Emcore Corporation

Emcore Coporation

John Caton

Daniel McGlynn

Gustav Witzel

John Klima

Joseph Hober

A data communications network in which a first information-containing radio frequency signal input is applied to a modulation circuit for modulating a carrier wave with the signal input, and a second information-containing radio frequency signal is applied to at the modulation circuit for modulating least one of the constellation points of the first modulation.

Communication system with QAM modulation

An optical transmitter for generating a modulated optical signal to be transmitted over fiber optical link. The transmitter includes: an optical source for producing an optical signal; an optically linearized modulator (OLM) as external modulator for modulating the optical signal produced by the optical source with an information carrying signal. The external modulator includes a first input port for receiving a first DC bias signal, and a second input port for receiving a second DC bias signal. The optical transmitter further includes a pilot tone generator for generating a first pilot signal to be applied to the first input port and a second pilot signal to be applied to the second input port. The first and second pilot signals are capable of producing distortion products in the modulated optical signal. A differential modulation signal is imposed onto either the first pilot signal or the second pilot signal so as to generate a first control signal that alternately adjusts the first DC bias signal and the second DC bias signal in order to minimize the distortion products. The optical transmitter may include a digital based control system that is adapted to reduce composite even and odd order distortions in the OLM.

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Doylestown, PA, United States of America

John Caton