p/2 Alternate-Phase On-Off Keyed 42.7 Gb/s Long Haul Transmission Over 1980 km of Standard Single Mode Fiber

We present 42.7 Gb/s return-to-zero on-off keying pulse-overlapped 1980-km transmission experiments on standard single mode fiber, which compare the performance of the 33%-duty-cycle p/2 alternate- phase format to the 33%-duty-cycle return-to-zero and the 67%- duty-cycle carrier-suppressed return-to-zero on-off keying formats. We show that an effective reduction in nonlinear transmission penalty from intra-channel four wave mixing can be achieved in systems where strong pulse overlap occurs. Experiments show an increased optimum launch power of 2 dB can be realized with the p/2 alternate-phase format resulting in a >3 dB improvement in Q as compared to the return-to-zero and carrier-suppressed return-to-zero formats due to a reduction in intra-channel four wave mixing.