Theoretical analysis of cavity saturation spectroscopy of weak molecular absorbance

A theoretical analysis of sub-Doppler molecular saturation spectroscopy by use of a confocal Fabry--Perot (CFP) cavity is presented. The effects of gas pressure, cavity length and mirror reflectivity on the saturation dip amplitude are analysed. Such a treatment can provide the optimum conditions and a guidance for the experiment of saturating the weak molecular absorption lines.