Bias system in an optical CATV modulator

摘要

An analog-external-modulation optical emitter is described which comprises an electrooptical modulator and a piloting circuit. The piloting circuit comprises a pilot-tone-generating circuit; an electric control signal generated by the optical signal coming out of the modulator and a predetermined bias voltage are fed to the input of a differential amplifier the output of which is added to the pilot tone to feed an electric input of the electrooptical modulator. The RF input of the analog electric signal is connected to a linearizer circuit to which the pilot-tone-generating circuit is also connected. The output of the linearizer circuit is sent to an electric input of the electrooptical modulator through a band-stop filter adapted to eliminate the pilot tone downstream of the linearizer circuit.