Multiple negative differential conductance peaks in interband cascade lasers

We report multiple negative differential conductance (NDC) features observed under both forward and reverse bias voltages in hybrid-cladding interband cascade lasers (ICLs). The ICL with an emission wavelength of 2.77 μm at 300 K has a threshold current density of 183 A/cm2, which is lower than previously reported values from type-II ICLs at similar and somewhat longer wavelengths. The number of NDC peaks aligns with the number of cascade stages and the current densities of the peaks are below 100 and 1 mA/cm2 for reverse and forward bias voltages, respectively, with a peak to valley current ratio of 1.8 and 1.7, respectively, at 80 K. These NDC features are observable at temperatures above 400 K under reverse bias and up to 160 K under forward bias. Hysteresis was observed with these NDC features. Since the unique features discovered in this work are inherently correlated with resonant tunneling in quantum well structures and interband transitions in ICLs, they may help improve understanding of carrier transport dynamics and provide insights into further development of ICLs as well as other potential applications.