| 摘要 |
PURPOSE:To extend the life of a semiconductor laser diode by sending information, which indicates that the reception level in an optical reception part is too high, to an optical transmission part and reducing the optical transmission level to control the optical reception level to a certain value. CONSTITUTION:The reception side detects the reception level of a received optical signal and sends back this detection signal to the transmission side, and this signal related to the optical reception level from the reception side is received through an input terminal 11 by a reception circuit 12 and is converted to a gain control signal VC for an amplifier 8 by a signal converting circuit 13. The gain of the amplifier 8 is controlled by this gain control signal VC, and the gain is reduced when the optical reception level on the reception side is high. Consequently, the optical output of a semiconductor laser diode 5 is controlled to prevent the optical reception level in the reception part from being too high. Thus, the reduction of the life of the semiconductor laser is avoided. |
