Bit-error-rate saturation due to mode-partition noise induced by optical feedback in 1.5-µm single longitudinal-mode C3and DFB semiconductor lasers

We report first measurements of the effect of optical feedback on the bit error rate (BER) as a function of received power of single longitudinal mode cleaved-coupled cavity (C³) and distributed-feedback (DFB) semiconductor lasers. Mode-partition noise, induced by the optical feedback, can cause a bit error-rate floor for large optical feedbacks, but it is shown that high-performance C³lasers and especially DFB lasers can withstand very large optical feedbacks without system degradation.