Generating Coherent Raman Scattering Using a Molecular Optomechanical Cavity

Coherent Raman scattering, e.g., coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS), has emerged as a powerful tool for label-free molecular imaging in biological and biomedical systems. Here we develop an optomechanical approach for coherent Raman spectroscopy with a focus on the CARS and SRS. The results show that the Raman cross section can be significantly enhanced by increasing the pump strength. It turns out that the CARS signal is robust to the external temperature, yielding an order of magnitude amplification due to √N collectivity. We further find that the power spectrum of the emission is dominated by the SRS process. The SRS signal presents an anti-Stokes component appreciably stronger than the Stokes one. Our work suggests a new scheme for generating coherent Raman signals with enhanced stability and signal-to-noise ratio, which would be beneficial for molecular spectroscopy.相干拉曼散射（coherent Raman scattering），例如相干反斯托克斯拉曼散射（coherent anti-Stokes Raman scattering, CARS）与受激拉曼散射（stimulated Raman scattering, SRS），已成为生物及生物医学系统中实现无标记分子成像的有力工具。本文开发了一种面向相干拉曼光谱的光力学方案，重点聚焦CARS与SRS技术。研究结果显示，提升泵浦强度可显著增强拉曼散射截面。进一步分析表明，CARS信号对外界温度具备优异鲁棒性，且因√N集体效应实现了一个数量级的信号放大。我们还发现，发射信号的功率谱主要由SRS过程主导；SRS信号的反斯托克斯分量显著强于斯托克斯分量。本工作提出了一种可提升相干拉曼信号稳定性与信噪比的全新方案，有望为分子光谱学研究带来助益。