Efficient nitrogen-vacancy centers' fluorescence excitation and collection from micrometer-sized diamond by a tapered optical fiber

TL;DR

This paper introduces a tapered optical fiber tip that significantly enhances the excitation and collection efficiency of fluorescence from nitrogen-vacancy centers in diamond, improving the sensitivity of fiber-optic NV sensors.

Contribution

The study demonstrates a novel tapered optical fiber design that greatly increases fluorescence excitation and collection efficiency for NV centers, advancing fiber-optic diamond sensor technology.

Findings

Over 7-fold increase in fluorescence excitation efficiency

Over 15-fold increase in fluorescence collection efficiency

Enhanced sensitivity of fiber-optic diamond magnetometers

Abstract

Efficiently excite nitrogen-vacancy (NV) centers in diamond and collect their fluorescence significantly benefit the fiber-optic-based NV sensors. Here, using a tapered optical fiber (TOF) tip, we significantly improve the efficiency of the laser excitation and fluorescence collection of the NV, thus enhance the sensitivity of the fiber-optic based micron-sized diamond magnetic sensor. Numerical calculation shows that the TOF tip delivers a high numerical aperture (NA) and has a high fluorescence excitation and collection efficiency. Experiments demonstrate that using such TOF tip can obtain up to over 7-fold the fluorescence excitation efficiency and over15-fold the fluorescence collection efficiency of a flat-ended (non-TOF) fiber. Such fluorescence collection enhances the sensitivity of the optical fiber-based diamond NV magnetometer, thus extending its potential application region.