The room temperature operation of InAs∕AlSb quantum cascade lasers is reported. The structure, grown by molecular beam epitaxy on an InAs substrate, is based on a vertical transition design and a low loss n+-InAs plasmon enhanced waveguide. The lasers emitting near 4.5μm operate in pulse regime up to 300K. The threshold current density of 3.18-mm-long lasers is 1.5kA∕cm2 at 83K and 9kA∕cm2 at 300K.

Quantum cascade lasers emitting at wavelengths as short as 3.1–3.3μm are reported. Such high intersubband emission energies (up to 400meV) have been obtained thanks to the high conduction band offset of the InAs∕AlSb material system. The structures, grown by molecular beam epitaxy on InAs substrates, are based on the bound-to-continuum design and use a low loss plasmon enhanced waveguide consisting of n+-InAs cladding layers with InAs∕AlSb superlattice spacers surrounding the active zone. The lasers exhibit threshold current densities close to 3kA∕cm2 at 83K and operate in pulsed mode up to 240K.

The InAs∕AlSb material system is a promising candidate for the development of short wavelength quantum cascade lasers because of the large conduction band offset of 2.1 eV. In this letter, we present a study of room temperature electroluminescence of InAs∕AlSb quantum cascade structures as a function of the emission wavelength. Intersubband emission with a transition energy of 500 meV (λ=2.5μm) has been obtained.