| 摘要 |
PROBLEM TO BE SOLVED: To simply detect the distorted state of a received optical pulse signal. SOLUTION: A post-transmission optical waveform 13 is controlled by an optical amplifier 2 so that output power is a constant level, converted into an electrical signal by O/E converter 3 and controlled by an amplifier circuit 4 so that power is a constant level, and a direct current component is eliminated by an AC coupler 5. Next, the slanted line part of an in-phase electricity waveform 14 is inputted to a lowpass filter 8 by an offset adjustment circuit 6 and a rectifier 7. Next, a voltage comparison circuit 9 compares a voltage circuit output 16 decided by a variable voltage circuit 11 with a filter output 15 of the filter 8, and it can be detected whether a pulse distortion is due to pulse compression or pulse expansion, in such a manner that a voltage monitor 10 monitors the comparison output. Adverse effects due to automatic dispersion compensation and nonlinear optics by feedbacking a value detected by the monitor 10 to a dispersion compensation module 17 and by controlling the gain of the optical signal. |
