| 摘要 |
PURPOSE:To obtain a signal output of high S/N by using a high frequency signal as the voltage applied to a photoelectric conversion means. CONSTITUTION:An APD 4 is connected in series between a high frequency signal generator 12 and a resistance 3, and the reception optical signal having a carrier frequency f1 is inputted through an optical transmission line 1. A first high frequency signal having the carrier frequency f1 or a second high frequency signal having a frequency f2 is applied from a high frequency signal generator 12 to the APD 4. When the APD 4 is driven by the high frequency signal having the frequency f1 or f2, the reception optical signal is demodulated or is subjected to frequency conversion and a base band signal or an intermediate frequency signal having a frequency f0=¦f2-f1¦ is outputted from the APD 4. The base band signal or the intermediate frequency signal has a high S/N because it is not subjected to high frequency amplification. |
