| 摘要 |
PURPOSE:To reduce noise and to miniaturize an equipment by selecting the length of a short optical transmission line making it possible to constitute a resonator in a way that a time required for one round propagation of an optical signal is an odd number multiple of a half of the signal modulation period. CONSTITUTION:An optical signal is sent from an optical transmitter 1 provided with a semiconductor layer 1A via an optical cable forming a long optical transmission line 3. A photocoupler 4 of an optical receiver 2 detects a signal from the long optical transmission line 3 and a short transmission line 5 is provided between the photocoupler 4 and a photocoupler 4' provided on a photodetector 2A to receive the optical signal. The length L of the short transmission line 5 is selected so that the time of the optical signal requiring to propagate through the line 5 is an odd number of multiple of a half of the signal modulation period. Thus, the conversion of an optical phase noise into intensity noise is prevented, the communication equipment is miniaturized and manufactured at a low cost. |
