Science Daily September 20, 2021
In 3D isotropic liquids, optical third-harmonic generation is forbidden, with circularly polarized light (CPL). Yet the associated nonlinear susceptibility directly influences the optical properties at the fundamental frequency by intensity dependence. An international team of researchers (UK, Germany) has revealed the hidden third-harmonic optical properties upon circularly polarized light (CPL) by demonstrating a new effect, in hyper-Rayleigh scattering. The intensity of light scattered at the third-harmonic frequency of the CPL incident light depends on the chirality of the scatterers. It is referred to as third harmonic (hyper) Rayleigh scattering optical activity (THRS OA) and was observed from Ag nanohelices randomly dispersed in water. They provided the first analytical theory model for the new effect in nanohelices, highlighting the role of localized transition dipoles along the helical length. The new effect could find applications in hyper-sensitive characterization of the chirality in molecules and in nanostructures; chirality plays a fundamental role in the function of bio/nano-machinery, with promising applications in next generation technologies…read more. Open Access TECHNICAL ARTICLE
Illustration of the user-friendly experimental setup for measuring third-harmonic Rayleigh scattering. …Credit: Laser & Photonics Reviews, 15 September 2021