A Simple Theory for Excitonic Optical Nonlinearity in Semiconductors

D. S. Chemla

Izo I. Abram

The strong optical nonlinearity of biexcitons in semiconductors necessitates a nonperturbative calculation of the nonlinear-optical susceptibility of the semiconductor and of the propagation equation of the light wave. Such calculations are possible for all light-beam geometries within a simple model in which excitons and biexcitons are treated quantum mechanically as bosons, with no reference to their internal structure. This simple model can account for most experimental observations, while when dephasing and population effects are considered it predicts the appearance of a dephasing-induced extra resonance analogous to that observed in gases or molecular crystals.

Monique Combescot, Odile Betbeder-Matibet, K. Cho +1 more

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.

Tohya Hiroshima

H. Haug

In semiconductors the attractive Coulomb interaction between electrons and holes causes one- and two-photon resonances, known as excitons and exciton molecules, respectively. Large nonlinearities are observed in the spectral vicinity of these resonances. These nonlinearties are well-suited for the realization of optical bistability1),2),3) as has been demonstrated by Gibbs et al. 1)for GaAs and by Miller et al.2) for InSb. The electron-hole correlations, the screening and the energy renormalization are most conveniently calculated by the Green's function formalism. The optical dielectric function can be expressed in terms of the retarded photon self-energy which is also called the polarization function. This connection is not restricted to the linear response regime.

H. Haug