| 摘要 |
PURPOSE:To stabilize the absolute wavelength which is a reference for a local oscillation light source and signal transmitting light source in a demand assignment type coherent light transmitting and receiving device and to facilitate the wavelength setting of these light sources. CONSTITUTION:A signal receiving circuit 1 stands by in the state of receiving a common signaling channel f11 in a non-communication state and the local oscillation light source 3 is nearly tuned with the frequency of this f11. The signal transmitting light source 4 is also stabilized by detecting a beat signal through a detecting circuit 18 so as to tune with the local oscillation light in the non-communication state. This detecting circuit 18 is constituted of a photodetector 11, an amplifier 12 and a frequency distriminator 13. |
