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6CCVD Research

All Fiber Vector Magnetometer Based on Nitrogen-Vacancy Center

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2023-03-06
JournalNanomaterials
AuthorsMan Zhao, Qijing Lin, Qingzhi Meng, Wenjun Shan, Liangquan Zhu
InstitutionsYantai University, Xi’an Jiaotong University
Citations14
AnalysisFull AI Review Included

All Fiber Vector Magnetometer Based on Nitrogen-Vacancy Center: Technical Analysis and 6CCVD Solutions

Section titled “All Fiber Vector Magnetometer Based on Nitrogen-Vacancy Center: Technical Analysis and 6CCVD Solutions”

Executive Summary

Section titled “Executive Summary”

This research successfully demonstrates a compact, robust, and portable all-fiber nitrogen-vacancy (NV) center vector magnetometer, replacing bulky spatial optics with multi-mode fiber components. This advancement is critical for industrial applications, magnetic endoscopy, and remote sensing.

  • Performance Benchmark: Achieved a photon shot-noise limited sensitivity of 0.73 nT/Hz1/2, demonstrating feasibility comparable to conventional confocal systems.
  • Optical Efficiency: The all-fiber system delivered 1.87 times higher fluorescence intensity compared to the traditional confocal setup, resulting in a 27% sensitivity improvement over the theoretical confocal limit.
  • Material Requirements: The system relies on high-quality Type-Ib HPHT micro-diamond (550 ”m diameter) with a high NV ensemble density of approximately 1.08 x 1018 cm-3.
  • Key Innovation: Utilizes a Wideband Multi-mode Circulator (WMC) to efficiently separate the 532 nm excitation laser from the 600-800 nm NV fluorescence, achieving ten times higher optical transmission efficiency than standard 1 x 2 fiber couplers.
  • Vector Detection: A simplified, rapid vector magnetic field measurement method was proposed, enabling ”m-scale detection by aligning the diamond’s <111> crystal axis with the optical fiber.
  • Application Potential: The robust, anti-interference nature of the fiber system promotes practical use in complex physical environments (high temperature, high pressure) for magnetic field imaging and sensing.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Magnetometer Sensitivity (All-Fiber)0.73nT/Hz1/2Photon shot-noise limited performance
Diamond Material TypeType-Ib HPHTN/APrecursor material for NV creation
Diamond Dimension (Axial, zd)550”mMicro-diamond diameter
NV Center Density (N0)1.08 x 1018cm-3Achieved post-irradiation and annealing
Excitation Laser Wavelength532nmUsed for pulsed ODMR
Fluorescence Wavelength Range600-800nmNV center emission spectrum
Laser Power Transmitted (Plaser)64.2mWPower reaching the diamond (64.2% efficiency)
Fiber Core Diameter200”mMulti-mode fiber used for excitation/collection
Fiber Numerical Aperture (NA1)0.39N/ANumerical aperture of Port 2 fiber
Fluorescence Collection Efficiency (Fiber)0.607%Theoretical estimate
Zero-Field Splitting (D)2871.5MHzMeasured from zero magnetic field ODMR
Lattice Stress Parameter (E)3.5MHzMeasured from zero magnetic field ODMR

Key Methodologies

Section titled “Key Methodologies”

The all-fiber vector magnetometer relies on precise material preparation and advanced optical integration:

  1. Diamond Selection and Preparation: A Type-Ib HPHT micro-diamond (550 ”m diameter, cubo-octahedron morphology) was selected.
  2. NV Center Creation: The diamond was irradiated using a 10 MeV electron beam at a dose of 1 x 1018 cm-2, followed by two-step annealing (850 °C in vacuum, then 500 °C in air) to achieve the target NV density (N0 ≈ 1.08 x 1018 cm-3).
  3. Fiber Integration and Alignment: The diamond was glued to the tip of a multi-mode fiber (200 ”m core) using ethyl cyanoacrylate. Crucially, a hexagon surface corresponding to the <111> crystal plane was aligned to coincide with the axial direction of the optical fiber.
  4. Optical Interrogation System: A 532 nm laser was pulsed via an Acousto-Optic Modulator (AOM) and routed through a Wideband Multi-mode Circulator (WMC). The WMC effectively separated the excitation laser (Port 1 to 2) from the red-shifted NV fluorescence (Port 2 to 3), replacing the traditional dichroic mirror.
  5. Spin Manipulation: An eight-turn copper coil antenna was wound around the ceramic ferrule near the diamond tip to deliver the microwave (MW) signals necessary for pulsed Optically Detected Magnetic Resonance (ODMR).
  6. Vector Field Measurement: A simplified method was used: a single-axis Helmholtz coil generated an auxiliary calibration field (Ba). By measuring the ODMR spectra under Ba, the measured field Bm, and the superimposed field Ba + Bm, the magnitude and direction of the vector magnetic field Bm were rapidly extracted.

