MULTICHANNEL SYSTEM-DESIGN USING OPTICAL PREAMPLIFIERS AND ACCOUNTING FOR THE EFFECTS OF PHASE NOISE, AMPLIFIER NOISE, AND RECEIVER NOISE

We present a rigorous and accurate model for multichannel direct detection systems where optical preamplification is used. The model accounts for the influence of an optical bandlimiting filter as well as of a polarization filter. Effects of laser phase noise, spontaneous emission noise from the amplifier and of shot noise and thermal noise in the receiver front end are accounted for. For a single optical channel without any phase noise or receiver noise and with a polarization filter our model is in agreement with exact results from Henry who specifies a limiting 10(-9) error-rate sensitivity of 76 received photons. The predicted phase noise penalty for that single channel configuration is found to be close to earlier results from Foschini, Greenstein, and Vannucci as well as to results by Tonguz and Kazovsky. The omission of a polarization filter is found to degrade the system sensitivity less than 1 dB for a single channel with a linewidth less than the bit rate. For multichannel system design we find that a system with many optical channels and no phase noise should have a channel separation of 9.4 bit rates to have less than 1 dB worst-case crosstalk penalty. For a linewidth of 27% of the bit-rate in each channel the required spacing increases to 27 bit rates or more.