光外差腔衰荡光谱理论研究

提出了简化的光外差腔衰荡光谱技术，避免了通常腔衰荡光谱对衰荡时间的直接测量，同时消除了腔镜损耗的共模直流信号的测量.理论上其测量灵敏度可以达到量子噪声极限，而且技术实现相对简单，更适合于分子振转光谱研究.此外，还在理论上分析了该光谱技术具有的Gauss线型的一次微分光谱线型的特点，并讨论了一些实验参量对谱线强度和线型的影响，进而给出了最佳实验参量. 关键词： 光外差 腔衰荡光谱

Theoretical investigation of optical heterodyne cavity ring down spectroscopy

A simplified optical heterodyne cavity ring down spectroscopy, which is relatively easy to implement and more suitable for molecular ro-vibrational spectrum study, is suggested in the present paper. It avoids measuring the ring down time directly, and in addition cancels the DC common mode signal resulting from the loss of the cavity mirrors. Theoretically, it could reach the quantum noise detection limit. Furthermore, its lineshape of the first derivative of Gaussian profile is theoretically analyzed, and the dependence of the spectral intensity and lineshape on some experimental parameters are also discussed, and thus the optimal parameters are obtained.