Optically induced birefringence and dichroism in rigidly held dye molecules

Nonlinear-optical properties of Fluorescein-doped boric acid glass are investigated. By considering a linearly polarized pumping field we were able to obtain a complete expression of the dielectric susceptibility tensor. Utilizing a heterodyne detection polarimeter, we characterized the material at λ = 457.9, 476.5, and 632.8 nm. Large values of the nonlinear susceptibility are observed as well as considerable light-induced changes of the absolute values of the dielectric response. As an example, at λ = 457.9 nm and for a sample thickness d = 100 μm, a concentration C = 1.5 × 10−3 M, and an incident intensity I = 100 mW/cm2, the induced dichroism is Δα/α = 30%, and the birefringence is Δn/n = 3.2 × 10−4.