Impact of in-band crosstalk signals with different duty-cycles in M-QAM optical coherent receivers

Abstract

Optical coherent technology leads to the coexistence of signals with different modulation formats and different bit rates in optical networks. Due to this coexistence, several in-band crosstalk scenarios are possible. In this work, the impact of in-band crosstalk due to M-QAM interferers on the performance of PDM-QPSK and PDM-16-QAM coherent receivers at a bit rate of 100 Gbps is studied. The influence of the duty-cycle, time misalignment and phase difference between interferers and selected signal on the receiver performance is also assessed. We show that the QPSK signal with a duty-cycle of 33% is, generally, the most tolerant selected signal to in-band crosstalk and the less detrimental interferer to the coherent receiver performance. Additionally, we show that the time misalignment has a strong influence on the in-band crosstalk impact, when the duty-cycles of the interferers or selected signal are low.