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6CCVD Research

Excited-State Lifetime of NV Centers for All-Optical Magnetic Field Sensing

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2024-03-25
JournalSensors
AuthorsLudwig Horsthemke, Jens Pogorzelski, Dennis Stiegekötter, Frederik Hoffmann, Lutz Langguth
InstitutionsQuantum Design (Germany), FH Münster
Citations9
AnalysisFull AI Review Included

Technical Documentation & Analysis: Excited-State Lifetime of NV Centers for All-Optical Magnetic Field Sensing

Section titled “Technical Documentation & Analysis: Excited-State Lifetime of NV Centers for All-Optical Magnetic Field Sensing”

This document analyzes the research paper “Excited-State Lifetime of NV Centers for All-Optical Magnetic Field Sensing” (Sensors 2024, 24, 2093) to provide technical specifications and align the findings with 6CCVD’s advanced MPCVD diamond capabilities.

Executive Summary

Section titled “Executive Summary”
  • Robust Sensing Mechanism: The research successfully demonstrates robust, all-optical magnetic field sensing by utilizing the excited-state fluorescence lifetime (a non-intensity quantity) of high-density Nitrogen-Vacancy (NV) microdiamonds.
  • High Immunity Achieved: The phase-based detection method, measured at an optimal modulation frequency of 13 MHz, yielded a 100-times higher immunity to optical path fluctuations (e.g., laser noise, fiber movement) compared to traditional intensity-based approaches.
  • Material Characteristics: The high-NV-density microdiamond powder exhibited bi-exponential fluorescence decay (6.13 ns and 14.54 ns at B=0), with the larger decay time showing a magnetic contrast of 15.2%.
  • Performance Metrics: A realized noise floor of 20 µT/√Hz was achieved, approaching the calculated shot-noise-limited sensitivity of 0.95 µT/√Hz.
  • Industrial Applicability: The fiber-coupled, microwave (MW)-free setup is compact and operates in a high magnetic field range (10-40 mT), establishing a strong basis for industrial quantum sensing applications where galvanic connections are undesirable.
  • 6CCVD Relevance: The success of this method relies critically on high-quality, high-NV-density diamond material, a core specialty of 6CCVD’s MPCVD growth and processing capabilities.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Material TypeHigh-NV-densityPowderµm-sized microdiamonds
Fluorescence Decay (Short)6.13nsBi-exponential component (τ2,1) at B=0
Fluorescence Decay (Long)14.54nsBi-exponential component (τ2,2) at B=0
Magnetic Contrast (Lifetime)15.2%Contrast observed in the larger decay time (τ2,2)
Optimal Modulation Frequency13MHzFrequency yielding maximum phase contrast
Maximum Phase Contrast5.8°Phase shift at 13 MHz
Excitation Wavelength520nmLaser diode used for frequency domain sensing
Modulation Frequency RangeUp to 100MHzFrequency sweep range
Applied Magnetic Field Range0 to ~120mTRange tested in the experiment
Realized Noise Floor (Phase)20µT/√HzSensitivity achieved above 1 Hz
Shot-Noise-Limited Sensitivity0.95µT/√HzTheoretical limit for phase-based detection
Immunity Improvement100timesPhase-based vs. intensity-based approach
Fiber Core Diameter105µmMultimode fiber used for sensor head

Key Methodologies

Section titled “Key Methodologies”

The experiment utilized two primary measurement techniques: Time-Correlated Single-Photon Counting (TCSPC) for material characterization and Frequency Domain Measurement (FDM) for robust sensing.

  1. Material Preparation: High-NV-density microdiamond powder was fixed to the tip of a 105 µm core optical fiber using glue to create a compact, fiber-coupled sensor head.
  2. TCSPC Characterization: A 515 nm ps-Laser was used to excite the sample. Fluorescence decay histograms were acquired and analyzed using Non-Linear Least Squares (NLLS) fitting, confirming a bi-exponential decay behavior.
  3. Excitation Modulation: A 520 nm laser diode was driven by a constant current source and modulated by an AC-coupled Radio Frequency (RF) amplifier at frequencies up to 100 MHz.
  4. Frequency Domain Acquisition: The fluorescence signal was collected through the same fiber, passed through a long-pass filter, and detected by a Si-photodiode/Trans-Impedance Amplifier (TIA).
  5. Signal Processing: A Vector Network Analyzer (VNA) or a Lock-In Amplifier (LIA) was used to record the magnitude and phase of the fluorescence signal relative to the excitation frequency.
  6. Reference Calibration: Measurements were normalized to the response at B = 0 mT to isolate the magnetic field-dependent change in fluorescence decay dynamics.
  7. Phase-Based Sensing: The LIA was specifically operated at 13 MHz (the frequency of maximum phase contrast) to measure the phase shift (∠Hr), providing inherent immunity to laser intensity noise and optical path fluctuations.

