A MWIR 3D Plasmonic Asymmetric Transmission Metasurface

3D metasurface structures can achieve higher performances (e.g., wider FOV, broader bandwidth, higher efficiency) than their 2D counterparts due to the extra degrees of freedom available to designers. A promising technique to fabricate 3D metasurface structures is membrane projection lithography. In this paper, we present a 3D metamaterial unit cell that is designed to achieve broadband asymmetric transmission in the mid-wave infrared (MWIR) regime. The structure was optimized by pairing a genetic algorithm with a fast periodic finite element boundary integral solver. The metasurface design has a max y- to x-polarization light efficiency of 80% in the forward direction, while transmitting less than 10% in the reverse direction. Moreover, this structure can be fabricated using the membrane projection lithography technique.