Single-mode quantum-cascade lasers with variable etching depth of grating slits

The results of the study of surface-emitting quantum-cascade lasers with a ring cavity radius of 284 $\mu$m were presented. The use of a grating with a variable etching depth (up to 4.6 $\mu$m) provided a single-mode lasing at a wavelength of 7.42 and 7.66 $\mu$m at a temperature of 85 and 293 K. The maximum side-mode suppression ratio was 23 dB at 293 K. The characteristic temperature $T_0$ was 166 K.