Analysis of the cavity ring-down signal based on self-consistent equations and the transfer function

In order to better understand the physical nature and measurement process of the cavity ring-down technique and analyze the signal,the self-consistent equations and the Q concept of a passive optical cavity were used to deduce the basic principle.The transfer function was introduced to analyze the essential features of different signals under different conditions.Results show that this analytical method is reliable and can provide theoretical guide for cavity ring-down measurements in different areas such as the calibration of ultra-low loss films and the measurement of the intra-cavity absorption spectrum.