基于改进时频特性的高精度太赫兹光谱测量系统定量分析研究

QUANTITATIVE ANALYSIS OF HIGH PRECISION TERAHERTZ SPECTROMETRY SYSTEM BASED ON IMPROVED TIME-FREQUENCY FEATURE

太赫兹时域光谱测量过程中的许多系统误差,如噪声误差、幅值误差、位置误差以及样品倾斜误差等,直接影响光学常数的测量精度。针对正入射反射式太赫兹光谱测量的误差源进行系统性研究,提出一种基于时频分析的不确定误差函数,为系统性误差校正提供理论基础。通过对每个单误差源进行仿真分析,结果表明消光系数比折射率更受误差的影响,光学常数的偏差随着位置误差增加而变大,且较高频率下太赫兹时域光谱测量中位置和样本倾斜误差也影响测量精度。因此可以通过系统误差公式的校正增强测量的精度。

Many systematic errors in terahertz time domain spectroscopy (THz-TDS),such as noise error,amplitude error,position error and sample skew error,directly affect the measurement accuracy of optical constants.In this paper,we systematically studied the error sources of terahertz spectroscopy with normal incidence and reflection modes.We proposed an uncertain error function based on time-frequency analysis to provide the theoretical basis for systematic error correction.The simulation results of each single error source show that the extinction coefficient is more affected by the error than the refractive index.The deviation of optical constants increases with the increase of position errors,and the position and sample skew errors in terahertz time domain spectroscopy at higher frequencies also affect the measurement accuracy.Therefore,the accuracy of measurement can be enhanced by the correction of the system error formula.