Impact of IF Fluctuations on the Performance of Heterodyne ASK Lightwave Systems

Abstract

This paper examines the performance of heterodyne ASK lightwave systems in the presence of intermediate frequency (IF) errors. To this end, bit error rates (BERs) and sensitivity penalties due to IF error are calculated. Numerical simulations are used to verify theoretical calculations. The results show that the impact of IF error on system performance is more critical for small laser linewidths and/or high-speed heterodyne ASK lightwave systems. When the IF error is Af=0.5R b , to achieve BER = 1CT 9 the required IF SNR is 23.16 dB for zero laser linewidth, which is 3.9 dB worse than the accurate IF case; whereas, for the same IF error the required IF SNR for BER=10~9 is 20.32 dB when the laser linewidth Av = 0.16R b , which implies that the sensitivity penalty is only 0.22 dB.