White-light Polarization-insensitive Metasurface through All-dielectric Anisotropic Nanoresonators

Polarization insensitive optical metasurfaces have gained great prospects in both consumer and industrial products like virtual reality and multimedia devices. All existing designing techniques based on isotropic and anisotropic unit cells encounter a limited bandwidth issue of such optical metadevices, which is an essential requirement of white light digital displays. Here we have proposed a new phase modulation technique that is based on mergence of geometric phase (PB-Phase) and propagation phase to break this conventional tradeoff between bandwidth and polarization insensitivity. And for that, we have employed an array of GaN made anisotropic nanoresonators which are rotated parallelly and anti-parallelly to each other. As a result, we have achieved a constant wavefront manipulation for all incident polarizations for the whole visible regime. Our simulated efficiencies are 73%, 90%, and 72% for the blue (λ=488 nm), green (λ=532 nm), and red light (λ=633 nm).