INTERBAND NEAR-INFRARED 2ND-HARMONIC GENERATION WITH VERY LARGE CHI(2)(2-OMEGA)/ IN ALSB/GASB-INASSB/ALSB ASYMMETRIC QUANTUM-WELLS/

We propose a novel steplike quantum-well structure for second-harmonic generation with very large \chi(2)(2omega)\ in the near infrared, bas ed on interband doubly resonant transitions. The structure is engineer ed so as to maximize the second-order susceptibility chi(2)(2omega), w hich requires, in particular, avoiding too much overlap between the he avy-hole and the lowest electron envelope functions. We show that the choice of a steplike asymmetry and of GaSb-InAsSb compounds, instead o f the conventional AlGaAs, leads to an enhancement of the second-order susceptibility by about 30 times with respect to bulk GaAs, at pump w avelengths of 1.5 mum.