EXCITONIC ENHANCEMENT OF 2-PHOTON ABSORPTION IN SEMICONDUCTOR QUANTUM-WELL STRUCTURES

A theoretical treatment of the excitonic enhancement of two-photon abs orption is presented for quasi-two-dimensional quantum-well structures . The two-photon absorption coefficient and the nonlinear index of ref raction are calculated for TM and TE polarizations. Significant enhanc ement is observed in the TM case as a result of excitonic effects. Thi s treatment differs from previous ones in that simple analytical expre ssions are derived. Moreover, we consider the asymptotic behavior as t he size of the quantum well increases toward a three-dimensional syste m.