Study of the spectra of arched-cavity quantum-cascade lasers

The temperature characteristics of arched-cavity quantum-cascade lasers with different geometrical dimensions emitting in the spectral range of 7–8 $\mu$m are studied. The laser heterostructure was grown by molecular-beam epitaxy. The active region consisted of 50 cascades based on a heteropair of In$_{0.53}$Ga$_{0.47}$As/Al$_{0.48}$In$_{0.52}$As solid alloys. Single-mode lasing is demonstrated for lasers with the semicircular cavity segment 100 $\mu$m in diameter and the linear segment 1 mm long. The maximum side-mode suppression ratio at a temperature of 290 K was 26 dB, and the emission wavelength was 7.73 $\mu$m.