Théorique, numérique
Detecting an ultra small amount of matter requires to dramatically confine the EM field in order to improve light-matter interactions. Helmholtz resonators (see figure), composed of a small (ultra-subwavelength) aperture on the surface of a large cavity, funnel light into the cavity through the aperture providing giant local electric field enhancement in the aperture. Helmholtz resonators have been demonstrated as a powerful design for sensing applications. The traditional paradigm of sensing applications is to design a system displaying a high quality factor resonance at a target wavelength (an absorption line of a chemical species to detect). In presence of absorption, the resonant behavior of the system is perturbed. The detection signal that is monitored is limited to this single target wavelength. We have recently demonstrated the possibility of detecting several absorption lines within the IR with a single broadband resonator arising from Helmholtz’s configuration operating in reflection. When depositing a few nanometers layer of material, the reflection of the system displays notable dips at the absorption lines of the layer. The goal of the project is to design sub-wavelength THz resonator arrays (plasmonic metasurfaces) inspired by Helmholtz’s configuration. The internship will focus on the design of devices for molecular fingerprint measurements with a single resonator based metasurface in the THz domain.