Quasi-Freeform Metasurfaces for Wide-Angle Beam Deflecting and Splitting

Abstract

Metasurfaces attracted extensive interests due to their outstanding ability to manipulate the wavefront at a subwavelength scale. In this study, we demonstrated quasi-freeform metasurfaces in which the radius, location, and height of the nanocylinder building blocks were set as optimized structure parameters, providing more degrees of freedom compared with traditional gradient metasurfaces. Given a desired wavefront shaping objective, these structure parameters can be collectively optimized utilizing a hybrid optimized algorithm. To demonstrate the versatility and feasibility of our method, we firstly proposed metasurfaces with deflecting efficiencies ranging from 86.2% to 94.8%, where the deflecting angles can vary in the range of 29°–75.6°. With further study, we applied our concept to realize a variety of high-efficiency, wide-angle, equal-power beam splitters. The total splitting efficiencies of all the proposed beam splitters exceeded 89.4%, where a highest efficiency of 97.6%, a maximum splitting angle of 75.6°, and a splitting uniformity of 0.33% were obtained. Considering that various deflecting angles, and various splitting channels with different splitting angles, can be realized by setting the optical response of metasurfaces as the optimization target, we believe that our method will provide an alternative approach for metasurfaces to realize desired wavefront shaping.

All-in-One Collimating Splitter Based on a Meta-Fiber Platform

“…In addition, the fabrication of the planar nanostructures of the metasurfaces enjoys good CMOS compatibility, which is much simpler than the multilevel DOE fabrication process. Thanks to the flexibility in manipulating light and the good CMOS compatibility in terms of fabrication, various applications of metasurfaces have been demonstrated, including imaging [9][10][11][12], holography [13][14][15][16], beam steering [17][18][19][20][21][22], beam shaping [23,24] and so on. Recently, metasurfaces based on Dammann grating have been proposed for realizing versatile beam functions in different diffraction orders [25][26][27][28] or switchable functions empowered by tunable materials [29,30].…”

Enhanced Near-Infrared Ultra-Narrow Absorber Based on a Dielectric Nano-Resonant Ring for Refractive Index Sensing

“…In recent years, metasurfaces have garnered significant attention in the fields of optics and communication due to their ability to manipulate the phase, amplitude, and polarization of incident electromagnetic waves through various frequency ranges [1][2][3][4]. One of the most important applications of metasurfaces lies in their ability to be utilized as absorbers.…”