Fig. 2: Versatile radial BIC resonances and polarization invariance.
From: Radial bound states in the continuum for polarization-invariant nanophotonics
Electric near fields for a symmetric radial BIC (ΔL = 0 nm) in a and several symmetry-broken radial quasi-BIC (ΔL > 0 nm) geometries in b. c Optical transmittance spectra of the radial BIC structures show a resonance redshift with increasing radii, as illustrated in the gray-scale optical micrograph. d Dependence of the quality factor on the ring radius R and the unit cell asymmetry ΔL. Quality factors exceed 500 for ΔL = 25 nm in the visible wavelength range. e The radial BIC geometry shows polarization invariance as observed by the weak dependence of the resonance quality factor on the polarization angle of the incident light \(\varphi\).
