Ultrathin and Multicolor Optical Cavities with Embedded Metasurfaces

TL;DR

This paper introduces a novel method of embedding metasurfaces inside optical cavities to create ultrathin, multicolor nano-cavities capable of high-resolution spectral filtering and imaging, significantly reducing device size.

Contribution

It proposes and experimentally demonstrates a new approach to drastically miniaturize optical cavities using embedded metasurfaces, enabling multi-band tunable resonances.

Findings

Achieved cavity thickness below half-wavelength using embedded metasurfaces.

Demonstrated high-resolution color filtering and spectral imaging.

Enabled multi-band tunable resonances in nano-cavities.

Abstract

Over the past years, photonic metasurfaces have demonstrated their remarkable and diverse capabilities for achieving advanced control over light propagation by confining electromagnetic radiation within the deeply subwavelength thickness of these artificial films. Here, we demonstrate that metasurfaces also offer new unparalleled capabilities for decreasing the overall dimensions of integrated optical components and systems. We propose an original approach of embedding a metasurface inside one of the most fundamental optical elements -an optical cavity- to drastically scale-down the thickness of the optical cavity. We apply this methodology to design and implement a metasurfaces-based nano-cavity where the Fabry-Perot interferometric principle has been modified to reduce the cavity thickness below the conventional half-wavelength minimum. In addition, the nano-cavities with embedded metasurfaces can support independently tunable resonances at multiple bands. As a proof-of-concept, using nano-structured metasurfaces within 100-nm nano-cavities, we experimentally demonstrate high spatial resolution color filtering and spectral imaging. The proposed approach can be extrapolated to compact integrated optical systems on-a-chip such as VCSEL, high-resolution spatial light modulators, imaging spectroscopy systems, and bio-sensors.