Intensity-dependent reflectance modulation of femtosecond laser pulses in GaAs nanocylinders with magnetic resonances

Abstract We experimentally demonstrate modulation of reflectance in periodic arrays of subwavelength gallium arsenide nanocylinders with Mie-type resonances due to absorption saturation and changes in the refractive index of the semiconductor material of metasurface. The intensity-dependent reflectance modulation of up to 30% in the vicinity of the magnetic dipole resonance at a low laser fluence below 200 μ J/cm 2 is shown by I-scan measurements

Combined system of precise positioning of pilotless helicopter-type aircraft in the landing area

On-board equipment, ground equipment, and special software have been developed and tested that makes it possible to determine with high accuracy the relative coordinates of a helicopter-type unmanned aerial vehicle relative to a quick deployment runway in the absence of signals from global navigation systems

Nonlinear response of Q-boosting metasurfaces beyond the time-bandwidth limit

Abstract: Resonant nanostructures, such as photonic metasurfaces, have created an unprecedented case for enhanced light–matter interactions through local field engineering. However, the presence of resonances fundamentally limits the bandwidth of such interactions. Here, we report on amending the nonlinear optical response of a semiconducting metasurface through Q-boosting, where the Q-factor of a metasurface rapidly increases with time. The coupled-mode theory reveals overcoming the bandwidth limit by coupling a broadband signal to a bandwidth-matched resonance and Q-boosting at a timescale faster than a resonator lifetime. A control–excitation experiment simulation using a tailored Q-boosting silicon-germanium metasurface predicts the third-harmonic enhancement by factors of 8 (peak) and 4.5 (integrated) against the best-case static metasurface. An analysis of free-carrier losses based on experimental data shows robustness to nonradiative losses and offers a viable pathway to increasing the light–matter interactions beyond the bandwidth limit, with implications in nonlinear and quantum optics, sensing, and telecommunication technologies

Nonlinear anisotropy in silicon nanoparticle oligomers

In this work, we demonstrate experimentally and numerically an anisotropic nonlinear optical response from silicon nanoparticle oligomers. By monitoring the third-harmonic generation from symmetric silicon nanodisk trimers as a function of the linear pump polarization orientation, we observe considerable variations in the nonlinear signal stemming from the polarization sensitivity of the local field profiles, which otherwise play no role in the symmetry of the nanostructure linear response.The authors acknowledge the support by the Russian Ministry of Education and Science (#14.W03.31.0008), the Russian Foundation for Basic Research (#16-29-11811), and the Australian Research Council