Two-photon absorption in semiconductor nanocrystals

Abstract

Measurements of the two-photon absorption coefficient in semiconductor-doped glasses were performed. The imaginary part of the third-order optical susceptibility in the semiconductor particles is derived by combining nonlinear-optical-transmission data with small-angle neutron-scattering (SANS) results, which give the volume fraction of the nanocrystals. We find that the absorptive nonlinearity of the nanocrystals (with radii, also measured by SANS, in the range 2–11 nm) is close to that of the bulk semiconductor, in contrast to recent predictions and data.