Transmission Efficiency Limit for Nonlocal Metalenses

The rapidly advancing capabilities in nanophotonic design are enabling complex functionalities limited mainly by physical bounds. efficiency of transmission is a major consideration, but its ultimate limit remains unknown for most systems. This study introduces matrix formalism that puts fundamental bound on the channel-averaged any passive multi-channel optical system based only energy conservation and desired functionality, independent interior structure material composition. Applying this to diffraction-limited nonlocal metalenses with wide field view shows must decrease numerical aperture commonly adopted designs equal entrance output diameters. It also reducing size can raise bound. reveals as well provides guidance high-efficiency