| 摘要 |
PROBLEM TO BE SOLVED: To enable transmitting modulation signal light with less deterioration by changing the phase of the modulation signal light outputted from a Mach- Zehender interference device type (MZ type) light intensity modulator according to its intensity. SOLUTION: A chirp adding part 10 is provided on the output side of the MZ type light intensity modulator 83 as a light phase conversion means changing the phase of the modulation signal light (duo-binary signal light) outputted from the MZ type light intensity modulator 83 according to its intensity. The chirp adding part 10 is constituted of a light phase modulator 11, a delay adjustment circuit 12 inputting a binary data signal and imparting a prescribed delay and an amplitude adjustment circuit 13 adjusting its amplitude and driving the light phase modulator 11, and modulates the phase of the duo-binary signal light in proportion to the binary data. Then, the intensity of the modulation signal light for the central value of the amplitude of the duo-binary signal is minimum, and the phases of the modulation signal light for other binary are inverted to each other, and further, the phase of the modulation signal light is changed continuously according to its intensity. |