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

6CCVD provides the high-specification MPCVD diamond materials and customization services required to replicate, optimize, and scale this advanced all-fiber NV magnetometry research.

Research Requirement (Paper)6CCVD Solution & CapabilityTechnical Advantage
High-Quality Diamond PrecursorOptical Grade Single Crystal Diamond (SCD) or High-Density Polycrystalline Diamond (PCD)Our MPCVD growth process yields ultra-low strain and low intrinsic nitrogen content, providing the ideal platform for controlled, high-yield NV center creation (N0 > 1018 cm-3).
Custom Dimensions & MorphologyCustom Sizing, Dicing, and Laser CuttingThe paper required a 550 ”m diameter micro-diamond. 6CCVD offers precise laser cutting and dicing services on SCD and PCD wafers (up to 125mm) to achieve specific geometries required for fiber coupling.
Precise Surface PreparationUltra-Low Roughness PolishingWe guarantee surface roughness Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD. This ensures atomically flat surfaces necessary for reliable, high-precision gluing and alignment of the critical <111> crystal plane to the fiber tip.
Integrated Microwave DeliveryIn-House Custom MetalizationWhile the paper used a wound copper coil, 6CCVD can deposit thin-film metal layers (Au, Pt, Ti, W, Cu) directly onto the diamond substrate. This allows for the fabrication of integrated stripline or loop antennas, improving MW field uniformity and delivery efficiency for enhanced ODMR contrast.
Material Thickness ControlSCD/PCD Thickness Control (0.1 ”m to 500 ”m)We provide precise control over the diamond thickness, allowing researchers to optimize the active NV volume for maximum fluorescence collection efficiency in fiber-coupled systems.
Global LogisticsGlobal Shipping (DDU/DDP)We ensure rapid and reliable delivery of custom diamond substrates worldwide, simplifying the procurement process for international research teams.

Engineering Support: 6CCVD’s in-house team of PhD material scientists specializes in optimizing MPCVD growth parameters to meet specific NV center requirements, including precursor material selection for subsequent high-dose irradiation and annealing protocols. We provide consultation on material specifications to maximize sensitivity for similar magnetic endoscopy and remote sensing projects.

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

View Original Abstract

Magnetometers based on nitrogen-vacancy (NV) centers in diamonds have promising applications in fields of living systems biology, condensed matter physics, and industry. This paper proposes a portable and flexible all-fiber NV center vector magnetometer by using fibers to substitute all conventional spatial optical elements, realizing laser excitation and fluorescence collection of micro-diamond with multi-mode fibers simultaneously and efficiently. An optical model is established to investigate multi-mode fiber interrogation of micro-diamond to estimate the optical performance of NV center system. A new analysis method is proposed to extract the magnitude and direction of the magnetic field, combining the morphology of the micro-diamond, thus realizing ÎŒm-scale vector magnetic field detection at the tip of the fiber probe. Experimental testing shows our fabricated magnetometer has a sensitivity of 0.73 nT/Hz1/2, demonstrating its feasibility and performance in comparison with conventional confocal NV center magnetometers. This research presents a robust and compact magnetic endoscopy and remote-magnetic measurement approach, which will substantially promote the practical application of magnetometers based on NV centers.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2006 - Coherent dynamics of coupled electron and nuclear spin qubits in diamond [Crossref]
  2. 2017 - Quantum sensing [Crossref]
  3. 2006 - Room-temperature coherent coupling of single spins in diamond [Crossref]
  4. 2018 - High-resolution magnetic resonance spectroscopy using a solid-state spin sensor [Crossref]
  5. 2020 - A Modified Spin Pulsed Readout Method for NV Center Ensembles Reducing Optical Noise [Crossref]
  6. 2019 - Microwave Field Uniformity Impact on DC Magnetic Sensing With NV Ensembles in Diamond [Crossref]
  7. 2013 - Optical magnetic imaging of living cells [Crossref]
  8. 2012 - High spatial and temporal resolution wide-field imaging of neuron activity using quantum NV-diamond [Crossref]
  9. 2018 - Magnetic imaging of a single ferromagnetic nanowire using diamond atomic sensors [Crossref]
  10. 2020 - Imaging viscous flow of the Dirac fluid in graphene [Crossref]

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