Researchers at University of Tsukuba have successfully measured electric fields near the surfaces of two-dimensional layered materials with femtosecond (10⁻¹⁵ s) temporal and nanometer (10⁻⁹ m) spatial resolution. They employed a diamond containing a nitrogen-vacancy center—a lattice defect—as a probe within an atomic force microscope, enabling atomic-scale spatial precision.

Tsukuba, Japan—When nitrogen is incorporated as an impurity in a diamond crystal, the absence of a neighboring carbon atom forms a nitrogen-vacancy (NV) center. Applying an electric field to diamond containing NV centers modifies its refractive index, a phenomenon known as the electro-optic (EO) effect. Notably, this effect has not been observed in pure diamond alone.

In previous work, the research team used a femtosecond laser to detect lattice vibrations in diamond with high sensitivity by measuring the EO effect in high-purity diamond containing NV centers. These results demonstrated that diamond can act as an ultrafast EO crystal and serve as a probe—termed a diamond NV probe—for measuring electric fields.

In the present study, the researchers combined the ultrafast EO effect of diamond NV centers with atomic force microscopy to develop a spatiotemporal microscope capable of measuring local electric field dynamics with femtosecond temporal and nanometer spatial resolution. Using this approach, they successfully detected electric fields near the surface of a tungsten diselenide (WSe₂) sample—a two-dimensional layered material—with temporal and spatial resolutions better than 100 fs and 500 nm.

Owing to the NV center's sensitivity to spin states and thermal fluctuations, this diamond-based probe holds potential not only for electric field detection but also for nanoscale magnetic and thermal sensing.

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This research was supported by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS) (Grant Nos. 25H00849 (M.H.), 22J11423 (T.I.), 22KJ0409 (T.I.), 23K22422 (M.H.), 24K01286 (T.A.), 24H00416 (S.Y.), and 23H00264 (H.S.)), and by CREST, Japan Science and Technology Agency (Grant No. JPMJCR1875) (M.H.).

Original Paper

Title of original paper:

An ultrafast diamond nonlinear photonic sensor

Journal:

Nature Communications

DOI:

10.1038/s41467-025-63936-8

Correspondence

Professor HASE Muneaki
Institute of Pure and Applied Sciences, University of Tsukuba

Associate Professor AN Toshu
School of Materials Science, Japan Advanced Institute of Science and Technology

Professor Paul Fons
Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University

Related Link

Institute of Pure and Applied Sciences