PULSED AND CONTINUOUS-WAVE OPERATION OF LONG-WAVELENGTH INFRARED (LAMBDA=9.3 MU-M) QUANTUM CASCADE LASERS

The operation of quantum cascade lasers at a wavelength (lambda simila r or equal to 9.3 mu m) well within the 8-13-mu m atmospheric window i s reported, A detailed study of intersubband luminescence in a vertica l transition structure shows linewidths as narrow as similar to 10 meV at cryogenic temperatures, increasing to 20 meV at room temperature, Pulsed operation is demonstrated up to 220 K with a peak power approxi mate to 10 mW and approximate to 35 mW at 140 K, The temperature depen dence of the threshold current density (J(th)) is described by a high T-0 (128 K), J(th) is also systematically studied as a function of cav ity length to determine the peak gain and waveguide losses, Continuous -wave, single-mode operation is demonstrated up to 30 K with powers ap proximate to 2 mW.