Geometric-Phase Metalens: Wavefront Shaping

This simulator builds a real Pancharatnam-Berry (geometric-phase) metalens: hundreds of nano-antennas arranged across a flat aperture, each rotated to the exact angle a lens phase profile demands, colored to reveal the concentric Fresnel zones that any flat lens must produce. Because geometric phase flips sign with polarization handedness, the same fixed nanostructure focuses left-circularly-polarized light to a real focal spot while diverging right-circularly-polarized light from a virtual source behind the surface — flip the handedness toggle to watch the reshaped wavefront switch between a converging spherical cap and a diverging one. Redesign the lens with the aperture, focal length and wavelength sliders and watch the numerical aperture, Fresnel-zone count and diffraction-limited spot size update from the same equations that govern real flat-optics metalenses used in holography and imaging.