Fluorescent diamond microparticle doped glass fiber for magnetic field sensing
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-08-01 |
| Journal | APL Materials |
| Authors | D Bai, M. H. Huynh, D. A. Simpson, P. Reineck, S. A. Vahid |
| Institutions | University of South Australia, RMIT University |
| Citations | 37 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Fluorescent Diamond Microparticles for Magnetic Field Sensing
Section titled âTechnical Documentation & Analysis: Fluorescent Diamond Microparticles for Magnetic Field SensingâThis document analyzes the research on integrating NV-diamond microparticles into optical fibers for remote magnetometry, highlighting how 6CCVDâs advanced MPCVD diamond materials and customization capabilities can support and extend this critical quantum technology research.
Executive Summary
Section titled âExecutive Summaryâ- Application Focus: Development of a robust, field-deployable fiber-optic platform for high-sensitivity magnetic field sensing using ensemble Nitrogen-Vacancy (NV) centers in diamond.
- Performance Achieved: Demonstrated enhanced room-temperature DC magnetic field sensitivity, achieving 350 nT/âHz for localized sensing and ~3 ”T/âHz for remote sensing over a 50 cm fiber length.
- Material Strategy: Utilized micron-sized (~1 ”m) diamond particles, which offer four orders of magnitude higher NV center density compared to previously used nanodiamonds (NDs, ~45 nm), significantly boosting sensitivity.
- Fabrication Innovation: Employed a novel interface doping technique (cane-in-tube approach) using high-viscosity F2 lead-silicate glass, spatially confining the microdiamonds to an annular interface.
- Material Preservation: The high viscosity (~106 dPa·s) of the F2 glass during fiber drawing prevented chemical dissolution of the diamond particles, preserving the NV center fluorescence and spin properties.
- Optical Improvement: The interface doping geometry resulted in a lower fiber propagation loss (~4 dB/m) compared to previous volume-doped fibers (~10 dB/m), improving fluorescence collection efficiency for remote readout.
- Future Direction: Results emphasize the need for high-purity diamond materials with controlled nitrogen/carbon isotopes and optimized fiber structures (step-index core/clad) to further enhance sensitivity for quantum metrology.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Particle Size (Dopant) | ~1 | ”m | Microdiamond (MSY 0.75-1.25) |
| Estimated NV Center Concentration | ~1 | ppm | In diamond particles |
| Best DC Magnetic Field Sensitivity | 350 | nT/âHz | Localized (side/side) scheme, room temperature |
| Remote DC Magnetic Field Sensitivity | ~3 | ”T/âHz | Longitudinal (end/end) scheme, 50 cm fiber length |
| Fiber Outer Diameter (OD) | ~130 | ”m | Drawn F2/F2 fiber |
| Inner/Outer Interface Diameter | ~9 | ”m | Location of diamond particle confinement |
| Propagation Loss (532 nm Excitation) | ~4.6 | dB/m | Diamond-doped F2/F2 fiber |
| Propagation Loss (600-800 nm Emission) | ~4.0 | dB/m | Diamond-doped F2/F2 fiber |
| ODMR Dip Frequency (Zero Field) | ~2870 | MHz | Negatively charged NV centers (NVÂŻ) |
| Glass Viscosity (Doping Step) | ~106 | dPa·s | F2 lead-silicate glass (softened, high viscosity) |
| NVÂŻ Zero Phonon Line (ZPL) | ~637 | nm | Confirms presence of magnetically sensitive NVÂŻ centers |
| Refractive Index Contrast (F2 to Silica) | 0.15 | N/A | Low contrast benefits coupling to standard silica fiber |
Key Methodologies
Section titled âKey MethodologiesâThe successful integration of NV-diamond microparticles relied on precise material preparation and a controlled cane-in-tube fiber drawing process:
- Diamond Precursor Preparation:
- Commercially available high-pressure high-temperature (HPHT) diamond microparticles (~1 ”m) were selected.
- Irradiation: Particles were irradiated with 2 MeV electrons (fluence of 1Ă1018 cm-2).
- Annealing: Followed by annealing at 900 °C for 2 h in argon to create NV centers.
- Purification: Oxidized in air (520 °C, 2 h) to remove non-diamond carbon from the surface.
- Preform Fabrication (Cane-in-Tube):
- F2 lead-silicate glass billets were extruded into a rod (drawn into a cane, OD ~0.6 mm) and a tube (ID ~0.9 mm).
