HIGH-PERFORMANCE DENSE FDM COHERENT OPTICAL NETWORK

We present the results obtained with a densely-spaced FDM optical star network providing random channel selection by a digitally-tuned high-sensitivity heterodyne receiver. The experimental system consists of six 200 Mb/s FSK modulated channels, spaced by 2.2 GHz and multiplexed by a star coupler. Channel selection is performed by a computer-controlled random-access heterodyne receiver having a sensitivity of 74 photons/bit at a BER of 10-9, which is 1.7 dB from the quantum limit. The digital-tuning random-access capability (which depends on the frequency-tuning current relationship of the LO laser) is protected against frequency drifts of the LO laser. The receiver can also detect the absence of a selected channel. In this case, the receiver locks to the next available channel and displays which channel is received instead. The results obtained indicate that this system has a potential throughput of 2000 Gb/s. © 1990 IEEE