Crosstalk penalty in multichannel ASK heterodyne lightwave systems

Abstract

This paper addresses the issue of optimum channel spacing in multichannel amplitude-shift-keying (ASK) heterodyne lightwave systems by considering the bit-error-rate (BER) degradation resulting from interchannel crosstalk. An expression for the BER of a specific channel is obtained by considering the crosstalk from both of its nearest neighbors. The general result is used to calculate the power penalty as a function of the crosstalk level. The crosstalk is shown to depend on a large number of system parameters such as the bit rates, the received powers, the channel spacing, and the response function of the bandpass filter (BPF). For the case of equal bit rates and equal received powers in all channels, the crosstalk from each channel should be below -12 dB to keep the power penalty below 1 dB. This requirement translates into a minimum channel spacing of about four or five times the bit rate, depending on whether the filter bandwidth is two or three times the bit rate. If the objective is to reduce the power penalty below 0.1 dB, the interchannel crosstalk should be less than -18 dB. This would require a minimum channel spacing of about ten times the bit rates.

Performance Analysis and Power Tilt Mitigation of Ultra-Wideband WDM Transmission Systems

“…To investigate the effect of nonlinearity on the signal performance of UWB WDM systems, the nonlinear Schrödinger equation for optical pulse transmission in a singlemode fiber is first given as [29]…”