 is controlled so that its power ratio becomes constant. Accordingly, even if a polarized wave state is varied and the amplification factor is varied, it can be corrected.</p> |
