时间-频率联合分析消除太赫兹光谱干涉

Joint Time-Frequency Analysis for Removing the Spectral Interference of Terahertz

基于Fourier变换的传统太赫兹时域光谱分析技术从不同长度的太赫兹信号中产生了不一致的光谱结果,增加太赫兹时域采样长度又会造成光谱的干涉,不利于太赫兹光谱测量的研究和应用。应用小波变换方法对太赫兹波谱作时间—频率联合分析,将不同时刻的太赫兹波谱展开到二维的时间-频率平面,消除了光谱分析的不一致性和光谱干涉的影响。

Conventional Fourier-transform mixes the frequency components of the entire temporal terahertz waveform in one frequency domain;therefore,it cannot distinguish the terahertz frequency in the main pulse from the noise frequency in the pulse tail.Thus traditional Fourier-transform produces inconsistent spectra from different scanning lengths of terahertz pulse.And the interference spectrum appears when the THz echo pulse is recorded.The authors applied wavelet-transform and removed the inconsistent spectra and the interference spectra.Wavelet-transform technique exhibited the local frequency of THz in different time locations.This technique would find applications in THz time-resolved spectroscopy.