Wide bandwidth instantaneous RF spectrum analyzer based on nitrogen vacancy centers in diamond

TL;DR

This paper introduces a novel optical method using nitrogen-vacancy centers in diamond for real-time, wide-bandwidth microwave spectrum analysis with high spatial and frequency resolution, suitable for various magnetic field conditions.

Contribution

The authors develop an innovative analog technique leveraging NV centers in diamond for instantaneous, wide-band microwave spectral analysis with high spatial and frequency resolution.

Findings

Achieved 600 MHz bandwidth with 7 MHz resolution.

Demonstrated 4 ms refresh rate for spectral analysis.

Potential to extend frequency range to 30 GHz.

Abstract

We propose an original analog method to perform instantaneous and quantitative spectral analysis of microwave signals. An ensemble of nitrogen-vacancy (NV) centers held in a diamond plate is pumped by a 532 nm laser. Its photoluminescence is imaged through an optical microscope and monitored by a digital camera. The microwave signal is converted to an oscillating magnetic field in the area of the NV centers by a loop shaped antenna. Induced magnetic resonances are detected through a decrease of the NV centers photoluminescence. A magnetic field gradient induces a Zeeman shift of the resonances and transforms the frequency information into spatial information, which allows for the simultaneous analysis of the microwave signal in the entire frequency bandwidth of the device. The time dependent spectral analysis of an amplitude modulated microwave signal is demonstrated over a bandwidth of 600 MHz, associated to a frequency resolution of 7 MHz and a refresh rate of 4 ms. With such integration time, a field of a few hundreds of {\mu}W can be detected. Since the optical properties of NV centers can be maintained even in high magnetic field, we estimate that an optimized device could allow frequency analysis in a range of 30 GHz, only limited by the amplitude of the magnetic field gradient. In addition, an increase of the NV centers quantity could lead both to an increase of the microwave sensitivity and to a decrease of the minimum refresh rate down to a few {\mu}s.