| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical amplifier with an optical output control function capable of performing a stable reflection detecting operation and transmitting a monitoring control signal. SOLUTION: Upon reception of an optical signal at an optical input terminal thereof, this optical amplifier amplifies an optical signal having a single wavelength or a plurality of wavelengths for transmitting information from the optical input terminal, and outputs light having a wavelength or a plurality of wavelengths different from that or those of the above optical signal. Optical coupling means 2 couples the output from the amplifier 1 to that from a light source 9. Optical branching means 3 not only couples an output from the means 2 to a transmission path but also extracts a reflected optical signal from the transmission path. Then, a wavelength component in the output from the source 9 is detected from part of the reflected light extracted by the means 3. A gain control circuit 5 controls the gain of the optical amplifier based on the detection result. A reflected light detecting circuit 4 decreases the gain of the circuit 5 when the detected reflected light output becomes a predetermined value or above. |
