Quantitative theory of third-harmonic generation in an (InAs)0.7(GaSb)0.3/(AlSb) superlattice

We present the results of a full-scale calculation of the third-order susceptibility describing third-harmonic generation in an (InAs${)}_{0.7}$(GaSb${)}_{0.3}$/(AlSb) superlattice. We investigate the virtual excitations which contribute to the third-order susceptibility, ${\mathrm{\chi }}^{\mathrm{}\left(3\right)\mathrm{}}$(-3ω;ω,ω,ω), in our superlattice and identify the processes which dominate the response. Features of the band structure are related to the magnitude and frequency dependence of ${\mathrm{\chi }}^{\mathrm{}\left(3\right)\mathrm{}}$(-3ω;ω,ω,ω). We find that these structures can be designed to exhibit large nonlinear responses by exploiting band-structure engineering. © 1996 The American Physical Society.