Second harmonic generation by charge-transfer excitons interacting with phonons

Abstract

Effects of exciton-phonon interaction on the nonlinear optical response of charge-transfer excitons (CTE) are studied in the framework of an exactly solvable model. It is found that the second order excitonic optical polarizability {beta} is modified due to the CTE-phonon interaction. For a nonresonant frequency range, where {beta} is relatively small, the change is not significant. On the contrary, in the vicinity of resonances (when the light frequency {omega}{approximately}{omega}{sub 0} or {omega}{approximately}{omega}{sub 0}/2, {omega}{sub 0} is the CTE transition frequency), the CTE-phonon interaction may remarkably diminish the value of {beta}. This should be taken into account when considering CTE systems in nonlinear optics.