Ultra-broadband quantum infrared spectroscopy extending to 20 {\textmu}m
Abstract
Quantum infrared spectroscopy (QIRS), which exploits quantum interference between photon-pair generation processes, enables infrared spectroscopy using only visible and near-infrared (VNIR) light sources and detectors. Extending the spectral coverage of QIRS into the long-wavelength infrared region up to 20 {\textmu}m is crucial for the identification and characterization of a broad range of materials. However, implementing QIRS beyond 10 {\textmu}m has been challenging because the nonlinear materials used to date do not provide suitable photon-pair sources in this spectral region. Here, we design a wavelength-tunable photon-pair source based on a gallium selenide crystal and develop a QIRS system covering a broad spectral range from 8.6 to 20 {\textmu}m. Using this system, we measure the transmittance spectrum of a polystyrene film and observe characteristic absorption bands beyond 10 {\textmu}m relevant to identifying polystyrene and to probing local chain conformation. These results demonstrate that QIRS is capable of covering the entire molecular fingerprint region.
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BibTeX
@misc{mukai2026ultrabroadband,
title = {{Ultra-broadband quantum infrared spectroscopy extending to 20 \textmum}},
author = {Yu Mukai and Ryo Okamoto and Shigeki Takeuchi},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.00561},
eprint = {2611.00561},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.00561},
}
RIS
TY - UNPB
TI - Ultra-broadband quantum infrared spectroscopy extending to 20 {\textmu}m
AU - Yu Mukai
AU - Ryo Okamoto
AU - Shigeki Takeuchi
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.00561
UR - https://arxiv.org/abs/2611.00561
AB - Quantum infrared spectroscopy (QIRS), which exploits quantum interference between photon-pair generation processes, enables infrared spectroscopy using only visible and near-infrared (VNIR) light sources and detectors. Extending the spectral coverage of QIRS into the long-wavelength infrared region up to 20 {\textmu}m is crucial for the identification and characterization of a broad range of materials. However, implementing QIRS beyond 10 {\textmu}m has been challenging because the nonlinear materials used to date do not provide suitable photon-pair sources in this spectral region. Here, we design a wavelength-tunable photon-pair source based on a gallium selenide crystal and develop a QIRS system covering a broad spectral range from 8.6 to 20 {\textmu}m. Using this system, we measure the transmittance spectrum of a polystyrene film and observe characteristic absorption bands beyond 10 {\textmu}m relevant to identifying polystyrene and to probing local chain conformation. These results demonstrate that QIRS is capable of covering the entire molecular fingerprint region.
ER -