Fast Gain Dynamics in Interband Cascade Lasers

Abstract

Interband Cascade Lasers (ICL) have matured into a versatile technological platform in the mid-infrared spectral domain. To broaden their applicability even further, ongoing research pursues the emission of ultrashort pulses. The most promising approach is passive mode-locking with a fast saturable absorber. However, despite vast attempts no passive mode-locked ICL has been demonstrated up to date. In this study, pump-probe measurements are conducted on the ICL gain, demonstrating that ≈60–70% of its dynamic behavior is characterized by a rapid recovery time of 2 ps. The findings explain why passive mode-locking of ICLs has not succeeded so far, shedding a new light on ICL dynamics as strategies are proposed to overcome the current limitations.