Magnetic Toroidal Dipole Resonances for Efficient THz Generation in Dielectric Metasurfaces

Year: 2026

Authors: Rocco D., Sergaeva O., Carletti L., Tognazzi A., Franceschini P., Cino A.C., Locatelli A., De Angelis C.

Autors Affiliation: Univ Brescia, Dept Informat Engn, I-25123 Brescia, Italy; CNR, NationalInstitute Opt, I-25123 Brescia, Italy; Natl Inst Opt, Consiglio Nazl Ric, I-25123 Brescia, Italy; Univ Palermo, Dept Engn, I-90128 Palermo, Italy.

Abstract: Nonlinear dielectric metasurfaces represent a rapidly advancing family of optical devices characterized by high nonlinear conversion efficiency with an ultrathin form factor. Here, we report on terahertz (THz) emission through difference-frequency generation (DFG) in an Aluminum Gallium Arsenide (AlGaAs) metasurface supporting magnetic toroidal dipolar resonances at the two pump wavelengths, which nonlinearly interact with each other. The simultaneous excitation of these high-Q resonances, together with the dispersive behavior of the nonlinear susceptibility, enables an exceptionally strong DFG response. Conversion efficiencies around 8 THz exceed those of an unstructured AlGaAs slab of the same thickness by over nine orders of magnitude. These results highlight the potential of DFG metasurfaces as compact and highly efficient platforms for THz generation.

Journal/Review: IEEE PHOTONICS JOURNAL

Volume: 18 (2)      Pages from: 3000107-1  to: 3000107-7

More Information: This work was supported in part by European Union-NextGeneration EU, Mission 4 Component 1-PRIN 2022 Project GRACE6G underGrant 2022H7RR4F CUP D53D23001250001
KeyWords: Metasurfaces; Toroidal magnetic fields; Terahertz radiation; Magnetic resonance; Dielectrics; Terahertz communications; Q-factor; Magnetic susceptibility; Magnetic domains; Dispersion; terahertz radiation; toroidal magnetic fields; dielectric resonator antennas; nonlinear optics
DOI: 10.1109/JPHOT.2026.3663297