Romain Peretti, INL

Résumé : Terahertz (THz) radiation offers a unique window into the low-energy excitations of biological and physical systems, probing collective vibrations and picosecond dynamics. However, the development of THz biophotonics is hindered by the challenge of performing quantitative measurements on complex systems, particularly in highly absorbing aqueous environments where the wavelength-to-sample size extremely mismatches.
In this seminar, I will outline the trajectory of my research toward achieving rigorous THz characterization. Starting with the fundamentals of Terahertz Time-Domain Spectroscopy (TDS), I will discuss the signal processing frameworks necessary to retrieve reliable information from experimental data. I will demonstrate how these methods allow us to probe lattice vibrations and molecular crystal signatures, serving as a « nanostructure fingerprint » for solid-state biological samples.
A significant portion of the talk will be dedicated to THz nanophotonics as a solution to the diffraction limit. I will present our recent results on Split-Ring Resonators (SRRs) and their characterization via s-SNOM. Finally, I will discuss the discovery of exceptional Q-factor hyperbolic phonon-polaritons in 2D layered PbI2. These studies aim to establish a fundamental understanding of THz-matter interaction at the nanoscale, eventually targeting the characterization of macromolecule conformation in their natural environment.