224Gb/s Single Carrier Doubly Differential 2ASK-8PSK System without Carrier Recovery

A carrier-recovery-free 224Gb/s dual-polarization doubly differential 16-point constellation (2ASK-8PSK) is experimentally demonstrated for the first time. Utilizing 10-symbol decision feedback in the 2 nd differential stage, the penalty with respect to conventional 16QAM is only 4.8dB.