Stimulated Emission Depletion Microscopy with Color Centers in Hexagonal Boron Nitride

TL;DR

This paper demonstrates super-resolution STED microscopy using color centers in hexagonal boron nitride, achieving ~50 nm resolution and predicting potential for sub-10 nm resolution with improved optics.

Contribution

It introduces a novel application of STED microscopy with hBN color centers, achieving nanoscale resolution and outlining future improvements.

Findings

Achieved ~50 nm resolution with hBN color centers.

Resolved two color centers separated by 250 nm.

Predicted sub-10 nm resolution possible with better optics.

Abstract

Stimulated emission depletion, or STED microscopy is a well-established super-resolution technique, but is ultimately limited by the chosen flourophore. Here we demonstrate STED microscopy with color centers in nanoscale flakes of hexagonal boron nitride using time-gated continuous wave STED. For color centers with zero phonon line emission around 580 nm we measure a STED cross-section of (5.5 $\pm$ 3.2) x $10^{-17} \mbox{cm}^{2}$, achieve a resolution of $\sim$ 50 nm and resolve two color centers separated by 250 nm, which is less than the diffraction limit. The achieved resolution is limited by the numerical aperture of the objective lens (0.8) and the available laser power, and we predict that a resolution of sub-10 nm can be achieved with an oil immersion objective lens, similar to state-of-the-art resolution obtained with nitrogen vacancy centers in diamond.