QUANTITATIVE THEORY OF 3RD-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, chi((3))(-3 omega ;omega,omega,omega), in our superlattice and identify the processes wh ich dominate the response. Features of the band structure are related to the magnitude and frequency dependence of chi((3))(-3 omega;omega,o mega,omega) We find that these structures can be designed to exhibit l arge nonlinear responses by exploiting band-structure engineering.