Fig. 3: Nonlinear signal enchantment.
From: Metaphotonics with subwavelength dielectric resonators
a Measured scattering spectrum of the optimal AlGaAs disk supporting the quasi-BIC mode and b second harmonic signal as a function of the diameter of the disk for different pump polarizations: linear (black), radial (red), azimuthal (blue). The disc radius is 0.3λ at the fundamental frequency. c Theoretical spectra of optical harmonics from a subwavelength AlGaAs disk excited at resonance frequency 3750 nm (blue curve), off-resonance 3500 nm (gray curve) compared to the AlGaAs film (red). d Measured seventh harmonic intensity from the AlGaAs disk in dependence on the excitation wavelength. Solid symbols are azimuthally polarized excitation; open symbols are radial polarized excitation; gray dots, signal from unstructured AlGaAs film. The disc radius is 0.25λ at the fundamental frequency. e Four-wave mixing signal measured from a silicon nanodisk when the wavelength of the second pump is changed (labeled at the peaks). f FWM signal normalized by the pump intensities (red dots) as a function of the wavelength of the second pump and the simulated spectrum of the electric field enhancement <∣Einc∣2> inside the nanodisk. The disc radius is 0.42λ at the higher frequency. a and b are adapted from7; c and d are adapted from39; e and f are adapted from40
