Abstract
A lambda similar or equal to 9.7 mu m GaAs/Al(0.45)Ga(0.55)As quantum cascade laser with an In(0.47)Al(0.53)P waveguide is reported that demonstrates record low threshold current densities for the GaAs/Al(x)Ga(1-x)As materials system in the mid-infrared. Under pulsed operation, threshold current densities of 2.2 and 4.4 kA/cm(2) are observed at 240 and 300 K, respectively, and laser emission is maintained up to temperatures of at least 330 K. The laser was grown by metal-organic vapour phase epitaxy, and emits peak optical powers of up to 0.57 W at 240 K and 0.16 W at 300 K.