Performance of cascaded misaligned optical (de)multiplexers in multiwavelength optical networks

We use computer simulation techniques to evaluate the limitations on laser misalignment tolerances for multiwavelength optical networks with a cascade of 2 to 100 (de)multiplexers modeled as either first-order filters or third-order Butterworth filters, The results are dependent on the number of (de)multiplexers used, on the bit rate, and on the filter characteristics. We find that both the magnitude and the phase characteristics of the (de)multiplexer transfer function are important in determining the distortion-induced penalties, The allowable laser misalignment tolerances, at 10Gb/s and for systems using (de)multiplexers modeled as third-order Butterworth filters, vary from +/-78 GHz (+/-0.63 nm) for systems with a cascade of 2 filters to +/-18 GHz (+/-0.15 nm) for systems with a cascade of 100 filters.