Mid‐infrared (MIR) spectroscopy, which has important applications in medicine, environmental monitoring, materials, and food science, is widely performed using Fourier transform infrared (FTIR) spectrometers as gold standard. Despite decades of development, FTIR systems are vulnerable to vibration and have limited temporal resolution due to reliance on mechanically scanned mirrors and MIR direct detectors that have a slower response than their near‐infrared counterparts. Using cryogenically cooled detectors, state‐of‐the‐art FTIR systems have reached a signal‐to‐noise ratio (SNR) of ≈6000 at 1 s integration time (at 4 cm⁻¹ spectral resolution). Here, a novel MIR upconversion spectrometer (MIRUS) is presented with a record‐high SNR > 10 000 at 1 s (6 cm⁻¹ resolution), outperforming FTIR systems by circumventing the need for sophisticated cooling and any moving part, thus enabling operation in harsh environments. It has a spectral coverage of 6–12 µm—the broadest for an upconversion spectrometer to date. The MIRUS uses broadband intracavity upconversion to convert the signal spanning the MIR fingerprint region to the near‐infrared where sensitive Si‐detector based spectrometers operate with rates easily reaching kilo spectra per second. Applications of MIRUS for gas sensing, plastic identification, and rapid photopolymerization monitoring are demonstrated.

中文翻译：

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6–12 µm区域内的室温，高SNR上转换光谱仪

中红外（MIR）光谱在医学，环境监测，材料和食品科学中具有重要应用，广泛使用傅立叶变换红外（FTIR）光谱仪作为金标准进行。尽管已有数十年的发展，但由于依赖机械扫描镜和MIR直接探测器的原因，FTIR系统易受振动影响，并且时间分辨率有限，因为它们的响应速度比近红外系统慢。使用低温冷却的探测器，最先进的FTIR系统在1 s积分时间（4 cm ^-1光谱分辨率）下达到了约6000的信噪比（SNR ）。在这里，提出了一种新型的MIR上转换光谱仪（MIRUS），其在1 s（6 cm ^-1分辨率），从而避免了对复杂冷却和任何运动部件的需求，从而胜过FTIR系统，从而能够在恶劣的环境下运行。它的光谱覆盖范围为6–12 µm，是迄今为止上转换光谱仪的最宽光谱范围。MIRUS使用宽带腔内上变频将跨越MIR指纹区域的信号转换为近红外信号，其中基于Si探测器的灵敏光谱仪的工作速率很容易达到每秒千光谱。展示了MIRUS在气体传感，塑料识别和快速光聚合监测中的应用。