Nanoelectromechanical spectral control of silicon bowtie nanocavities for quantum light sources

TL;DR

This paper introduces a tunable silicon bowtie nanocavity with strong light confinement, achieved through nanoelectromechanical actuation, enabling efficient quantum light sources with minimal power and reversible spectral tuning.

Contribution

It presents the first low-loss dielectric tunable bowtie nanocavity with strong confinement and weak voltage dependence, advancing quantum photonic technology.

Findings

Purcell factor above 6,500 achieved

Waveguide-coupling efficiency exceeds 30%

Spectral tuning range of 11 nm with reversible control

Abstract

We present the design, fabrication, and characterization of tunable waveguide-coupled silicon bowtie cavities with strong spatial electromagnetic field confinement. We use nanoelectromechanical in-plane actuation for the tuning, as this combines cryocompatibility with an ultralow power consumption. Our device leverages a mode volume below 0.2 cubic wavelengths in the material to reach theoretical Purcell factors above 6,500 and waveguide-coupling efficiency above 30% across the full experimentally measured spectral-tuning range of 11 nm. Notably, the Purcell factor in our cavity depends only weakly on the applied voltage. Our spectral measurements demonstrate reversible tuning of bowtie cavities, and we directly show the in-plane actuation using in-situ characterization in a scanning electron microscope. Our results constitute the first demonstration of a low-loss dielectric tunable bowtie nanocavity with strong light confinement. This solves a key issue for experiments on strong light-matter interactions for cavity quantum electrodynamics and scalable photonic quantum technologies.