Broadband Fourier Transform Terahertz Spectroscopy And Research.

Terahertz(THz)is the electromagnetic wave between the microwave and the infrared wave.At present,there are some materials band has a unique spectrum in THZ band.Benefit for it,the THz technology has broad applications in non-destructive,space physics,material science,diagnosis,communication and military.It is a key tool to carry out these researches and it has important sense to investigate the THz wide spectrum technique.In this work,based on the Fourier transform(FT)spectrum principle,the wideband THz FT spectrum measurement system with mercury lamp as light source and Michelson interferometer as the basic light path is built.The main contents of the paper is as follows:(1)The system composition of the THz FT spectrometer based on the Michelson interferometer is studied firstly.The spectrum resolution,sampling distance and sampling interval are analyzed based on the basic principle,which will provide the theoretical guidance in the experimental works.(2)Theoretical model of the THz FT spectroscopy measurement is built up.Based on the model,the maximum divergence angle of the incident light into the Michelson interferometer and the maximum tilt angle of moving mirror are analyzed.It will provide theoretical basis for the collimation of THz source and control of moving mirror.(3)The wideband THz beam-splitter with the super thin metal film structure supported by polyester film is proposed.The theoretical beam-splitter model is built up based on the transmission matrix theory.Based on this theory result,the device of the wideband THz beam-splitter based on Cr thin film is fabricated and experimentally demonstrated,which will act as the key device in the system.(4)The wideband THz FT spectrum system is built at last.Based on LabVIEW,the synchronization program of motion control of the moving mirror and data acquisition is finished.With the key devices,the whole optical system is finished.The preliminary experimental results indicate that the THz spectrum from 0.1 to 10 THz is obtained in our system,which already covering the whole THz band.