Nanoelectromechanical Spectral Control of Silicon Bowtie Nanocavities for Quantum Light Sources

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 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. 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 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.