| 摘要 |
PURPOSE:To realize a low distortion transmission by making a distortion characteristics of a photodetector used for an photoelectric negative feedback loop driving a light emitting element at the sending side nearly equal to the distortion characteristic of a photodetector used at the reception side. CONSTITUTION:An optical attenuator 10 attenuates the light power inputted to an APD 11 so as to be equal to the received light power of the APD at the reception side. Further, the multiplication factor M of the ADP 11 is selected the same as that of the APD at the reception side. The APD 11 has the same distortion characteristic as that of the APD at the reception side. The optical output inputted from an LD 1 to an optical fiber 4 is an output compensating the distortion characteristic of the LD 1 and the APD 11 when the distortion of amplifiers 9, 3 is sufficiently small. When the output light is received by an APD 13 having the same distortion characteristic as that of the APD 11, the distortion of the APD 13 is cancelled. |
