OPTICAL TRANSMISSION CIRCUIT

摘要

PURPOSE: To minimize non-linear distortion owing a voltage-light output characteristic by inputting an output from a predistortion electric circuit to a semicoductor field absorption type optical modulator as a modulation signal. CONSTITUTION: The bias voltage of the semiconductor field absorption type optical modulator 18 is set up so as to minimize secondary distortion by the non-linearity of a voltage (V)-light output (L) characteristic of the modulator 18 based upon the V-L characteristic. A signal obtained by adding tertiary distortion generated by the modulation of the modulator 18 based upon a modulation signal and tertiary distortion with a reverse phase to the modulation signal to be inputted to the modulator 18 is inputted from the predistortion electric circuit 17 to the modulator 18 as a modulation signal. Thereby a secondary non-linear distortion can be minimized, tertiary distortion can be compensated by predistortion compensating method and an optical transmission circuit with low distortion can be obtained.