和频与差频振动光谱实验构型的分析模拟

Analysis and Simulation of Experimental Configurations for Sum Frequency Generation and Difference Frequency Generation Vibrational Spectroscopy

实验构型分析是定量分析和频振动光谱的基础.变换实验构型,不仅要考虑某一振动模式信号强度的大小,还要考虑不同构型下的信号检测效率.现有的和频振动光谱实验构型分析主要考虑前者.本文探讨实验构型分析中所涉及的信号检测效率问题,模拟在共向式和频(差频)及对射式和频(差频)振动光谱实验中选取何种实验构型对采集信号光更加合理有效.利用相干光学过程能量守恒和动量守恒原理,分析了入射角及入射光频率等因素对信号出射角的影响,并模拟了信号出射角与入射角及入射光频率的关系,得到了可选的入射角组合最多、出射角随入射光频率变化最小的实验构型.结果表明,和频振动光谱采取共向式实验构型,差频振动光谱采取对射式实验构型,有利于信号采集,进而有利于用实验构型分析方法对和频(差频)振动光谱进行定量研究.

The analysis of experimental configurations is the foundation for quantitative analysis in sum frequency generation vibrational spectroscopy （SFG-VS）. The incident angles affect the signal intensity of some modes of vibration and the detection efficiency of the SFG signal. However, the issue of detection efficiency has not been included in previous experimental configuration analysis studies. According to the principle of the conservation of energy and momentum in coherent optics we simulated and analyzed the effect of incident angles, frequency of the incident light, and other factors on the output signal angle of difference frequency generation vibrational spectroscopy （DFG-VS） and SFG-VS. We intended to determine the reasonable and effective experimental configurations with more combinations of incident angles and less dispersion of the signal output angle. We found that SFG-VS with the co-propagation experimental configuration and DFG-VS with the counter-propagation experimental configuration favour the collection of the signal and quantitave analysis of the SFG-VS and DFG-VS.