Post-fabrication tuning of circular Bragg resonators for enhanced emitter-cavity coupling

TL;DR

This paper presents a post-fabrication chemical etching method to tune the spectral properties of circular Bragg resonators, significantly improving emitter-cavity coupling and emission enhancement in solid-state quantum emitters.

Contribution

It introduces a novel post-fabrication tuning technique for circular Bragg resonators, enabling spectral alignment and enhanced emitter-cavity coupling after fabrication.

Findings

Achieved ~16 nm wavelength tuning of optical modes.

Demonstrated 4-fold Purcell enhancement of quantum dot emission.

Numerical models confirm the robustness of the tuning method.

Abstract

Solid-state quantum emitters embedded in circular Bragg resonators are attractive due to their ability to emit quantum states of light with high brightness and low multi-photon probability. As for any emitter-microcavity system, fabrication imperfections limit the spatial and spectral overlap of the emitter with the cavity mode, thus limiting their coupling strength. Here, we show that an initial spectral mismatch can be corrected after device fabrication by repeated wet chemical etching steps. We demonstrate ~16 nm wavelength tuning for optical modes in AlGaAs resonators on oxide, leading to a 4-fold Purcell enhancement of the emission of single embedded GaAs quantum dots. Numerical calculations reproduce the observations and suggest that the achievable performance of the resonator is only marginally affected in the explored tuning range. We expect the method to be applicable also to circular Bragg resonators based on other material platforms, thus increasing the device yield of cavity-enhanced solid-state quantum emitters.