Near-unity third-harmonic circular dichroism driven by a quasibound state in the continuum in asymmetric silicon metasurfaces
Authors: Gandolfi M., Tognazzi A., Rocco D., De Angelis C., Carletti L.
Autors Affiliation: CNR-INO (National Institute of Optics), Via Branze 45, Brescia, Italy and Department of Information Engineering, University of Brescia, Via Branze 38, Brescia, Italy
Abstract: We use numerical simulations to demonstrate third-harmonic generation with near-unity nonlinear circular dichroism (CD) and high conversion efficiency (10-2W-2) in asymmetric Si-on-SiO2 metasurfaces. The working principle relies on the spin-selective excitation of a quasibound state in the continuum, characterized by a very high (>105) quality factor. By tuning multimode interference with the variation of the metasurface geometrical parameters, we show the possibility to control both linear CD and nonlinear CD. Our results pave the way for the development of all-dielectric metasurfaces for nonlinear chiro-optical devices with high conversion efficiency.
Journal/Review: PHYSICAL REVIEW A
Volume: 104 (2) Pages from: 023524-1 to: 023524-8
KeyWords: nonlinear-optical activity; 2nd harmonic generation; fano resonances; chirality; fundamentals; enhancem; lightDOI: 10.1103/PhysRevA.104.023524