| 摘要 |
PURPOSE:To provide the optical amplifier for enabling the control of a gain even when light for the control of an amplified gain is interrupted among optical signals to which the light of plural different wavelengths is multiplexed. CONSTITUTION:The optical signal amplified by an amplifier 12 is branched by an optical brancher 13 and inputted to an optical band pass filter 15. The light passed through the optical band pass filter 15 is converted to a voltage signal by a photoelectric transducer 16, and that peak value is detected by a peak detection circuit 21. This peak value is compared with a voltage value outputted from a reference voltage source 17 by a comparator circuit 18, the compared result is inputted to a laser diode driving circuit 19, and the amplified gain of the optical amplifier 12 is controlled. When it is detected by a light interruption detection circuit 23 that the light for gain control is interrupted, a holding circuit 22 holds the output of the comparator circuit 18 at a value just before the interruption of light is detected, and a filter control circuit 24 changes the passing wavelength of the optical band pass filter 15 into the wavelength of a different optical signal. When the light of the other wavelength is detected by the peak detection circuit 21, holding due to the holding circuit 22 is canceled. |
