Potential for Terahertz/Optical, Two Color Non-linear Sensing of Liquid Biochemical Agents

摘要

A high-sensitivity setup for the observation of X(2)-based, terahertz/optical, sum and difference frequency generation in liquids is presented. It relies on launching wavefront modulated terahertz radiation into a liquid traversed by an optical beam. Phase matching and polarization selection rules can be tuned to support three wave mixing via either chiral allowed electric dipole processes or higher order quadrupole/magnetic dipole processes. Under nonresonant excitation, hyperpolarizabilities from quadrupole/magnetic dipole processes are measured. Since this approach does not require terahertz transmission through macroscopic thicknesses of water, it has the potential to open a new window on the terahertz dynamics of water solvated molecules.