High-harmonic generation from a subwavelength dielectric resonator

Abstract

Higher-order optical harmonics entered the realm of nanostructured solids being observed recently in optical gratings and metasurfaces with a subwavelength thickness. Structuring materials at the subwavelength scale allows us toresonantly enhance the efficiency of nonlinear processes and reduce the size of high-harmonic sources. We report the observation of up to a seventh harmonic generated from a single subwavelength resonator made of AlGaAs material. This process is enabled by careful engineering of the resonator geometry for supporting an optical mode associated with a quasi-bound state in the continuum in the mid-infrared spectral range at around λ = 3.7 μm pump wavelength. The resonator volume measures ~0.1 λ 3 . The resonant modes are excited with an azimuthally polarized tightly focused beam. We evaluate the contributions of perturbative and nonperturbative nonlinearities to the harmonic generation process. Our work proves the possibility to miniaturize solid-state sources of high harmonics to the subwavelength volumes.

Enhanced second harmonic generation from supercavity mode and magnetic resonance in dumbbell-shaped silicon nanoblock

“…Therefore, if we could find materials with higher permittivity, it will further enhance our Q factor. Compared with supercavity mode supported by other more high-order magnetic resonance [23][24][25], the energy localization of supercavity mode supported by MQ is weaker. Figures 5(b) and (c) show the SH far-field radiation direction angles in the xoy plane at the two SH peaks to better describe the SHG optical response of the nanoblock.…”

“…In recent years, researchers have applied the supercavity mode, excited by nanoparticles, to various fields, including nonlinear optics and optical sensing, resulting in impressive accomplishments. For instance, they have successfully excited supercavity mode in a cylindrical resonator, enhancing the second and higher harmonics of noncentrosymmetric materials [22][23][24]. Additionally, researchers have designed nano-sized lasers [25] and temperature sensors [26] based on supercavity mode, and have used supercavity mode to enhance photoluminescence emission [27] and excite the nonlinear light source [28].…”

Fast Simulation of Light Scattering and Harmonic Generation in Axially Symmetric Structures in COMSOL

“…From the early years of nonlinear optics, second- and higher-harmonic generation was rightly regarded as an effective tool for frequency conversion. Meanwhile, developing efficient subwavelength sources of SHG is still one of the topical problems of experimental and theoretical nanophotonics. ,− Solution of the SHG problem even in the simplest geometries such as spherical scatterer and plane wave excitation (Mie geometry) is a complex problem, ,, and numerical methods play a crucial role in designing nanophotonic systems. The axial symmetry of the scatterers allows for significantly speeding up the simulations of the SHG by using the azimuthal expansion method.…”

Spectral Tuning of High‐Harmonic Generation with Resonance‐Gradient Metasurfaces

“…[11–14]) toward the studies of nonperturbative nonlinear regimes of light‐matter interaction including multi‐photon absorption [ 15 ] and high‐harmonic generation. [ 16–21 ]…”

“…[11][12][13][14]) toward the studies of nonperturbative nonlinear regimes of light-matter interaction including multi-photon absorption [15] and high-harmonic generation. [16][17][18][19][20][21] Nanoparticles with carefully engineered geometries can support optical modes empowered by Mie resonances, such as optically-induced magnetic dipole resonances, [11] higher-order multipoles, [22] and anapole states, [13] as well as extended lattice modes associated with Fano resonances [12] and bound states in the continuum. [9] High field enhancements near the resonant modes increase the efficiency of nonlinear processes by orders of magnitude.…”