Beyond the Limits of Single Resonance Huygens' Metasurfaces

Huygens' metasurfaces have enabled high efficiency electromagnetic wavefront manipulation based on subwavelength resonant particles. Utilizing co-located single electric and magnetic resonances, they provide perfect transmission in an ultrathin meta-atom configuration. However, by using only single resonances, there is an inherent limitation on the achievable bandwidth and phase coverage which essentially limits the metasurface applications. In this paper, we review these fundamental limitations of Huygens' metasurfaces and show how the bandwidth may be optimized within the constraints of single resonance meta-atoms. We then propose a design methodology to obtain Huygens' metasurfaces with two electric and two magnetic resonances in a single meta-atom configuration, paving the way for further metasurface bandwidth improvement.