High-Performance, Efficient, Low-Fresnel Number Focusing Metamirror in the D-Band

Metasurface-based optical components are becoming increasingly important due to their unparalleled ability to shape and manipulate electromagnetic waves across a wide range of frequencies, from microwave and terahertz to visible light. In particular, planar meta-mirrors with high efficiency and broad operational bandwidth are expected to play a significant role in shaping channel characteristics for 6G communication links due to their reduced SWaP (size, weight, and power) and integrability. However, achieving large fractional bandwidth and high efficiency simultaneously using metasurface-based mirrors or reflectors have been challenging. In this work, highly efficient broadband focusing meta-mirror has been designed, fabricated and experimentally demonstrated. The device operates in the D-Band (110-170 GHz) and beyond (up to 200 GHz), and exhibits unmatched performance in terms of combined fractional bandwidth (58\%) and energy efficiency, exceeding 53\% over the entire bandwidth with a peak of 77.4\% at frequency 135 GHz. The high performance and advantageous design tradeoffs of this meta-mirror are discussed in terms of the principles of low Fresnel number optics.