High-efficiency light-wave control with all-dielectric optical Huygens' metasurfaces

Optical metasurfaces have developed as a breakthrough concept for advanced wave-front engineering enabled by subwavelength resonant nanostructures. However, reflection and/or absorption losses as well as low polarisation-conversion efficiencies pose a fundamental obstacle for achieving high transmission efficiencies that are required for practical applications. Here we demonstrate, for the first time to our knowledge, highly efficient all-dielectric metasurfaces for near-infrared frequencies using arrays of silicon nanodisks as meta-atoms. We employ the main features of Huygens' sources, namely spectrally overlapping electric and magnetic dipole resonances of equal strength, to demonstrate Huygens' metasurfaces with a full transmission-phase coverage of 360 degrees and near-unity transmission, and we confirm experimentally full phase coverage combined with high efficiency in transmission. Based on these key properties, we show that all-dielectric Huygens' metasurfaces could become a new paradigm for flat optical devices, including beam-steering, beam-shaping, and focusing, as well as holography and dispersion control.