Theory of exciton-exciton correlation in nonlinear optical response

TL;DR

This paper develops a comprehensive theoretical framework for understanding Coulomb interaction effects, including exciton-exciton correlations, in the nonlinear optical response of semiconductors, capturing both bound and unbound biexciton phenomena.

Contribution

It introduces a systematic perturbation theory that unifies the treatment of various exciton-exciton interaction effects in nonlinear optical processes.

Findings

Inclusion of memory effects beyond Markovian approximation.

Unified description of bound and unbound biexcitons.

Proposed approximations for correlation functions.

Abstract

We present a systematic theory of Coulomb interaction effects in the nonlinear optical processes in semiconductors using a perturbation series in the exciting laser field. The third-order dynamical response consists of phase-space filling correction, mean-field exciton-exciton interaction, and two-exciton correlation effects expressed as a force-force correlation function. The theory provides a unified description of effects of bound and unbound biexcitons, including memory-effects beyond the Markovian approximation. Approximations for the correlation function are presented.