BER Performance of Coherent Optical Communications Systems Employing Monolithic Tunable Lasers With Excess Phase Noise

We analyze the bit error rate (BER) performance of optical coherent communication systems employing multi-section monolithic tunable lasers with large excess phase noise. The BER of the coherent system utilizing a second-order decision-directed digital phase-locked loop (DD-PLL) for phase tracking was computed numerically. Experimental results have also been demonstrated with a 16-quadratic-amplitude modulation coherent system deploying a sampled-grating distributed Bragg reflector laser at 16 Gbaud that confirms the performance of the second-order DD-PLL in tracking the excess phase noise.