Metasurface Beam Steering — Generalized Snell's Law

A metasurface is a sub-wavelength array of engineered nano-antennas that stamps a spatially-varying phase onto a wavefront, letting it bend light to angles ordinary refraction can never reach. This simulator renders a real antenna array — colour and rotation encode each element's local phase — sitting at the interface between two identical media, and computes the outgoing beam angle live from the generalized Snell's law, n_t sinθₜ − n_i sinθᵢ = (λ₀/2π)(dΦ/dx). Drag the incidence angle, wavelength and per-cell phase step to watch the anomalous beam swing independently of the dashed ordinary-refraction reference, and push the phase gradient far enough to see the transmitted beam vanish into an evanescent, surface-bound wave.