| 摘要 |
PURPOSE:To reduce the cost and to decrease the size of the device by using a module including a photodetector receiving a light from an optical fiber and a light from a light emitting element and applying two-way optical transmission through one optical fiber. CONSTITUTION:A signal from a modulation circuit 9 is converted into an optical signal by a light emitting element 2 and sent via an optical fiber 4. Moreover, part of the optical signal from the element 2 is made incident in the photodetector 3, where it is converted into an electric signal and fed back to an APC circuit 7 via an amplifier circuit 5 and a changeover switch 6. Since the circuit 7 is operated so that the optical output from the element 2 is made constant, the stable optical signal is supplied. Then the optical signal sent from the fiber 4 is made incident in the element 3, where the signal is converted into an electric signal and amplified by the circuit 5. Part of the output of the circuit 5 is fed back to the AGC circuit 8 and the gain of the circuit 5 is controlled, then the output of the circuit 5 is kept constant. The output is demodulated by a demodulation circuit 10. |
