Complete amplitude and phase control of light using broadband holographic metasurfaces

TLDR

Holography, which reconstructs light profiles with amplitude and phase information, is valuable for 3D imaging and data storage, but requires subwavelength control of both amplitude and phase, a capability that traditional devices lack, resulting in loss of optical information and noise. The authors propose a metasurface that can independently and fully control amplitude and phase of visible light at subwavelength resolution. This control is achieved with X‑shaped meta‑atoms exploiting an expanded Pancharatnam‑Berry phase concept, enabling full, continuous, broadband amplitude and phase modulation. Experimental demonstrations of complete complex‑amplitude holograms at visible wavelengths with subwavelength resolution showed superior signal‑to‑noise ratios compared to phase‑only holograms, indicating that the metasurface’s extraordinary control capability represents a significant advance toward ideal holography.

Abstract

Reconstruction of light profiles with amplitude and phase information, called holography, is an attractive optical technology with various significant applications such as three-dimensional imaging and optical data storage. Subwavelength spatial control of both amplitude and phase of light is an essential requirement for an ideal hologram. However, traditional holographic devices suffer from their restricted capabilities of incomplete modulation in both amplitude and phase of visible light; this results in sacrifice of optical information and undesirable occurrences of critical noises in holographic images. Herein, we have proposed a novel metasurface that is capable of completely controlling both the amplitude and phase profiles of visible light independently with subwavelength spatial resolution. The full, continuous, and broadband control of both amplitude and phase was achieved using X-shaped meta-atoms based on the expanded concept of the Pancharatnam-Berry phase. The first experimental demonstrations of the complete complex-amplitude holograms with subwavelength definition at visible wavelengths were achieved, and excellent performances with a remarkable signal-to-noise ratio as compared to those of traditional phase-only holograms were obtained. Extraordinary control capability with versatile advantages of our metasurface paves a way to an ideal holography, which is expected to be a significant advancement in the field of optical holography and metasurfaces.