Temperature Fluctuations Compensation with Multi-Frequency Synchronous Manipulation for a NV Magnetometer in Fiber-Optic Scheme

At a Glance

Metadata	Details
Publication Date	2022-07-12
Journal	Sensors
Authors	Ning Zhang, Qiang Guo, Wen Ye, Rui Feng, Heng Yuan
Institutions	Zhejiang Lab, Beihang University
Citations	3
Analysis	Full AI Review Included

Executive Summary

This research details the development and validation of a highly stable, miniaturized nitrogen-vacancy (NV) center magnetometer in a fiber-optic scheme, focusing on compensating for temperature-induced measurement drift.

Core Value Proposition: A robust, portable NV magnetometer that achieves effective temperature compensation without requiring external thermal control equipment, crucial for micro-magnetic field and biological sensing applications.
Key Methodology: A Multi-Frequency Synchronous Manipulation (MFSM) scheme was implemented, leveraging the differential response of the ODMR spectrum to magnetic fields versus the common-mode response to temperature fluctuations.
Thermal Stability Achievement: MFSM reduced the fluorescence signal fluctuations caused by temperature changes (within a ±2 °C range) from 5.5% (using single-frequency manipulation) down to 1.0%.
Performance Improvement: The omnidirectional MFSM scheme maximized the number of participating NV centers, resulting in a 44.7% improvement in the Signal-to-Noise Ratio (SNR) for magnetic field measurement compared to single-frequency methods.
Material Characterization: The temperature dependence of the Zero-Field Splitting (ZFS) energy D was characterized, yielding linear shift rates near room temperature of -70.2 kHz/K for HTHP diamond particles and -67.9 kHz/K for bulk CVD diamond.
System Noise Floor: The remaining 1.0% fluorescence noise after compensation is attributed to non-thermal factors (e.g., laser power fluctuations, detector noise), establishing the system’s current noise floor.

Technical Specifications

Parameter	Value	Unit	Context
Sensor Scheme	Fiber-Optic	N/A	Miniaturized NV magnetometer
Diamond Type (Sensor)	HTHP (High-Concentration)	N/A	Used as diamond particle sensor head
Diamond Particle Diameter	~300	µm	Size of diamond adhered to fiber tip
HTHP Irradiation Dose	1 x 10¹⁸	e^-/cm²	Electron irradiation for NV creation
HTHP Annealing Temperature	800	°C	Post-irradiation treatment
CVD N Concentration (Original)	800	ppb	Bulk diamond sample for comparison
CVD Irradiation Dose	5 x 10¹⁷	e^-/cm²	Electron irradiation for NV creation
Excitation Laser Wavelength	532	nm	Pulsed modulation via AOM
Microwave Coil Material	Gold Wire	N/A	Diameter 100 µm, wound spirally
Temperature Range (Compensation Test)	±2	°C	Range compensated by MFSM
HTHP ZFS Shift Rate (240-300 K)	-70.2	kHz/K	Linear temperature sensitivity
CVD ZFS Shift Rate (240-300 K)	-67.9	kHz/K	Linear temperature sensitivity
Fluorescence Noise (Single-Freq)	5.5	%	Fluctuation rate before compensation
Fluorescence Noise (Multi-Freq)	1.0	%	Fluctuation rate after compensation
SNR Improvement (MFSM)	44.7	%	Gain over single-frequency manipulation
Microwave Modulation Frequency	0.1	Hz	Used for magnetic field sensing
Microwave Modulation Amplitude	1	MHz	Used for magnetic field sensing

Key Methodologies

Sensor Head Fabrication: A high-concentration HTHP diamond particle (~300 µm) was adhered to a multimode fiber tip. A 100 µm gold wire was tightly wound into a spiral around the fiber tip to serve as a compact microwave resonator.
Temperature Dependence Calibration: ODMR experiments were conducted using a liquid nitrogen thermostat (80-300 K) to extract the ZFS energy D shift as a function of temperature for both HTHP particles and bulk CVD diamond.
System Thermal Noise Quantification: ODMR experiments were performed while scanning the input microwave power (up to 10 dBm) to measure the resulting shift in the NV resonance frequency, confirming that increased microwave power generates a thermal effect (negative correlation with resonance frequency).
Bias Field Alignment: A bias magnetic field was applied in the [111] direction to separate the NV centers into two symmetry groups (non-[111] and [111] directions) in the ODMR spectrum, facilitating vector magnetic field measurement.
Dual-Frequency Compensation (MFSM Principle): The NV centers were simultaneously manipulated at two symmetrical frequency points (f_a and f_b) on the resonance line slopes. Since temperature shifts cause both frequencies to move in the same direction (canceling the fluorescence change), while magnetic fields cause them to move oppositely (maximizing the differential signal), temperature fluctuations are effectively suppressed.
Omnidirectional MFSM Implementation: The compensation scheme was extended to four frequencies corresponding to the NV centers in all four crystal lattice directions, maximizing the fluorescence contrast and improving the overall measurement SNR.

Commercial Applications

Miniaturized Quantum Sensing: Enabling the creation of highly stable, portable, and compact quantum magnetometers for field deployment and non-laboratory environments.
Biomagnetism and Intracellular Measurement: Use in biological sensing, including intracellular measurement and electromagnetic imaging, where the small size and non-metallic nature of the fiber sensor are critical.
Vector Magnetic Field Sensing: Applications requiring high-resolution measurement of magnetic field components in multiple axes simultaneously, leveraging the omnidirectional manipulation scheme.
Industrial Process Monitoring: Stable magnetic sensing in environments subject to significant temperature fluctuations (e.g., industrial machinery, high-power RF systems) where traditional sensors struggle with thermal drift.
Quantum Metrology: Improving the stability and precision of fundamental measurement standards based on solid-state quantum defects.

View Original Abstract

Nitrogen-vacancy (NV) centers in diamonds play a large role in advanced quantum sensing with solid-state spins for potential miniaturized and portable application scenarios. With the temperature sensitivity of NV centers, the temperature fluctuations caused by the unknown environment and the system itself will mix with the magnetic field measurement. In this research, the temperature-sensitive characteristics of different diamonds, alongside the temperature noise generated by a measurement system, were tested and analyzed with a homemade NV magnetometer in a fiber-optic scheme. In this work, a multi-frequency synchronous manipulation method for resonating with the NV centers in all axial directions was proposed to compensate for the temperature fluctuations in a fibered NV magnetic field sensing scheme. The symmetrical features of the resonance lines of the NV centers, the common-mode fluctuations including temperature fluctuations, underwent effective compensation and elimination. The fluorescence change was reduced to 1.0% by multi-frequency synchronous manipulation from 5.5% of the single-frequency manipulation within a ±2 °C temperature range. Additionally, the multi-frequency synchronous manipulation improved the fluorescence contrast and the magnetic field measurement SNR through an omnidirectional manipulation scheme. It was very important to compensate for the temperature fluctuations, caused by both internal and external factors, to make use of the NV magnetometer in fiber-optic schemes’ practicality. This work will promote the rapid development and widespread applications of quantum sensing based on various systems and principles.

Tech Support

Original Source

DOI: https://doi.org/10.3390/s22145218

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