Improving the spectral acquisition rate of broadband mid-infrared spectroscopy promises further advancements of molecular science and technology. Unlike pump-probe spectroscopy, which requires repeated measurements with different pump-probe delays, continuous spectroscopy running at a high spectral acquisition rate enables transient measurements of fast non-repeating phenomena or statistical analysis of a large amount of spectral data. Recently, Fourier-transform infrared spectrometers with rapid delay scan mechanisms including dual-comb spectrometers have significantly improved the measurement rate up to ~1 MSpectra s⁻¹ that is fundamentally limited by the signal-to-noise ratio. Here, we overcome the limit and demonstrate the fastest continuous broadband mid-infrared spectrometer running at 80 MSpectra s⁻¹ by implementing a wavelength-swept time-stretch spectroscopy technique. Our proof-of-concept experiment demonstrates broadband absorption spectroscopy of phenylacetylene from 4.4 to 4.9 μm (2040–2270 cm⁻¹) at a resolution of 15 nm (7.7 cm⁻¹) with a signal-to-noise ratio of 85 without averaging and a shot-to-shot fluctuation of 1.3%.

提高宽带中红外光谱仪的光谱采集速率有望进一步推动分子科学和技术的发展。与需要以不同的泵探针延迟进行重复测量的泵探针光谱法不同，以高光谱采集速率运行的连续光谱法可以对快速的非重复现象进行瞬态测量或对大量光谱数据进行统计分析。近来，具有快速延迟扫描机制的傅立叶变换红外光谱仪（包括双梳状光谱仪）显着提高了测量速率，最高达到〜1 MSpectra s ^-1，而该速率基本上受信噪比限制。在这里，我们克服了这一限制，并展示了运行速度为80 MSpectra s的最快的连续宽带中红外光谱仪^-1通过实施波长扫描时间拉伸光谱技术。我们的概念验证实验表明，苯乙炔的宽带吸收光谱为4.4至4.9μm（2040-2270 cm ^-1），分辨率为15 nm（7.7 cm ^-1），信噪比为85，而没有平均镜头之间的波动幅度为1.3％。