Nonlocal metasurfaces for spectrally decoupled wavefront manipulation and eye tracking
This addresses the problem of limited spectral control in flat optics for applications like eye tracking, though it appears incremental as it builds on existing metasurface concepts with specific enhancements.
The researchers tackled the need for high-Q optical elements in imaging and sensing by developing nonlocal metasurfaces with atomically-thin elements, achieving fully-decoupled optical functions at different wavelengths and demonstrating a potential application in eye tracking with unperturbed visible vision and near-infrared imaging.
Metasurface-based optical elements typically manipulate light waves by imparting space-variant changes in the amplitude and phase with a dense array of scattering nanostructures. The highly-localized and low optical-quality-factor (Q) modes of nanostructures are beneficial for wavefront-shaping as they afford quasi-local control over the electromagnetic fields. However, many emerging imaging, sensing, communication, display, and non-linear optics applications instead require flat, high-Q optical elements that provide notable energy storage and a much higher degree of spectral control over the wavefront. Here, we demonstrate high-Q, nonlocal metasurfaces with atomically-thin metasurface elements that offer notably enhanced light-matter interaction and fully-decoupled optical functions at different wavelengths. We illustrate a possible use of such a flat optic in eye tracking for eye-wear. Here, a metasurface patterned on a regular pair of eye-glasses provides an unperturbed view of the world across the visible spectrum and redirects near-infrared light to a camera to allow imaging of the eye.