Ultrafast coherent Raman spectroscopy is a powerful tool for label-free vibrational imaging of living cells, tracking of transient chemical kinetics, and flow cytometry and cell sorting. Unfortunately, virtually all methods of ultrafast coherent Raman spectroscopy can only acquire Raman spectra in the fingerprint (FP) region (200–1800 cm^–1) or the high-frequency (HF) region (2800–3200 cm^–1). While ultrafast coherent Raman spectroscopy covering both regions is achievable with ultrashort (<10 fs) pulses as an excitation light source, such a scheme lacks general applicability due to the difficulty of generating and handling ultrashort pulses, phototoxicity originating from their high peak power, and compromised sensitivity in both the FP and HF regions. Here, we demonstrate ultrafast (24,000 spectra/s), dual-band (200–1600 and 2800–3200 cm^–1), highly sensitive coherent Raman spectroscopy without the need for ultrashort pulses. This is made possible by employing rapid-scan Fourier-transform coherent anti-Stokes Raman scattering based on two passively synchronized mode-locked lasers. As different types of molecular structural information can be obtained in these two regions, the ability of our method to rapidly and sensitively acquire dual-band Raman spectra is expected to open a plethora of opportunities in industrial, biomedical, and pharmaceutical applications.

中文翻译：

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无超短脉冲的超快双波段相干拉曼光谱

超快相干拉曼光谱是一种强大的工具，可用于活细胞的无标记振动成像、瞬态化学动力学跟踪以及流式细胞术和细胞分选。不幸的是，几乎所有超快相干拉曼光谱方法都只能获取指纹 (FP) 区域 (200–1800 cm ^–1 ) 或高频 (HF) 区域 (2800–3200 cm ^{–1 ) 中的拉曼光谱}). 虽然用超短 (<10 fs) 脉冲作为激发光源可以实现覆盖两个区域的超快相干拉曼光谱，但由于难以生成和处理超短脉冲、源自其高峰值功率的光毒性以及FP 和 HF 区域的灵敏度都受到影响。在这里，我们展示了超快（24,000 个光谱/秒）、双波段（200–1600 和 2800–3200 cm ^–1), 不需要超短脉冲的高灵敏度相干拉曼光谱。这是通过采用基于两个被动同步锁模激光器的快速扫描傅里叶变换相干反斯托克斯拉曼散射实现的。由于可以在这两个区域获得不同类型的分子结构信息，我们的方法能够快速、灵敏地获取双波段拉曼光谱，有望在工业、生物医学和制药应用中开辟大量机会。