Two-dimensional reconfigurable gradient index memory metasurface

Creation and control of spatial gradients in electromagnetic properties is a central theme underlying optical device design. In this work, we demonstrate that through modification of the spatial and temporal distribution of current, we can obtain increased control over the shape of these gradients. We are able to write spatially sharp gradients with ∼50% change in the index of refraction over length scales of only a few wavelengths as observed through diffraction limited terahertz spectroscopy. Furthermore, we assess the potentials for such gradients for beam-steering applications.