Fig. 4: High-quality factor radial metalenses for focusing along two dimensions.

a Measured field intensity at the focal plane (x–y plane) on resonance at λ = 1276 nm of a high-Q metalens with 0.1 NA. b Measured field intensity along the optical axis in the x–z plane on resonance. c Measured field intensity at the focal plane off-resonance at a representative wavelength λ = 1266 nm. d Measured field intensity along the optical axis in the x–z plane off-resonance. The scaling of the color maps in (a–d) is identical. e Measured spectral focusing efficiency of the metalens with 0.1 NA and Q = 531. The red line shows a Fano fit to the measurement. f Measured quality factors of fabricated lenses with different resonance wavelengths and numerical apertures of 0.1 (blue disk), 0.18 (red circle), 0.4 (yellow cross), 0.6 (purple plus), and 0.8 (green asterisk). g–j Measured field intensity (field int.) at the focal plane (x–y plane) on the resonance of four high-Q metalenses with numerical apertures of 0.18, 0.4, 0.6, and 0.8, respectively. The resonance wavelengths are 1266 nm, 1291.8 nm, 1285.5 nm, and 1281.4 nm, respectively. The insets denote the full width at half maximum (FWHM) of the focusing. The metalenses are 100 μm in diameter P = 736 nm and H = 695 nm.