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

The successful implementation of this all-optical magnetometry technique relies on high-quality, high-NV-density diamond material and precise integration capabilities. 6CCVD is uniquely positioned to supply the necessary materials and engineering support to replicate and advance this research toward industrial deployment.

Research Requirement / Challenge6CCVD Solution & CapabilityTechnical Advantage for Quantum Sensing
High-NV Concentration DiamondHigh-Nitrogen Polycrystalline Diamond (PCD) Wafers. We specialize in MPCVD growth with controlled nitrogen incorporation to maximize NV ensemble density.Ensures high fluorescence signal strength (high count rate) necessary to achieve the reported shot-noise-limited sensitivity of 0.95 µT/√Hz.
Custom Sensor GeometryCustom Dimensions & Laser Cutting. We provide PCD plates up to 125 mm and SCD plates in thicknesses ranging from 0.1 µm to 500 µm, cut to precise dimensions for fiber integration.Enables the fabrication of compact, reproducible sensor heads optimized for coupling to 105 µm core fibers or micro-optics, moving beyond powder/glue methods.
Surface Quality for Optical CouplingUltra-Low Roughness Polishing. We offer polishing services achieving Ra < 5 nm for inch-size PCD and Ra < 1 nm for SCD.Minimizes scattering and reflection losses at the diamond-fiber interface, maximizing the efficiency of both 520 nm excitation and fluorescence collection.
Robust Integration & Heat ManagementCustom Metalization Services. We provide in-house deposition of standard metal stacks (e.g., Ti/Pt/Au, W/Cu) for robust bonding, thermal management, or creating electrical contacts.Ensures reliable, high-adhesion interfaces for permanent integration into industrial probes, mitigating thermal drift that could affect optical alignment.
Replication and OptimizationExpert Engineering Support. Our in-house PhD team assists with material selection, NV creation recipes (e.g., optimizing annealing parameters), and thickness selection for specific decay dynamics.Accelerates R&D for engineers seeking to tune the bi-exponential decay components or explore alternative materials like Boron-Doped Diamond (BDD) for electrochemistry applications.
Global Supply ChainGlobal Shipping (DDU/DDP). We ensure reliable, worldwide delivery of sensitive diamond materials.Guarantees timely access to critical quantum materials, supporting international research collaborations and industrial prototyping.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

We investigate the magnetic field-dependent fluorescence lifetime of microdiamond powder containing a high density of nitrogen-vacancy centers. This constitutes a non-intensity quantity for robust, all-optical magnetic field sensing. We propose a fiber-based setup in which the excitation intensity is modulated in a frequency range up to 100MHz. The change in magnitude and phase of the fluorescence relative to B=0 is recorded where the phase shows a maximum in magnetic contrast of 5.8∘ at 13MHz. A lock-in amplifier-based setup utilizing the change in phase at this frequency shows a 100 times higher immunity to fluctuations in the optical path compared to the intensity-based approach. A noise floor of 20μT/Hz and a shot-noise-limited sensitivity of 0.95μT/Hz were determined.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2020 - Sensitivity optimization for NV-diamond magnetometry [Crossref]
  2. 2021 - A hybrid magnetometer towards femtotesla sensitivity under ambient conditions [Crossref]
  3. 2012 - Magnetic-field-dependent photodynamics of single NV defects in diamond: An application to qualitative all-optical magnetic imaging [Crossref]
  4. 2017 - Scanning diamond NV center probes compatible with conventional AFM technology [Crossref]
  5. 2009 - Time-averaging within the excited state of the nitrogen-vacancy centre in diamond [Crossref]
  6. 2020 - Isotropic Scalar Quantum Sensing of Magnetic Fields for Industrial Application [Crossref]
  7. 2014 - Fiber-optic magnetic-field imaging [Crossref]
  8. 2021 - All-optical and microwave-free detection of Meissner screening using nitrogen-vacancy centers in diamond [Crossref]
  9. 2015 - Low-field feature in the magnetic spectra of N-V centers in diamond [Crossref]
  10. 2016 - Microwave-free magnetometry with nitrogen-vacancy centers in diamond [Crossref]

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