Tuning of Silicon Nitride Micro Cavities by Controlled Nanolayer Deposition

TL;DR

This paper presents a novel method for tuning silicon nitride microcavities using controlled nanolayer deposition and laser heating, enabling precise resonance matching for quantum photonic applications.

Contribution

The authors introduce a new nanolayer deposition technique combined with laser heating for effective cavity tuning without degrading quality factors.

Findings

Resonance tuning over a free spectral range achieved

Quality factor remains unaffected by nanolayer deposition

Cladding deposition does not displace nanoparticles on the cavity

Abstract

Integration of single-photon emitters (SPEs) with resonant photonic structures is a promising approach for realizing compact and efficient single-photon sources for quantum communications, computing, and sensing. Efficient interaction between the SPE and the photonic cavity requires that the cavity's resonance matches the SPE emission line. Here we demonstrate a new method for tuning silicon nitride (Si3N4) microring cavities via controlled deposition of the cladding layers. Guided by numerical simulations, we deposit silicon dioxide (SiO2) nanolayers onto Si3N4 ridge structures in steps of 50 nm. We show tuning of the cavity resonance over a free spectral range (FSR) without degradation of the quality-factor (Q-factor) of the cavity. We then complement this method with localized laser heating for fine-tuning of the cavity. Finally, we verify that the cladding deposition does not alter the position of nanoparticles placed on the cavity, which suggests that our method can be useful for integrating SPEs with photonic structures.