Hyper-Rayleigh scattering in solution with tunable femtosecond continuous-wave laser source

Abstract

Hyper‐Rayleigh scattering has been developed as a generally applicable technique for the determination of the first hyperpolarizability β of a wide class of molecules [Clays and Persoons, Rev. Sci. Instrum. 63, 3285 (1992)]. In this article, we show that it is possible to replace the low repetition rate, nanosecond pulse, Q‐switched laser source and fast gated electronics by a self‐mode‐locked, femtosecond pulse, broadly tunable continuous‐wave laser and phase‐sensitive detection. This results in a faster and much simpler measurement procedure. The accuracy of the femtosecond hyper‐Rayleigh scattering set‐up was checked by measuring the first hyperpolarizability β of the octopolar molecule crystal violet in methanol [(450±100)×10−30 esu at 800 nm]. The sensitivity of the instrument allows concentration‐dependence studies, down to the pure solvent.