Scientists from two Swiss institutions have used subwavelength resonant waveguide gratings (RWGs) to create a single-layer, thin-film beam-steering device that can color-filter and redirect a low-coherence white light source, such as light from a smartphone camera’s flash. The RWG-based design, according to the researchers, makes the device “relevant for high-volume production,” in a range of applications in optical security, flat-lens optics, biosensing and near-eye/AR displays.