| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-way optical amplifier circuit having a function capable of surely detecting a reflected light from an open end at a low cost. SOLUTION: Photodiodes 44, 24 detect the power of a received light. When the power is a prescribed identification level or below, it is judged that not the received light but a reflected light at an open end of a transmission light at the opposite side is detected. Then the level of the output light of EDFs 32, 42 is decreased by decreasing the bias current of laser diodes 30, 50 at the opposite side. |
