Kröll S, Aldén M, Berglind T, Hall R J
Appl Opt. 1987 Mar 15;26(6):1068-73. doi: 10.1364/AO.26.001068.
A simple model is presented as an aid in understanding, first, the relative noise performance and, second, the noise reduction achievable by referencing, in different experimental approaches to single shot broadband coherent anti-Stokes Raman scattering (CARS). Qualitative agreement is obtained with previous experimental investigations of CARS noise. The broadband dye laser radiation is described as the sum of independent modes with random phases. The dye laser contribution to the CARS noise is then approximately inversely proportional to the square root of the number of dye laser modes generating the detected signal. A fundamental idea is that in Raman resonant spectra only the number of Stokes modes actually participating in driving the Raman resonance should be counted. This means, e.g., that for narrow Raman resonances, as in an atmospheric flame, the noise generated by the dye laser will be higher for a single-mode pump laser than for a multimode pump laser with the experimental CARS configuration normally employed. The implications of the model for the dual broadband type CARS techniques are also discussed.
提出了一个简单模型，以帮助理解，其一，在单次宽带相干反斯托克斯拉曼散射（CARS）的不同实验方法中，相对噪声性能；其二，通过参考可实现的降噪效果。该模型与之前关于CARS噪声的实验研究获得了定性一致。宽带染料激光辐射被描述为具有随机相位的独立模式之和。然后，染料激光对CARS噪声的贡献大致与产生检测信号的染料激光模式数量的平方根成反比。一个基本观点是，在拉曼共振光谱中，只应计算实际参与驱动拉曼共振的斯托克斯模式数量。这意味着，例如，对于窄拉曼共振，如在大气火焰中，在通常采用的实验CARS配置下，单模泵浦激光产生的染料激光噪声将高于多模泵浦激光产生的噪声。还讨论了该模型对双宽带型CARS技术的影响。
