Measurements of All-Dielectric Compound Metaoptics for Wavefront Transformation

Reflectionless and lossless metasurfaces can manipulate the propagation of electromagnetic waves by applying a phase discontinuity to a wavefront. While phase-only control is sufficient to perform simple refractive functions, more advanced applications such as establishing custom antenna apertures, forming custom optical beam-splitters, and projecting complex-valued holograms require manipulation of both the phase and amplitude of a wave. Here, we show that a pair of lossless metasurfaces arranged along a common axis (forming a compound metaoptic) can implement phase and amplitude control without loss. We report measurements of compound metaoptics at near-infrared wavelengths, demonstrating a beam-splitter with a custom 4:1 intensity ratio between two output beams.