| 摘要 |
PURPOSE:To reduce cost and power consumption by utilizing the nonlinearity of an APD(avalanche photo diode) and a PD(photodiode) being light receiving elements so as to apply frequency conversion to an optical signal into a prescribed frequency band. CONSTITUTION:A bias voltage is applied to a light receiving element 1 receiving an optical FDM signal in which optional n-channels of f1-fn are frequency- multiplexed on a frequency axis. Furthermore, an output of a local oscillator 3 oscillated at prescribed frequencies F1-Fn is inputted to the element 1 by a channel selection signal 6. A desired channel is frequency-converted to the frequency band fs through the nonlinearity of the element 1, and the result is outputted via a preamplifier circuit 2, a BPF 4, and a main amplifier circuit 5. The oscillated frequencies F1-Fn of the oscillator 3 are selected to be Fn=fs+ fn or Fn=fs-fn, where fs is the reception band. Furthermore, the reception band fs is selected to a low or a high frequency side depending on the arrangement of the signals f1-fn subjected to frequency multiplexing. |
