Power budget optimization of STARNET II: an optically amplified direct-detection WDM network with subcarrier control

STARNET-II is a novel optically amplified direct-detection multi-Gb/s WDM LAN developed at Stanford University, Stanford, CA. STARNET-II is simpler than the coherent STARNET-I yet is functionally equivalent. Here, STARNET-II power budget is investigated and optimized. Power allocation between payload and subcarrier control streams at the transmitter, and power splitting ratio between the payload and subcarrier control receivers are investigated and optimized theoretically and experimentally. Critical parameter variations such as electro-absorption modulator nonlinearity, transmitter wavelength and power instability are investigated, and their effect on the power budget is analyzed. With the optimized design, experimental STARNET-II optical layer has a receiver sensitivity of -31.5 dBm at BER=10^-9 corresponding to 23.9 dB SNR, for simultaneous transmission and reception of 1.25 Gb/s payload and 125 Mb/s control data. Including the computer interface, STARNET-II has a power budget of 28.6 dB. For a 10-km network diameter, STARNET-II dispersion margin can support the modulation bandwidth up to 13 Gb/s