| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical transmitter/receiver which attenuates optical power of an output light of an optical transmission part to a sufficiently low level without stopping a function of an optical reception part, and a control method therefor.SOLUTION: The optical transmitter/receiver comprises: a light source; a DP-QPSK (polarization multiplexed quaternary phase modulation) modulator 5 including slave modulators 41 and 42 to which CW light is inputted from the light source, a master modulator 44 to which output light from the slave modulators are inputted, and an optical power monitor 11 to which inverted output of transmission light from the master modulator is inputted; a bias control circuit 7a that applies a bias voltage; a drive signal generation circuit 7b that applies a drive signal to the slave modulator; and an optical reception part that utilizes the CW light inputted from the light source to convert reception light from the outside into an electric signal. When shielding the transmission light, the drive signal generation circuit stops the drive signal and the bias control circuit changes the bias voltage in such a manner that a phase difference between light beams passing the slave modulators becomes zero and that a phase difference between output light beams passing the master modulator becomes π.SELECTED DRAWING: Figure 2 |
