Speaker: Ventsislav K. Valev
Title: Polarization-Resolved Nonlinear Optical Activity in Scattering
Abstract: Nonlinear optical activity in scattered light, first predicted in 1979, has recently become experimentally accessible. The original theory encompassed both elastic scattering and its inelastic counterpart, hyper-Raman. In elastic scattering, depending on the ratio between particle size and wavelength, light scattering is typically classified into Rayleigh, Mie, and Tyndall regimes. Their nonlinear counterparts, hyper-Rayleigh, hyper-Mie, and hyper-Tyndall scattering, arise when the emitted light occurs at harmonic frequencies of the excitation. In chiral systems, these processes give rise to optical activity, manifesting as differences in the scattered intensity for opposite polarizations. Recent experiments have established nonlinear optical activity across multiple scattering regimes and harmonic orders; even and odd order nonlinearities follow distinct selection rules and probe different aspects of nanomaterials. We have further shown that chiral nanoparticles can transfer chirality to achiral molecules, giving riseto both Raman and hyper-Raman optical activity.
So far, however, nonlinear optical activity in scattering has primarily been detected through intensity-based measurements. In this talk, I will present some of our latest results demonstrating that chirality can also be directly encoded in the polarization state of the scattered light. This observation opens another dimension for probing nonlinear chiral light–matter interactions, in both elastic and inelastic scattering regimes.
Bio: Ventsislav K. Valev is a Professor of Physics – Laser Nanoscience, and Associate Dean (Research) at the University of Bath, UK. He is internationally recognized for his work in nanophotonics and nonlinear optics, and is a Fellow of Optica, SPIE, the Institute of Physics, and the Royal Society of Chemistry. In 2023, he was awarded the Thomas Young Medal by the Institute of Physics, and he has developed a substantial, award-winning outreach program.
Zoom meeting ID 832 7181 0349 Password 520698