We demonstrate the large throughput potential of an optical star network using WDM and coherent detection techniques. The demonstration system consists of three optical channels spaced by the minimum frequency interval possible without cochannel interference. We also demonstrate confinement of the optical signals to a comb of equally spaced frequencies by means of a simple technique. Our results indicate that 100,000 users within a radius of 10 km could be Interconnected with such a system in which lasers are FSK modulated at 45 Mbit/s, the channels are spaced by 300 MHz, and each channel is received with an optical power of −61 dBm (113 photons/bit) for a BER of 10−9. This represents a receiver sensitivity of 4.5 dB above the shot noise limit, the best sensitivity yet reported for FSK modulation.
© 1988 Optical Society of AmericaPDF Article