A lightwave system demonstration of microwave subcarrier multiplexing.

We present a demonstration of subcarrier multiplexing in a lightwave multiple-access network. Three 44 Mb/s digital signals are transmitted along a single-mode fiber bus by intensity- modulating two 1.3micron wavelength, multimode laser diodes with FSK subcarriers, at frequencies between 3.5 and 4.0 GHz. If many more channels were added, shot-noise would limit the ratio of the total usable bandwidth to the received photocurrent per channel, (i(dc)), to approximately 2.8 GHz/muA. In the demonstration system, where i(dc) = 2.5muA, the shot-noise limit should permit at least 72 digital video (44 Mb/s) channels.