Role of the band structure in determining the third-order susceptibility of semiconductor superlattices

We show that both the absolute value and the sharp features in the spectral form of the frequency-dependent third-order susceptibility of semiconductor superlattices (e.g., [8 monolayers (InAs${)}_{0.7}$(GaSb${)}_{0.3}$]/(4 monolayers AlSb)) strongly depend on the shape of the minibands. The significant minibands span a range of energies up to ≊${\mathit{E}}_{\mathrm{gap}}$ from the fundamental band edges.