Experimental demonstration of tunable phase-noise mitigation and automatic frequency/phase locking for a 20–32 Gbaud QPSK homodyne receiver using optical mixing of nonlinearly generated higher harmonics

We experimentally demonstrate tunable phase-noise mitigation and automatic frequency/phase locking to a “local” pump laser for a 20–32 Gbaud QPSK homodyne receiver using nonlinear optical signal processing. For the input noisy signal, open eye-diagrams are obtained for in-phase and quadrature components and ∼2 dB OSNR gain is achieved at BER 10 −3 .