Broadband tunable lossy metasurface with independent amplitude and phase modulations for acoustic holography

Abstract

Abstract Metasurface-based acoustic hologram projectors fabricated with fixed microstructures can only generate the predesigned images at a single or few discrete frequencies. Here, a variety of acoustic holographic applications can be realized in broadband by a matched helical design of the tunable lossy acoustic metasurface (TLAM). The proposed TLAM unit is composed of a grating channel and an adjustable internal absorber to achieve the independent amplitude and phase modulations (APM) in a continuous frequency range. We demonstrate the excellent performance of the scattering-free anomalous refection by the APM method for tuning loss without foam materials. Then, the multi-plane acoustic holograms and the broadband holographic images are demonstrated by the flexible reconfigurations of one designed TLAM. Due to the compact design and the great flexibility, this proposal may be more practical to achieve the high-quality holograms with multi-scale fine manipulation and multiplexed acoustic communication with high information content.