Fig. 2: Far- and near-field characterizations of SPhP-driven qBICs. | Nature Photonics

Fig. 2: Far- and near-field characterizations of SPhP-driven qBICs.

From: Angular dispersion suppression in deeply subwavelength phonon polariton bound states in the continuum metasurfaces

Fig. 2

a, Illustration of the metasurface unit cell with relevant geometrical parameters (top) and tilted scanning electron microscopy image of a portion of the fabricated array (bottom). Scale bar, 500 nm. b, Sketch of the polarization direction in the transmission FTIR measurements. c, Simulated (top) and experimental (bottom) far-field transmission spectra for a metasurface with S = 1 and varying tilting angle β. d, Radiative Q factor extracted from the TCMT fit of the experimental data in c. e, Sketch of the sSNOM setup for the near-field mapping. f, Simulated (top) amplitude (left) and phase (right) of the out-of plane component of the surface electric field at the qBIC resonance frequency. The near-field amplitude and phase measured with sSNOM (second demodulation order, indicated as sO2) are shown in the bottom. g Same as in f, but at a frequency of a higher-order mode that does not show a qBIC character. Scale bar, 500 nm.

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