Single-Order Transmission Diffraction Gratings based on Dispersion Engineered All-dielectric Metasurfaces

摘要

A single-order transmission diffraction grating based on dispersionengineered all-dielectric metasurfaces is proposed and its wavelengthdiscriminating properties have been theoretically described and confirmed usingnumerical simulations. The metasurface is designed using a 2D array ofall-dielectric resonators, which emulates a Huygens source configuration toachieve a perfect match to free-space in broad bandwidth. Using a holeydielectric nanodisk structure as the unit cell, the resonant wavelength istapered across the metasurface to engineer the wavelength dependent spatialphase gradient, to emulate a dispersive prism. Consequently, differentwavelengths are steered towards different directions and thus are discriminatedon the output image plane. Due to subwavelength periodicities involved, thewavelength discrimination is achieved directly in the zeroth diffraction orderof the device, unlike conventional diffraction gratings, thereby providing ahigh efficiency wavelength discriminating device.