Europhysics Letters (EPL)
Novel approach to nonlinear susceptibility in semiconductors
Monique Combescot, Odile Betbeder-Matibet, K. Cho, Hiroshi Ajiki
Abstract
We here propose a new procedure to derive a general expression of the third-order susceptibility valid for any semiconductor Hamiltonian. It relies on our theory for composite exciton many-body effects which is quite appropriate to this problem since all optical nonlinearities in semiconductors come from exchange scatterings with the virtual excitons coupled to photons. Our expression of χ (3) is sample volume free, as physically expected. It also contains a Pauli term (exchange without Coulomb) which is missed by all bosonized exciton approaches. This term, dominant at large detuning, is a direct manifestation of the exciton composite nature.