Ultrabroadband and Reversible Tuning of Infrared Plasmons in van der Waals Metal Films.

Bi, Wenqi; Zheng, Yuqing; Meng, Xiangkai; Ma, Junwei; Li, Yangyang; Zhang, Haochen; Sun, Xinying; Wang, Zhiyu et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Reconfigurable infrared plasmons are central to emerging nanophotonic technologies, yet their practical impact remains constrained by limited tuning bandwidth, poor reversibility, and material-specific spectral windows. Here we demonstrate ultrabroadband and fully reversible tuning of infrared plasmons in metallic van der Waals NbSe2 films enabled by gate-controlled lithium-ion intercalation. Ion intercalation provides a unique pathway to simultaneously modulate free-carrier density and screening from high-energy interband transitions, jointly reshaping both plasmon frequency and oscillator strength. As a result, plasmon resonances can be continuously swept over an unprecedented spectral span exceeding 5500 cm-1 within a single material platform, covering the telecom, mid-infrared and thermal far-infrared region. Leveraging this broad and reversible tunability, we realize electrically tunable wavelength-selective thermal emitters and thermal display patterns through plasmon-mediated emissivity modulation. Our results establish ion-intercalated van der Waals metals as a versatile and programmable platform for ultrabroadband tunable infrared nanophotonics and reversible thermal-radiation control.