OPTICAL SIGNAL TRANSMITTER, SYSTEM AND METHOD OF TRANSMISSION

摘要

An optical signal transmitter (10) comprises a coherent light generator (12) for generating a carrier wavelength and a modulating means (16, 32) coupled with the output of the light generator. The modulating means has a series arrangement of an optical intensity modulator (16) and an optical phase modulator (32) coupled between the input and an output of the modulating means. The intensity modulator (16) has an input (26) for a non return to zero (NRZ) digital signal of a predetermined data rate as defined by a clock generator. The phase modulator (32) has an input coupled with the clock generator which provides pulses to the phase modulator at the data rate, or at an even multiple of the data rate, but phase shifted relative to the data signal such that one end of each digital period is red shifted and the other end is blue shifted to facilitate detection.