Microsphere-assisted generation of localized optical emitters in 2D hexagonal boron nitride

TL;DR

This paper introduces a microsphere-assisted technique to precisely generate and enhance optical emitters in hexagonal boron nitride, significantly improving localization and fluorescence collection for quantum and sensing applications.

Contribution

The study presents a novel microsphere-based method that improves defect placement accuracy and optical signal collection in hBN, advancing nanoscale quantum emitter engineering.

Findings

Reduced emission area by a factor of 5

Enhanced fluorescence collection efficiency by ~10 times

Demonstrated improved defect generation and optical readout

Abstract

Crystal defects in hexagonal boron nitride (hBN) are emerging as versatile nanoscale optical probes with a wide application profile, spanning the fields of nanophotonics, biosensing, bioimaging and quantum information processing. However, generating these crystal defects as reliable optical emitters remains challenging due to the need for deterministic defect placement and precise control of the emission area. Here, we demonstrate an approach that integrates microspheres (MS) with hBN optical probes to enhance both defect generation and optical signal readout. This technique harnesses MS to amplify light-matter interactions at the nanoscale through 2 two mechanisms: focused femtosecond (fs) laser irradiation into a photonic nanojet for highly localized defect generation, and enhanced light collection via the whispering gallery mode effect. Our MS-assisted defect generation method reduces the emission area by a factor of 5 and increases the fluorescence collection efficiency by approximately 10 times compared to MS-free samples. These advancements in defect generation precision and signal collection efficiency open new possibilities for optical emitter manipulation in hBN, with potential applications in quantum technologies and nanoscale sensing.