Emcore Corporation

Gustav Witzel

Ronald T Logan, Jr

Eva Peral

John Caton

Patrick J Cawthorne

Frank Weiss

Joseph Hober

John Klima

An optical communication system for generating and transmitting a modulated optical signal in which light emitted by a light source is modulated by an optical modulator in accordance with an input electrical signal. A bias signal generator applies a bias electrical signal to bias the optical modulator at a bias angle away from quadrature. The bias signal generator monitors the input electrical signal and adjusts the applied bias electrical signal in dependence on the input electrical signal. The system further includes a receiver which may include an equalizer coupled to the photodetector of the receiver.

Radio frequency optical communication system

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.

Optical transmitter with adaptively controlled optically linearized modulator

An integrated circuit microcontroller for use in an optical transmitter that generates a modulated optical signal for transmission over dispersive fiber optic links in which a broadband radio frequency signal input is applied to first and second RF inputs of an external modulator for modulating the output of a semiconductor laser. The single integrated circuit is a digital signal processor that performs analog to digital conversion, digital processing, and digital to analog conversion, for producing an analog signals coupled to the input of the modulator, the circuit independently adjusts the DC bias of the first and second RF inputs to control a characteristic of the optical signal, such as noise associated with composite second order (CSO) distortion as a remote receiver.

Integrated circuit for adjusting bias in optical transmitter with external modulator

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Warminster, PA, United States of America

Gustav Witzel