2ND HARMONIC-GENERATION IN GAAS/GAAS ASYMMETRIC QUANTUM-WELLS

Mid-infrared resonant second harmonic generation is investigated in asymmetric quantum wells consisting of Al(x)Ga(l-x)As barriers, a GaAs well, and an Al(y)Ga(l-y)As layer with y < x. The intraband level energies and their related wave functions are evaluated through a self-consistent solution of Schrodinger and Poisson equations. The local second-harmonic generation is based on a non perturbative approach using the density matrix formalism. Results show that values as high as 3.6 X 10(-7) m/V could be obtained for the second harmonic non-linear susceptibility. This is about 950 times the corresponding value in bulk GaAs. The conversion efficiency is then evaluated using a propagation model taking into account the material dispersion along with the dispersion induced by the fields. Conversion efficiency superior to 6% for a pump intensity of 10 MW/cm2 seems feasible.