Meta surfaces with asymmetric gratings for redirecting light and methods for fabrication

摘要

The optical system includes an optically transmissive substrate including a metasurface including a grating that includes a plurality of unit cells. Each unit cell comprising a laterally elongated first nanobeam having a first width; And a laterally elongated second nano-beam spaced from the first nano-beam by a gap, the second nano-beam having a second width greater than the first width. The pitch of the unit cells is 10 nm to 1 占 퐉. The heights of the first nano-beam and the second nano-beam are from 10 nm to 450 nm when the refractive index of the substrate is greater than 3.3; And 10 nm to 1 占 퐉 when the refractive index is 3.3 or less.