Continuous wave operation of InAs/InAsxSb1−x midinfrared lasers

Effective band gaps of type-II superlattices (SLs) can cover a wide infrared wavelength range, even beyond the narrowest band gap of any natural antimonide semiconductor alloys. This letter reports the first InAs/InAsxSb1−x type-II SL lasers with cw, optically pumped operation up to 95 K. The stimulated emission results from spatially indirect transitions of relatively extended electron states in the InAs/InAsxSb1−x SL conduction band to the hole states that are localized in the InAsx Sb1−x layers. The lasing wavelength is around 3.3–3.4 μm. Equivalent threshold current densities are estimated to be 3.3 and 56 A/cm2 at sample temperatures of 5 and 95 K, respectively. The characteristic temperature (T0) is approximately 32 K. These results demonstrate that the InAs/InAsxSb1−x type-II SL clad by AlAs0.16Sb0.84 ordered-alloy layers is a promising material system for midwave infrared semiconductor lasers.