Nanoscale resolved mapping of the dipole emission of hBN color centers with a scattering-type scanning near-field optical microscope

TL;DR

This paper employs scattering-type near-field optical microscopy to map and analyze the nanoscale emission properties of hBN color centers, advancing quantum light source characterization.

Contribution

It introduces a novel application of s-SNOM for nanoscale mapping of dipole orientations and emission characteristics of hBN quantum emitters.

Findings

Demonstrated sub-diffraction limited tip-enhanced PL hotspot.

Showed increased PL intensity via tip-assisted scattering.

Mapped in-plane dipole orientations of hBN color centers.

Abstract

Color centers in hexagonal boron nitride (hBN) are promising candidates as quantum light sources for future technologies. In this work, we utilize a scattering-type near-field optical microscope (s-SNOM) to study the photoluminescence (PL) emission characteristics of such quantum emitters in metalorganic vapor phase epitaxy grown hBN. On the one hand, we demonstrate direct near-field optical excitation and emission through interaction with the nanofocus of the tip resulting in a sub-diffraction limited tip-enhanced PL hotspot. On the other hand, we show that indirect excitation and emission via scattering from the tip significantly increases the recorded PL intensity. This demonstrates that the tip-assisted PL (TAPL) process efficiently guides the generated light to the detector. We apply the TAPL method to map the in-plane dipole orientations of the hBN color centers on the nanoscale. This work promotes the widely available s-SNOM approach to applications in the quantum domain including characterization and optical control.