Periodic Dielectric Metasurfaces with High-Efficiency, Multiwavelength Functionalities

4 years ago

Periodic Dielectric Metasurfaces with High-Efficiency, Multiwavelength Functionalities

Jonathan A. Fan, Jianji Yang, David Sell, Sage Doshay

Metasurfaces are thin-film optical devices for tailoring the phase fronts of light. The extension of metasurfaces to multiple wavelengths has remained a major challenge, and existing design techniques do not yield devices with high efficiency. This study reports a new design method, based on inverse freeform optimization, that enables high-efficiency, multiwavelength metasurfaces. Using an iterative optimization solver, this study incorporates multiple wavelength responses into wavelength-scale design domains in a straightforward and automated manner. In principle, this method can readily scale to a very large number of wavelengths. As a proof of concept, this study designs and characterizes periodic transmissive metasurfaces, made from silicon, that deflect N different incident near-infrared wavelengths to N unique diffraction orders. The theoretical and experimental efficiencies of these devices scale as 1/N0.5, which is significantly better than current state-of-the-art devices. The implementation of large-angle, broadband blazed grating devices is also demonstrated. This study envisions that this inverse design method can generalize to high-performance, multiwavelength, aperiodic devices, and that it serves as a potential route to broadband metasurfaces. An inverse optimization design method that can produce high-efficiency, multiwavelength metasurfaces is reported. As a proof of concept, periodic transmissive metasurfaces made from silicon are designed and characterized. These devices deflect N different incident near-infrared wavelengths to N unique diffraction orders, and their absolute efficiencies scale as 1/N0.5, which is significantly better than current state-of-the-art devices.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adom.201700645