Optical transmission method and optical transmission apparatus

An optical transmission apparatus, comprising:

• an equalizing amplification circuit including a front end amplifier for amplifying a transmission signal obtained by photoelectric conversion, a differentiation circuit for producing a differentiation equalization signal from an output signal of said front end amplifier, and a variable gain amplifier and a post amplifier for amplifying an output signal of said differentiation circuit;
• a peak value detection circuit for detecting a peak value of said equalizing amplification circuit and outputting a dc voltage corresponding to the peak value;
• a dc amplifier for differentially amplifying the de voltage from said peak value detection circuit to control a gain of said variable gain amplifier;
• a dc regeneration circuit including a logic circuit for outputting a logically positive signal and a logically negative signal of the output signal of said equalizing amplification circuit and a set-reset tip-flop circuit for receiving the logically positive signal of said logic circuit as a set signal and receiving the logically negative signal of said logic circuit as a reset signal;
• a timing extraction circuit including a full-wave rectification circuit for full-wave rectifying the output signal of said equalizing amplification circuit, a timing extraction filter for extracting a timing signal from an output of said full-wave rectification circuit, and a narrow-band amplifier and a limiter amplifier for amplifying the timing signal;
• and
• an identification circuit for waveform shaping an output signal of said dc regeneration circuit using the timing signal from said timing extraction circuit.