Automatic $\lambda $ -Control With Offset Compensation in DFB Intradyne Receiver for udWDM-PON

A complete automatic wavelength control for digital coherent receivers, which performs local laser tuning and feedforward frequency offset compensation, is presented. We demonstrate the feasibility of the concept in a 1.25-Gb/s differential phase-shift keying intradyne system, achieving accurate performance with common DFB lasers for cost-efficient optical access networks.