To reduce power consumption significantly when compared with the digital coherent system, by reproducing the local light emission stably and simply over a wide wavelength range.
The coherent receiver comprises: an optical amplifier 1 which amplifies the input signal light; an optical demultiplexer 2 which demultiplexes the signal light amplified by the optical amplifier 1 into two; a local emission reproducer 3 which reproduces the local emission from one signal light demultiplexed by the optical demultiplexer 2; an optical multiplexer 4 which multiplexes the other signal light demultiplexed by the optical demultiplexer 2 and the local emission output from the local emission reproducer 3; and an optical receiver 5 which performs photoelectric conversion of the light output from the optical multiplexer 4. The local emission reproducer 3 consists of an optical frequency multiplexer 6 which outputs the second harmonic having twice the frequency of one signal light demultiplexed by the optical demultiplexer 2, and an optical frequency divider 7 which outputs the local emission while dividing the frequency of the second harmonic by 2.
Shigeki Yamakawa
Yuzo Koike