Compensation of quadrature imbalance in an optical 16-QAM digital coherent receiver

摘要

In this paper, the impact of quadrature imbalance (QI) is analyzed for an optical 16-quadrature amplitude modulation (16-QAM) transmission system that employs digital coherent receivers. A compensation method for QI in digital domain is demonstrated using four real-valued filters connected in butterfly configurations and adapted by decision-directed least-mean-square (DD-LMS) algorithm. The effectiveness of the proposed QI compensation scheme is verified by numerical simulations.