We proposed a coherent radiation scheme based on double-stimulated Raman scattering (SRS) induced cascaded four-wave mixing (FWM) in a mixed methanol–ethanol solution. The SRS of methanol has two characteristic vibrational peaks, which are attributed to the symmetric stretching vibration of –CH3 and the antisymmetric stretching vibration of –CH3. The addition of ethanol enhances the antisymmetric stretching vibration mode, and intensities of two peaks were similar when the volume ratio of methanol to ethanol was 7.5:2.5. Resonant amplification of the two SRS signals is achieved by refocusing the scattered light, and the stronger self-focusing effect not only converges the two beams but also generates a plasma-enhanced SRS process, realizing cascaded FWM. The frequency difference Δω between two FWM beams matches the frequency difference ΔΩ between the vibrational energy levels of the symmetric and antisymmetric stretching vibrations, and the stimulated excitation enhances FWM signals. The output coherent radiation light is a large broadband ranging from 592 to 668 nm and 721 to 797 nm, with a wavelength interval of about 3 nm. The intensity of light radiated at different wavelengths is not the same, with the strongest light at the center of the wavelength (630 and 759 nm). This technique has the potential to contribute to the development of a multi-wavelength cascaded Raman laser.

中文翻译：

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级联四波混合工艺：在混合溶液中实现双受激拉曼散射的超连续相干辐射的关键


我们提出了一种基于混合甲醇-乙醇溶液中双刺激拉曼散射 （SRS） 诱导级联四波混合 （FWM） 的相干辐射方案。甲醇的 SRS 具有两个特征振动峰，分别归因于 –CH3 的对称拉伸振动和 –CH3 的反对称拉伸振动。乙醇的加入增强了反对称拉伸振动模式，当甲醇与乙醇的体积比为 7.5：2.5 时，两个峰的强度相似。通过对散射光进行重新聚焦来实现两个 SRS 信号的谐振放大，更强的自聚焦效应不仅会聚了两束光束，还产生了等离子体增强的 SRS 过程，实现了级联 FWM。两个 FWM 光束之间的频率差 Δω 与对称和反对称拉伸振动的振动能级之间的频率差 ΔΩ 相匹配，受激激励增强了 FWM 信号。输出相干辐射光是 592 至 668 nm 和 721 至 797 nm 的大宽带，波长间隔约为 3 nm。不同波长辐射的光强度不同，最强的光位于波长中心（630 和 759 nm）。这项技术有可能为多波长级联拉曼激光器的发展做出贡献。