High Harmonic Generation from a Large-gap Semiconductor Metasurface

Abstract

Efficient generation of even and odd high harmonics from a resonant large-gap semiconductor metasurface interacting with femtosecond mid-infrared pulses is reported.

Trade‐Off between Second‐ and Third‐Order Nonlinearities, Ultrafast Free Carrier Absorption and Material Damage in Silicon Nanoparticles

“…Spatially, we consider a plane wave, therefore, a single NP or NPs in array are irradiated uniformly. In most of the experiments with nanostructures, the focusing conditions are not extremely tight (NA ≈ 0.4 or looser), [3,7,21] corresponding to the beam's waist from several to tens of microns significantly larger compared to the subwavelength size of the considered NPs. Therefore, the uniformity produced by laser focusing is much less pronounced than the uniformity caused by inhomogeneous field distributions at the nanoscale inside the NPs.…”

“…All-dielectric nanostructures, supporting individual Mie or collective resonances, can boost harmonic generation up to record conversion efficiencies in ultrashort laser-matter interactions. [1][2][3][4][5][6][7][8] One of the crucial advantages is a relatively high damage threshold of such materials, in comparison with plasmonic counterparts or unstructured samples. Nevertheless, the limitations due to free carrier absorption losses and material damage are still relevant in pursuit of the optimal laser parameters and geometries for record harmonic enhancement and while paving the way from perturbative to non-perturbative regimes in nonlinear optics.…”

“…On the one hand, these effects are commonly considered as the limiting factors for the operating frequency conversion nanodevices. [1,2,[20][21][22][23] On the other hand, inhomogeneous free carriers can serve as an additional source for symmetry breaking [24,25] and for high-order harmonics generation in non-perturbative regimes, [7,8,26,27] and participate in ultrafast self-action, all-optical switching, and modulation at the nanoscale. [20,[28][29][30][31][32] While the applicability of the perturbative approaches is limited to describe weak intensity regimes, the extended hydrodynamic model for electron-hole plasma kinetics and electron-ion transfer gives a reliable estimate for the inhomogeneous absorption and heating processes inside the laser-excited nanostructures and describes the non-perturbative mechanism of harmonic generation due to direct electron transitions from valence to conduction band.…”

High‐Harmonic Generation Enhancement with Graphene Heterostructures

“…Atomic gases have thus far been the most successful among demonstrated systems for HHG, [ 1,2 ] although they require high vacuum, making them impractical for the design of integrated devices. As a result, the development of solid‐state HHG systems has become an important challenge, with promising results demonstrated for various crystalline materials, [ 3–5 ] in nonlinear meta‐surfaces [ 6–9 ] and proposals have been made to enhance HHG using layered nanostructures. [ 10 ] However, the mechanisms of HHG in solid state appear to be fundamentally different from that in atomic gases, and are highly sensitive to crystal and polarization orientations, [ 11,12 ] as well as to the fundamental optical properties of the materials.…”