Optical transmission equipment for non-return-to-zero modulator - incorporates laser diode driven by superimposed currents corresp. to modulating signal, DC bias voltage and smaller clock sine-wave.

摘要

A semiconductor laser (LD) is pulsed by a laser driver (11) providing a current by superposition of an NRZ modulation signal (DT), a bias voltage (BS) and a clock signal (CK). An optical fibre (13) conveys the laser beam to a photodetector (PD), whose electrical output is preamplified (15) and divided between a data regenerator (17) and a clock signal extractor (16). The laser driver incorporates three convertors of the respective input signals into proportional currents, and a combiner. The clock signal is a sinusoid with amplitude smaller than the DC bias voltage. USE/ADVANTAGE - In UHF AM transmission at giga-bit per second rates. Simple and economical circuit structure can extract clock signal continuously without detriment to transmission signal pattern.