Generation and Detection of a 56 Gb/s Signal Using a DML and Half-Cycle 16-QAM Nyquist-SCM

A 16-QAM signal is generated using subcarrier modulation with a subcarrier frequency of half the symbol rate, Nyquist pulse shaping, and a directly modulated passive feedback laser at bit rates of 14, 28, and 56 Gb/s. Using polarization multiplexing emulation, a pre-amplified direct detection receiver and digital signal processing, loss margins of 12.6 and 8 dB are achieved for a 112 Gb/s dual polarization signal at back-to-back and after 4 km transmission, respectively.