Numerical Analysis of Nanoblocks as elements of a Phase Gradient Metasurface

We numerically analyzed a proposed gold nanoblock as an element of a phase gradient metasurface working in the visible and near-infrared regime. In contrast to previous designs in the literature, these elements work under off-resonance condition which leads to significantly reduced absorbing losses and improved conversion efficiency, also in this way a broadband operation is achieved. We show that when the excitation field is in the direction of the (short) width of the nanoblock, a condition required so that it works off resonance, by changing the width of nanoblock we can reach up to 2π phase retardation in reflection. We then use this property to design a polarization beam splitter.

Keywords:

Metasurface , Nanoblock , Optical Antenna , LSPR , phase shift