- Interface Doping (Dip Coating):
- Processed diamond powder was dispersed in ethanol (~0.4 mg·mL-1 concentration) and sonicated for >30 minutes to reduce agglomeration.
- The F2 glass cane was coated by implementing 25 dips using a dip coater (200 mm/min speed, 30 s dip/wait time) to achieve a uniform microparticle distribution on the surface.
- Fiber Drawing:
- The diamond-coated cane was inserted into the F2 glass tube.
- The assembly was drawn down to fiber (~130 ”m OD) using a drawing tower.
- Reduced pressure was applied during drawing to close the gap, embedding the diamond particles at the ring-shaped inner/outer interface.
- ODMR Characterization:
- Measurements were performed at room temperature using a CW 532 nm laser pump source.
- Microwave (MW) radiation (~1 W) was delivered via an antenna placed close to the fiber to drive the electron-spin transitions.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâAs an expert provider of MPCVD diamond materials, 6CCVD is uniquely positioned to supply the high-purity precursors necessary to replicate and advance this fiber-optic quantum sensing research. The enhanced sensitivity achieved in this study is directly linked to the quality and size of the diamond materialâa core competency of 6CCVD.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research, which relies on maximizing the NV- center yield and coherence time, 6CCVD recommends the following materials:
- Optical Grade Single Crystal Diamond (SCD): Our high-purity SCD plates (low intrinsic nitrogen) allow for precise, controlled nitrogen incorporation (e.g., via N2 gas during growth or ion implantation) to create optimal NV center concentrations.
- High-Purity Polycrystalline Diamond (PCD): For large-volume applications or when cost-efficiency is critical, our high-purity PCD wafers (up to 125 mm diameter) serve as excellent precursors for high-yield microparticle fabrication.
- Custom Nitrogen Doping: We offer precise control over nitrogen concentration during growth, which is crucial for maximizing the density of the magnetically sensitive NV- state, thereby directly improving the shot-noise limited DC magnetic field sensitivity (scaling with 1/âNNV).
Customization Potential
Section titled âCustomization PotentialâThe research highlights the need for specific particle sizes (~1 ”m) and controlled integration geometry. 6CCVDâs in-house engineering capabilities can support the entire material pipeline:
| Research Requirement | 6CCVD Capability | Benefit to Customer |
|---|---|---|
| High-Volume Precursors | SCD/PCD plates up to 125 mm diameter. | Provides large, uniform starting material for high-yield microparticle production. |
| Precise Thickness Control | SCD and PCD thicknesses from 0.1 ”m to 500 ”m. | Allows optimization of precursor volume for subsequent laser cutting or milling into microparticles. |
| Custom Metalization | In-house deposition of Au, Pt, Pd, Ti, W, Cu. | Essential for future integration steps, such such as creating electrical contacts for MW antennae or packaging the fiber end-faces. |
| Surface Finish | Polishing to Ra < 1 nm (SCD) and Ra < 5 nm (PCD). | Ensures optimal surface quality for post-processing steps like irradiation, annealing, and subsequent particle oxidation/cleaning. |
| Global Logistics | Global shipping (DDU default, DDP available). | Ensures rapid and reliable delivery of custom materials worldwide. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in defect engineering and material optimization for quantum applications. We can assist researchers with material selection, nitrogen doping control, and post-growth processing parameters (e.g., advising on optimal irradiation fluence and annealing protocols) necessary for maximizing NV- center yield and coherence time for similar Remote Fiber-Optic Magnetometry projects.
The paper specifically notes that sensitivity can be further enhanced by improving the purity of diamond particles with controlled nitrogen and carbon isotopes [39-41]. 6CCVD is a leading supplier of isotopically enriched diamond materials, providing the foundation for next-generation quantum sensors.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Diamond containing the nitrogen-vacancy (NV) center is emerging as a significant sensing platform. However, most NV sensors require microscopes to collect the fluorescence signals and therefore are limited to laboratory settings. By embedding micron-scale diamond particles at an annular interface within the cross section of a silicate glass fiber, we demonstrate a robust fiber material capable of sensing magnetic fields. Luminescence spectroscopy and electron spin resonance characterization reveal that the optical properties of NV centers in the diamond microcrystals are well preserved throughout the fiber drawing process. The hybrid fiber presents a low propagation loss of âŒ4.0 dB/m in the NV emission spectral window, permitting remote monitoring of the optically detected magnetic resonance signals. We demonstrate NV-spin magnetic resonance readout through 50 cm of fiber. This study paves a way for the scalable fabrication of fiber-based diamond sensors for field-deployable quantum metrology applications.