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20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier
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Mid-infrared to ultraviolet efficient multiphoton frequency upconversion in NbOI2 crystals
Song Zhu1, Xuan Mao2, Congliao Yan3
1National Key Laboratory of Microwave Photonics, Nanjing University of Aeronautics and Astronautics, Nanjing, China.
Nature Communications
|March 14, 2026
Summary
Researchers achieved efficient, broadband mid-infrared (MIR) upconversion using NbOI₂. This phase-matching-free method enables advanced MIR nanophotonics for imaging and sensing applications.
Area of Science:
- Photonics and Nanomaterials
- Nonlinear Optics
Background:
- Efficient mid-infrared (MIR) frequency upconversion is crucial for advanced optical applications.
- Existing methods face limitations due to phase-matching and low nonlinear coefficients in optical materials.
Purpose of the Study:
- To demonstrate phase-matching-free, broadband, and efficient multiphoton frequency upconversion.
- To explore the potential of NbOI₂ as a material for MIR nanophotonics.
Main Methods:
- Utilized niobium oxyiodide (NbOI₂) for nonlinear frequency upconversion.
- Investigated nonlinear frequency mixing across a broad spectral window (1500-5000 nm).
- Demonstrated broadband MIR upconversion imaging using a silicon camera.
Main Results:
- Observed harmonic generation from 2nd to 11th order, spanning MIR to ultraviolet.
- Achieved nonlinear frequency mixing efficiencies up to 6×10⁻⁴ W⁻¹, outperforming metasurfaces.
- Successfully demonstrated direct MIR upconversion imaging.
Conclusions:
- NbOI₂ enables efficient, phase-matching-free, broadband MIR upconversion.
- Established NbOI₂ as a promising platform for MIR nanophotonics.
- Highlights potential for advanced ultrabroadband imaging, sensing, and spectral conversion.
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