发表机构
University of Bristol（布里斯托大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究将未探测光子光谱学拓展至20微米波长，采用BGGSe非线性干涉仪结合硅探测器，成功实现7.8-20微米宽带吸收光谱测量及SF₆气体探测，大幅拓展了该技术的可及光谱范围。
AI 中文摘要
采用未探测光子的光谱学技术，可通过较短波长信号场的干涉来测量样品在长波长下的光谱响应，无需直接探测探测样品的光。此前在分子指纹区开展的未探测光子光谱学演示已达到约10.5微米，而更长波长的探索仍十分有限。本研究将该方法拓展至20微米波长，展示了基于BaGa₂GeSe₆（BGGSe）非线性干涉仪的红外未探测光子光谱学，仅采用硅探测器探测近红外（NIR）信号。BGGSe晶体的旋转可实现宽波长调谐，对信号干涉图进行傅里叶变换分析可得到对应的闲频光谱与样品透射率。采用Kapton在7.8-20微米波长范围内开展宽带吸收光谱学演示，测得的吸收结果与独立红外测量结果一致。该系统还被用于在10.55微米附近通过光谱学探测六氟化硫（SF₆）气体。这些结果在保留基于硅的近红外探测的同时，大幅拓展了未探测光子光谱学的可及光谱范围。
英文摘要
Spectroscopy with undetected photons allows the spectral response of a sample at long wavelengths to be measured through interference of a shorter-wavelength signal field, without directly detecting the light that probes the sample. Previous demonstrations of undetected-photon spectroscopy in the molecular fingerprint region have reached approximately 10.5 microns, leaving longer wavelengths largely unexplored. Here, we extend this approach to 20 microns wavelength, demonstrating infrared undetected-photon spectroscopy using a BaGa2GeSe6 (BGGSe)-based nonlinear interferometer while only the near-infrared (NIR) signal is detected using a silicon detector. Rotation of the BGGSe crystal provides broad wavelength tuning, and Fourier-transform analysis of the signal interferograms yields the corresponding idler spectra and sample transmittance. Broadband absorption spectroscopy is demonstrated using Kapton across a 7.8-20 microns wavelength range, with the measured absorption agreeing with independent infrared measurements. The same system is further employed to detect sulfur hexafluoride (SF6) gas via spectroscopy near 10.55 microns. These results substantially extend the accessible spectral range of spectroscopy with undetected photons while retaining silicon-based NIR detection.
