Momentum-space reservoir for saturation suppression in intersubband frequency-conversion devices

Summary form only given. Intersubband processes in asymmetric stepped and double quantum wells represent a promising mechanism for the production of coherent, high-intensity optical pulses at midwave infrared wavelengths. Band structure engineering has led to the experimental observation of second order nonlinear optical susceptibility which are several orders of magnitude larger than those in bulk semiconductors. Here we show that while there are fundamental limits to the maximum conversion efficiency attainable from such devices