Nanoelectromechanically Tunable Dielectric Metasurfaces for Reconfigurable Wavefront Shaping

Active metasurfaces promise lightweight and compact reconfigurable optics. Among many other reconfigurable architectures, nanoelectromechanical effects are one of the most effective tuning methods. Various nanoelectromechanical implementations have been demonstrated, but they generally rely on suspended structures that lead to mechanical fragility. In this work, we propose and computationally investigate an on-substrate design with high aspect ratio doped silicon slabs that can achieve a near-2 pi phase response in reflection, utilizing a slot mode at telecom wavelength. An amplitude modulation of 80% and a phase modulation of 1.4 pi can be achieved within 10 V. By adjusting the voltage configuration, switchable beam steering can be achieved reaching up to 58% efficiency utilizing a back-mirror. Beam steering with up to 42% efficiency can be performed by eliminating the back mirror, with the added advantage of easier fabrication. This work paves the way for a solid-state nanoelectromechanical platform for amplitude and phase modulation, wavefront shaping, and beam steering.