# Optical detection of paramagnetic defects in diamond using off-resonance excitation of NV centers

## TL;DR

This paper introduces a novel optical method to detect paramagnetic defects in diamond, like P1 centers, using off-resonance excitation of NV centers, enabling detection across a wide range of magnetic fields and frequencies.

## Contribution

It presents a new off-resonance optical detection technique for paramagnetic defects in diamond, expanding the capabilities beyond traditional magnetic resonance methods.

## Key findings

- Successful detection of P1 defects via off-resonance NV fluorescence
- Good agreement between experimental data and theoretical models
- Potential for biological imaging applications using defect detection

## Abstract

In this work we use fluorescence from nitrogen-vacancy defects in diamond to detect and explore other paramagnetic defects in the diamond, such as P1 defects, which are commonly undetectable through optical detection of magnetic resonance in standard conditions. Our method does not require overlap between the defects' resonances and therefore is applicable in a wide region of magnetic fields and frequencies, as verified by excellent fit to theoretical predictions. We propose a depolarization scheme of P1 defects to account for the observed data. To verify our results, we perform cavity-based detection of magnetic resonance and find a good agreement between the measured optically induced polarization and the value obtained theoretically from rate equations. The findings in this work may open the way to detection of paramagnetic defects outside of the diamond through the photoluminesence of nitrogen-vacancy defects, which might be useful for imaging in biology.