| 摘要 |
PURPOSE:To increase an optical power to be sent with an ancillary signal and to make a reception signal level stable with the ancillary transmission signal by modulating an optical frequency of a light source with the ancillary signal and modulating and outputting the modulated output light with a main signal. CONSTITUTION:An optical modulator converts an output light of a light source 11 into an electric signal, and the output light of the light source obtained by controlling into a constant value with the electric signal is modulated by a main signal with an external modulator 13 and the modulated light is outputted. A terminal used to impress an ancillary signal is provided to an optical output control circuit 12 of the optical modulator, the output power of the light source is modulated by the ancillary signal, the output light modulated by the ancillary signal is modulated by the main signal in the external modulator 13 and the modulated signal is outputted. Through the constitution above, the ancillary signal to increase the optical power to be sent through an optical fiber is sent and the reception level is made stable by the ancillary signal. |
