300 K operation of a GaAs-based quantum-cascade laser at lambda approximate to 9 mu m

The room-temperature (300 K), pulsed mode operation of a GaAs-based quantum -cascade laser is presented. This has been achieved by the use of a GaAs/Al 0.45Ga0.55As heterostructure which offers the maximum Gamma-Gamma band offs et (390 meV) for this material system without inducing the presence of indi rect barrier states. Thus, better electron confinement is achieved, counter ing the loss of injection efficiency with temperature. These devices show s imilar to 100 K increase in operating temperature with respect to equivalen t designs using an GaAs/Al0.33Ga0.67As heterostructure. We also measure 600 mW peak power at 233 K a temperature readily accessible by Peltier coolers . (C) 2001 American Institute of Physics.