Robust enhancement of high-harmonic generation from all-dielectric metasurfaces enabled by polarization-insensitive bound states in the continuum

Abstract

The emerging all-dielectric platform exhibits high-quality (Q) resonances governed by the physics of bound states in the continuum (BIC) that drives highly efficient nonlinear optical processes. Here we demonstrate the robust enhancement of third-(THG) and fifth-harmonic generation (FHG) from all-dielectric metasurfaces composed of four silicon nanodisks. Through the symmetry breaking, the genuine BIC transforms into the high-Q quasi-BIC resonance with tight field confinement for record high THG efficiency of 3.9 × 10−4 W−2 and FHG efficiency of 4.8 × 10−10 W−4 using a moderate pump intensity of 1 GW/cm2. Moreover, the quasi-BIC and the resonantly enhanced harmonics exhibit polarization-insensitive characteristics due to the special C4 arrangement of meta-atoms. Our results suggest the way for smart design of efficient and robust nonlinear nanophotonic devices.

A multi-mode super-fano mechanism for enhanced third harmonic generation in silicon metasurfaces

“…The inherently rich variety of electric and magnetic multipolar resonances can be spectrally tailored by varying the size and shape of the nanoparticles, which can lead to their mutual overlap and even swap positions in the spectrum. This can give rise to the exotic phenomena, such as the excitation of Fano resonances [18][19][20] , nonradiative modes 21,22 , and resonances associated with bound states in the continuum (BIC) [23][24][25][26] , which possess ultra-high quality factors. High-quality modes supported by all-dielectric metasurfaces in combination with negligible ohmic losses compared to plasmonic devices, low heating, and high excitable mode volume have led to their emerging application for the efficient nonlinear light generation [27][28][29] .…”

“…In particular, the BIC concept is extensively exploited in the generation of enhanced third harmonic generation (THG) in metasurfaces composed of silicon nano resonators with the latest record peak power independent conversion efficiency of 3.9 × 10 −4 W −2 at a peak power intensity of 1 GW cm −2 reported by ref. 26 . Also, in other metasurfaces consisting of materials with a very large nonlinear susceptibility component, such as germanium, gallium arsenide, aluminum gallium arsenide, or zinc oxide, a substantial enhancement of the harmonic generation processes (SHG and THG) has been demonstrated [30][31][32][33] .…”

Ultra-High Quality Factor Resonances in a Pinwheel-Shaped All-Dielectric Metasurface Based on Bound States in the Continuum

“…In 2022, our group proposed a permittivity-asymmetric all-dielectric metasurface, comprising high-index cuboid tetramer clusters with symmetric structural parameters, which supported an uncommon route to design dual-band polarization-insensitive TD quasi-BICs resonators and facilitates their applications in optic and photonic [35]. Lately, Shuyuan Xiao et al demonstrated the alldielectric metasurfaces composed of four silicon nanodisks, in which the high Q-factor resonance with strongly enhanced local fields lead to significant enhancement of the THG and fifthharmonic generation (FHG) signals through the symmetry breaking [36]. The BIC theory provides an excellent idea for realizing multiple Fano and high Q-factors in all-dielectric metasurfaces.…”

Compact ring resonators of silicon nanorods for strong optomechanical interaction

“…In addition, as a well-confined optical mode can facilitate the optomechanical interaction, the concept of bound states in the continuum is a promising platform and has been widely studied with various nanostructures. 51–55…”

“…In addition, as a well-confined optical mode can facilitate the optomechanical interaction, the concept of bound states in the continuum is a promising platform and has been widely studied with various nanostructures. [51][52][53][54][55] Microcavities and waveguides are indeed two important platforms for realizing and tailoring optomechanical interaction, and they can be designed as on-chip elements that are compatible with the complementary metal oxide semiconductor (CMOS) platform, making them promising in various applications. Nevertheless, there are still also some issues to be addressed.…”