High temperature laser generation of quantum-cascade lasers in the spectral region of 8 $\mu$m

In this paper, we present studies of the characteristics of quantum-cascade lasers with a generation wavelength in the region of 8 $\mu$m at high temperatures of up to + 65$^{\circ}$C. The characteristic temperatures of the temperature dependences of the threshold current and the differential efficiency are determined. Spectral studies showed the presence of two generation lines with a short wavelength of $\sim$7800 nm and a long-wave wavelength of $\sim$8100 nm. The observed competition between the short-wave and long-wave generation lines leads to a nonmonotonic character of the dependence of the radiation intensity on the pump current.