Abstract:

Intersubband electroluminescence is reported in a quantum-cascade structure based on asymmetric superlattice active regions and designed for emission in the THz range (lambdaapproximate to80 mum). Comparison with a structure based on a ``vertical transition'' in a single quantum well shows an increased full width at half maximum (2.8 vs 0.9 meV) of the emission line. In both cases the dependence of the optical power on the injected current is linear or sublinear and remains in the pW range. (C) 2002 American Institute of Physics.