Bias system in an optical CATV modulator

摘要

An analog-external-modulation optical, emitter is described which comprises an electro-optical 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 electro-optical 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 electro-optical modulator through a band-stop filter adapted to eliminate the pilot tone downstream of the linearizer circuit.