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arXiv · 2601.18031

Video-rate mid-infrared imaging in the molecular fingerprint region via nanosecond non-degenerate two-photon absorption

Evan P. Garcia·Yryx Y. L. Palacios·Ryan Nguyen·Adam Hanninen·Aleksei I. Noskov·Eric O. Potma·Dmitry A. Fishman
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Abstract

Non-degenerate two-photon absorption (NTA) offers an attractive route for wide-field mid-infrared (MIR) imaging by mapping long wavelength information into the spectral detection windows of mature near-infrared detector technologies. However, existing NTA implementations rely almost exclusively on complex, large-footprint femtosecond laser systems, severely limiting practicality and scalability. Here, we demonstrate an NTA imaging platform that replaces the ultrafast laser with a compact nanosecond mid-IR source coupled to a high-definition indium gallium arsenide (InGaAs) camera. Operating in the nanosecond regime removes stringent temporal-overlap requirements, dramatically simplifying system architecture while preserving high nonlinear sensitivity. Using this approach, we achieve chemically selective, wide-field imaging deep into the mid-IR molecular fingerprint region and demonstrate, for the first time, video-rate NTA imaging in this spectrally rich regime. By combining relaxed alignment constraints, compact excitation, and high-speed fingerprint-region imaging, this work establishes nanosecond NTA as a practical and scalable foundation for next-generation mid-IR chemical imaging.

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Evan P. Garcia, Yryx Y. L. Palacios, Ryan Nguyen, Adam Hanninen, Aleksei I. Noskov, Eric O. Potma, Dmitry A. Fishman. 2026-01-25. Video-rate mid-infrared imaging in the molecular fingerprint region via nanosecond non-degenerate two-photon absorption. https://arxiv.org/abs/2601.18031

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