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Robust 1-μm-Resolution Magnetic Probe Enabled by Optical Trapping of Nanodiamonds on a Tapered Fiber

MetadataDetails
Publication Date2025-06-17
JournalNano Letters
AuthorsDie Fang, Yibo Wang, Xin Wang, Yachen Gao, Zhengfei Zhang
InstitutionsHefei University of Technology, Zhejiang University

High-resolution magnetic field scanning is critical for investigating nanoscale spin systems and characterizing defects in microelectronic devices. We present a fabrication-free approach to create robust magnetic probes with 1-μm spatial resolution by synergizing the quantum magnetic sensitivity of nitrogen-vacancy (NV) centers in nanodiamonds with the enhanced photon efficiency of tapered fibers. Through gradient-force optical trapping, nanodiamonds are precisely positioned at the fiber tip, where van der Waals forces immobilize them without requiring micro-nanoprocessing. In addition to possessing high spatial resolution, the probe exhibits a magnetic sensitivity reaching <mml:math xmlns:mml=“http://www.w3.org/1998/Math/MathML”&gt;&lt;mml:mn&gt;80&lt;/mml:mn&gt;&lt;mml:mo&gt;⁡&lt;/mml:mo&gt;&lt;mml:mi&gt;μ&lt;/mml:mi&gt;&lt;mml:mi&gt;T&lt;/mml:mi&gt;&lt;mml:mo&gt;/&lt;/mml:mo&gt;&lt;mml:msqrt&gt;&lt;mml:mrow&gt;&lt;mml:mi&gt;Hz&lt;/mml:mi&gt;&lt;/mml:mrow&gt;&lt;/mml:msqrt&gt;&lt;/mml:math>. By demonstrating a magnetic field scan of crossed microwires, this method can be extended to measure tiny magnetic structures or microcircuits, leveraging the integrated photonic enhancement of tapered fibers for robust high signal-to-noise sensing.

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