Impact of monolithic saturable absorber on the performance of subharmonically mode-locked lasers at millimeter-wave frequencies

A detailed comparison of the characteristics of 40-GHz pulses from a subharmonic mode-locked monolithic laser diode with and without saturable absorber (SA) is demonstrated, in terms of timing jitter, frequency detuning, amplitude modulation, and extinction ratio. The experimental results show that saturable absorption in laser cavity improves the extinction ratio and suppresses amplitude modulation and timing jitter, while no SA section in laser cavity is cost-effective and offers subharmonically mode-locked pulses a larger frequency detuning range.