| 摘要 |
PURPOSE:To simplify the constitution of the titled device by extracting a local oscillation light and a transmission light from the same light source to improve the reliability. CONSTITUTION:The 1st and 2nd emitting lights 3 are extracted respectively from the cleavage face of both ends of a semiconductor laser 1. The irradiated light 2 is propagated through a short single mode fiber 4, then used as a local oscillating light 5 and the irradiated light is used as a modulated light for a transmission light 20. The irradiated light 2 as the local oscillation light is combined with a received light 6 adjusted to have the same polarized wave as that of the local oscillation light 5 at an optical synthesis circuit 7. On the other hand, the irradiated light 3 is made incident to an optical modulator 19, goes to a transmission light 20 subject to intensity modulation by a modulation signal 18 and made incident to the transmission single mode fiber 21. Further, a part of the output is led to a frequency discrimination circuit 24 from a preamplifier circuit 10, an oscillated frequency control circuit 25 controls the operating temperature and injection current of the semiconductor laser 1 so as to stabilize the oscillated frequency of the semiconductor laser 1. |
