Impact of saturable absorption on performance of optical clock recovery using a mode-locked multisection semiconductor laser

This paper investigates the impact of saturable absorption (SA) on the performance of optical clock recovery using a mode-locked multisection laser diode. Optical clock at 40 GHz is recovered from the multisection laser with SA section operated under a range of bias conditions. The dependence of extinction ratio and timing jitter of the recovered clock on required optical injection power, data rate detuning, and mark ratio is also evaluated under these operation conditions. The experimental results show that strong SA effect in laser cavity improves extinction ratio and suppresses timing jitter of the recovered clock, while weak or no SA effect in laser cavity offers clock recovery with larger date rate detuning range defined by timing jitter and less dependence on the variation of data mark ratio for extremely low mark ratio.