Ultra-compact visible light depolarizer based on dielectric metasurface

With rapid development toward shrinking the size of traditional photonic systems such as cameras, spectrometers, displays, and illumination systems, there is an urgent need for high-performance and ultra-compact functional optical elements. Metasurfaces, consisting of an array of subwavelength nanoscatterers with spatially varying geometries, have shown remarkable performance as ultrathin multifunctional optical elements. Here, based on an all-dielectric metasurface, we propose and experimentally demonstrate a spatial domain optical depolarizer capable of efficiently depolarizing linearly polarized light in the visible spectral band from 450 nm to 670 nm, with a degree of polarization of less than 10%. Remarkably, it is capable of depolarizing the light beam with a diameter down to several micrometers, about two orders of magnitude smaller than commercial liquid-crystal-based depolarizers. We envision the metasurface depolarizer to find its applications in the next generation ultra-compact grating spectrometers and illumination systems.With rapid development toward shrinking the size of traditional photonic systems such as cameras, spectrometers, displays, and illumination systems, there is an urgent need for high-performance and ultra-compact functional optical elements. Metasurfaces, consisting of an array of subwavelength nanoscatterers with spatially varying geometries, have shown remarkable performance as ultrathin multifunctional optical elements. Here, based on an all-dielectric metasurface, we propose and experimentally demonstrate a spatial domain optical depolarizer capable of efficiently depolarizing linearly polarized light in the visible spectral band from 450 nm to 670 nm, with a degree of polarization of less than 10%. Remarkably, it is capable of depolarizing the light beam with a diameter down to several micrometers, about two orders of magnitude smaller than commercial liquid-crystal-based depolarizers. We envision the metasurface depolarizer to find its applications in the next generation ultra-compact grating spectro...