Interband cascade lasers near 10 μ m and performance dependence on InAsP layer thickness

We report the operation of interband cascade lasers (ICLs) up to 236 K with emission wavelengths beyond 10 μm. These ICLs utilize modified quantum well (QW) active regions with InAsP barrier layers to promote electron–hole wavefunction overlap for increased lasing wavelength. By comparing ICL wafers with different QW barrier designs, the quantitative effects of InAsP barrier inclusion are evaluated. These effects include reduced threshold current density, longer emission wavelength, improved external quantum efficiency, and higher operating temperature. Utilizing the advantages of the modified QW active region, it is promising to extend efficient ICL operation to longer wavelengths for practical applications, such as free-space communication and heavy-molecule gas spectroscopy.