R. Noé, S. Hoffmann, C. Woerdehoff, A. Al-Bermani, and M. El-Darawy, “Advances in Coherent Optical Modems and 16-QAM Transmission with Feedforward Carrier Recovery,”10.1117/12.881542__in COHERENT OPTICAL COMMUNICATION: COMPONENTS, SUBSYSTEMS, AND SYSTEMS, 2011, vol. 7960, doi:10.1117/12.881542 .