Abstract:
The lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-$\mu$m under current pumping are demonstrated. The quantum-cascade laser heterostructure is grown by molecular-beam epitaxy technique. Despite the relatively short laser cavity length and high level of external loss the laser shows the lasing in the temperature range of 80–220 K. The threshold current density below 4 kA/cm$^2$ at 220 K with the characteristic temperature $T_0$ = 123 K was demonstrated.