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 Adelaide, University of Melbourne |
| Citations | 37 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study demonstrates a novel, robust, fiber-based platform for remote magnetic field sensing utilizing Nitrogen-Vacancy (NV) centers in diamond microparticles.
- Core Innovation: Integration of micron-sized NV-containing diamond particles into an F2 lead-silicate glass fiber using a new interface doping technique (cane-in-tube approach), confining particles to an annular interface.
- Performance Enhancement: The use of 1 ”m microdiamonds (vs. nanodiamonds) and the interface geometry resulted in a sensitivity improvement of over one order of magnitude compared to previous volume-doped fibers.
- Key Sensitivity Achievements (Room Temperature DC Magnetic Field): Achieved 350 nT/âHz for localized characterization (side/side scheme) and 650 nT/âHz for fiber-transmitted sensing over 20 cm (side/end scheme).
- Remote Sensing Capability: Demonstrated optically detected magnetic resonance (ODMR) readout via longitudinal end/end scheme over a 50 cm fiber length, achieving a sensitivity of ~3 ”T/âHz.
- Material Preservation: The high viscosity (~106 dPa·s) of the F2 glass during the drawing process preserved the fluorescence and spin properties of the NV centers by hindering chemical dissolution.
- Optical Benefits: Interface doping reduced fiber propagation loss (~4 dB/m) compared to volume doping (~10 dB/m), facilitating efficient guidance and collection of NV-fluorescence in the central fiber region.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Fiber Material | F2 Lead-Silicate Glass | N/A | Schott Glass Co. |
| Diamond Particle Size | ~1 | ”m | Used for doping (MSY 0.75-1.25). |
| NV Center Concentration | ~1 | ppm | Estimated in processed diamond particles. |
| Fiber Outer Diameter (OD) | ~130 | ”m | Drawn F2/F2 fiber. |
| Interface Diameter | ~9 | ”m | Inner/outer fiber interface location. |
| Excitation Wavelength | 532 | nm | Continuous-Wave (CW) laser pump source. |
| Propagation Loss (532 nm) | ~4.6 | dB/m | Diamond-doped F2/F2 fiber. |
| Propagation Loss (600-800 nm) | ~4.0 | dB/m | NV-fluorescence emission range. |
| DC Magnetic Sensitivity (Side/Side) | 350 | nT/âHz | Localized characterization. |
| DC Magnetic Sensitivity (Side/End) | 650 | nT/âHz | 20 cm fiber transmission length. |
| DC Magnetic Sensitivity (End/End) | ~3 | ”T/âHz | 50 cm fiber transmission length. |
| ODMR Readout Contrast (End/End) | ~2.5 | % | Measured over 50 cm fiber. |
| Glass Viscosity (Doping Step) | ~106 | dPa·s | F2 glass drawing temperature (softened). |
| NV Fluorescence Intensity Ratio | ~17 | N/A | Inner region intensity compared to outermost region. |
| Refractive Index (F2 Glass) | 1.6 | N/A | Leads to better index-matching with silica (1.45). |
Key Methodologies
Section titled âKey MethodologiesâThe intrinsic magnetically sensitive fiber was fabricated using a cane-in-tube approach combined with interface doping.
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Diamond Material Processing:
- Commercially available high-pressure high-temperature (HPHT) diamond microparticles were used.
- Irradiation: 2 MeV electrons to a fluence of 1Ă1018 cm-2.
- Annealing: 900 °C for 2 hours in argon to create NV centers.
- Oxidation: 520 °C for 2 hours in air to remove non-diamond carbon.
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Preform Preparation (Cane and Tube):
- F2 glass billets were extruded into a rod (~11 mm OD) and a tube (~9 mm OD, ~0.9 mm ID).
- The rod was drawn down to a cane (~0.6 mm OD).
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Interface Doping (Cane Coating):
- A diamond solution was prepared by dispersing processed diamond powder into ethanol (~0.4 mg·mL-1).
- The F2 glass cane was coated by implementing 25 dips using a dip coater (200 mm/min speed; 30 s dip/withdrawal time).
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Fiber Drawing:
- The diamond-coated cane was inserted into the F2 glass tube.
- The cane-in-tube assembly was drawn down to fiber (~130 ”m OD) using a drawing tower.
- Reduced pressure was applied during drawing to close the gap between the cane and tube, embedding the diamond particles at the resulting inner/outer interface.
- The drawing process occurred at a high glass viscosity (~106 dPa·s), which was critical for preserving the NV centers.
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Sensing Characterization:
- Three excitation/collection schemes were used for fluorescence and ODMR measurements:
- Side/Side: Confocal collection at the excitation site (localized sensing).
- Side/End: Side excitation (Port A), longitudinal collection at the distal end (Port B, 20 cm length).
- End/End: Longitudinal excitation (Port C), longitudinal collection at the distal end (Port B, 50 cm length).
- ODMR was driven by a scanning microwave (MW) frequency applied via an antenna near the excitation region.
- Three excitation/collection schemes were used for fluorescence and ODMR measurements:
Commercial Applications
Section titled âCommercial ApplicationsâThis technology provides a robust, fiber-integrated platform for quantum sensing, moving high-sensitivity magnetometry out of laboratory settings into field-deployable systems.
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Quantum Metrology and Sensing:
- Field-Deployable Magnetometers: Creating robust, portable sensors for measuring DC magnetic fields in remote or harsh environments.
- Persistent Magnetic Field Monitoring: Long-term, continuous monitoring applications where fiber integration is essential.
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Defense and Security:
- Remote Detection: Utilizing the fiberâs length (50 cm demonstrated) for sensing magnetic anomalies or signatures at a distance.
- Secure Communications: Potential integration into quantum information technology systems leveraging NV spin properties.
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Biomedical and Industrial Imaging:
- Bio-Medical Thermometry and Imaging: While the focus here is magnetometry, NV centers are widely used for nanoscale temperature sensing and imaging, suggesting potential for fiber-optic thermal probes.
- Industrial Monitoring: Sensing magnetic fields in complex machinery or infrastructure where traditional sensors are impractical due to size or electromagnetic interference.
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Fiber Optic Components:
- Novel Photonic Emitters: The interface embedding technique is an effective approach for incorporating other photonic emitters into fiber channels for various sensing or light generation applications.
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.