Design and parallel implementation of an adaptive baseline wander compensator for high-speed optical coherent receivers

Baseline wander (BLW) is caused by transmission zeros at DC in the frequency response of the communication channel [1]. One of its common sources is a high-pass filter used to AC-couple the received signal. Numerous BLW compensation (BLWC) schemes for baseband and homodyne communication systems have been proposed in past literature. However, a preferred architecture in modern coherent optical communications is the intradyne receiver, because it avoids complex optical phase locked loops. As a result of the carrier frequency offset experienced at the input of intradyne coherent receivers, existing BLWC techniques are not sufficient. In this work we propose an adaptive parallel-processing BLW compensation architecture for high-speed coherent intradyne fiber optic receivers. Parallel processing for the BLWC implementation is imposed by the high data rate required in current optical applications. The new compensator estimates the BLW interference based on both the detected symbols and the carrier frequency offset provided by the carrier recovery loop. Numerical results demonstrate the effectiveness of the proposed technique to mitigate BLW effects.