Enhanced Tunable Photon Pair Generation from Nonlinear Metasurface with Guided-Mode Cavity

TL;DR

This paper demonstrates a nonlinear metasurface with a guided-mode cavity that significantly enhances photon pair generation rates and allows tunable emission directions, advancing quantum light source technology.

Contribution

It introduces a novel nonlinear metasurface with a guided-mode cavity that achieves substantial SPDC rate enhancement and tunable photon emission directions.

Findings

SPDC rate up to 157 Hz/mW with cavity

30 times rate enhancement over non-cavity metasurface

Broadband high-Q resonances enable all-optical tuning

Abstract

The ability to generate quantum entangled photon pairs through spontaneous parametric down conversion (SPDC) is playing a pivotal role in many applications in quantum technologies, including quantum communications, quantum computation, and quantum imaging. Metasurfaces, two-dimensional arrays of nanostructures with subwavelength thickness, have recently shown extraordinary capability in manipulating classical and quantum states of light and realizing miniaturized SPDC sources. Whereas previous studies have primarily focused on periodic metasurfaces, we uncover the potential of spatially modulated nanopatterns for further SPDC enhancement and state engineering. Specifically, we propose a nonlinear metasurface featuring a lateral guided-mode cavity formed by two distributed Bragg reflectors. With the quasi-normal mode theory, we predict an SPDC rate up to 157 Hz/mW, which represents about 30 times rate enhancement when compared to the metasurface without a cavity. Furthermore, the cavity supports a continuous set of high-Q resonances across a broad bandwidth, allowing the all-optical tuning of the photon-pair emission directions transverse to the cavity by controlling the pump wavelength, which can find applications in quantum imaging.