Ultrathin and multicolour optical cavities with embedded metasurfaces

• Published in: Nature communications Vol. 9; no. 1; pp. 2673 - 7
• Main Authors: Shaltout, Amr M., Kim, Jongbum, Boltasseva, Alexandra, Shalaev, Vladimir M., Kildishev, Alexander V.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10-07-2018; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/399/1015; 639/624/399/1098; 639/624/400/1021; 639/624/400/1103; Biosensors; Embedded systems; Embedding; Filtration; Holes; Humanities and Social Sciences; Image resolution; Interferometry; Metasurfaces; Mirrors; multidisciplinary; Optical components; Photonics; Polymers; Propagation; Science; Science (multidisciplinary); Silver; Spatial discrimination; Spatial light modulators; Spatial resolution; Spectroscopy; Thickness
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-05034-6

Over the past years, photonic metasurfaces have demonstrated their remarkable and diverse capabilities in advanced control over light propagation. Here, we demonstrate that these artificial films of deeply subwavelength thickness also offer new unparalleled capabilities in decreasing the overall dimensions of integrated optical systems. We propose an original approach of embedding a metasurface inside an optical cavity—one of the most fundamental optical elements—to drastically scale-down its thickness. By modifying the Fabry–Pérot interferometric principle, this methodology is shown to reduce the metasurface-based nanocavity thickness below the conventional
λ
/(2
n
) minimum. In addition, the nanocavities with embedded metasurfaces can support independently tunable resonances at multiple bands. As a proof-of-concept, using nanostructured metasurfaces within 100-nm nanocavities, we experimentally demonstrate high spatial resolution colour filtering and spectral imaging. The proposed approach can be extrapolated to compact integrated optical systems on-a-chip such as VCSEL’s, high-resolution spatial light modulators, imaging spectroscopy systems, and bio-sensors.
Achieving miniature and versatile nanophotonic devices with metasurfaces is of great interest. The authors embed a metasurface inside an optical cavity to reduce thickness and provide degrees of freedom for controlling resonant wavelengths, enabling multi-band filtering, structural colouration and spectral imaging.