Resonant Fully Dielectric Metasurfaces for Ultrafast Terahertz Pulse Generation

^1. Emergent Photonics Research Centre, Dept. of Physics, Loughborough University, Loughborough, LE11 3TU, England, UK
^2. Emergent Photonics Lab (Epic), Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, UK
^3. University of Brescia, Department of Information Engineering, via Branze 38, 25123, Brescia, Italy
^4. Politecnico di Milano, Department of Physics, Piazza Leonardo Da Vinci 32, 20133, Milan, Italy
^5. Matériaux et Phénomènes Quantiques, Université Paris Cité and CNRS, 10 rue A. Domon et L. Duquet, 75013, Paris, France

^* Corresponding author: l.peters@lboro.ac.uk

Published online: 31 October 2024

Abstract

In the framework of optical frequency conversion, metasurfaces have elevated the potential for effective interfacial nonlinear coefficients through various modes of field localization. For the generation of pulsed ultrafast terahertz (THz) signals, metasurfaces present a viable alternative in the domain of surface-scalable sources driven by low-power oscillators (using nJ pulses). However, recent innovations have predominantly relied on surface plasmons (metals) and, more broadly, on excitations within non-transparency windows—conditions that typically impose limitations on applications and the choice of platforms. Here, we demonstrate the utilization of a fully-dielectric, fully transparent semiconductor that exploits surface-nano-structure-mediated resonances alongside its inherent quadratic nonlinear response. Our system exhibits a remarkable 40-fold efficiency enhancement in comparison to the non-decorated substrate.