Metrology Of Terahertz Wavelength And Frequency Based On Interferometry

With the development and application of terahertz technology,the demend for terahertz parameter measurement is increasing.Frequency is one of the most important parameters of terahertz wave.Theirfore,it is very important to investigate the precise measurement method of terahertz frequency and to establish the measurement standard of terahertz frequency.The measurement of terahertz frequency based on terahertz frequency comb has very high precision,with which the measurement uncertainty can be down to 10-12.However,terahertz frequency comb is only suitable for measurement of terahertz with very stable frequency and very narrow linewidth.In order to expand the measurement ability of terahertz wavelength and frequency and realize a wide range of terahertz source measurements,we developed a terahertz interferometer to measure terahertz wavelength and frequency.The main work and research contents of this paper are as follows:(1)In this paper,based on Fabry-Perot interferometry and Michelson interferometry,we developed a Fabry-Perot interferometer and a Michelson interferometry,with which can measure the wavelength and frequency of a 94.5GHz instable sources and a 775 GHz BWO terahertz laser were successfully measured.(2)The program of interferometry based on Lab VIEW is used to control the precise displacement platform and realize the signal amplification and data acquisition based on the lock-in amplifier.(3)The measurement results of the Fabry-Perot terahertz interferometer and Michelson terahertz interferometer are traceable to the terahertz frequency comb.The calibration were performed at 100 GHz and 300 GHz with a frequency multiplier.The calibration procedure of the Fabry-Perot terahertz interferometer and Michelson terahertz interferometer are discribed.(4)The repeatability and stability of the Fabry-Perot terahertz interferometer and the Michelson terahertz interferometer were exprimentally investageted,and the measurement results were analyzed and the measurement uncertainty was budgeted.The difference of measurement results between the two interference devices is less than 0.3%,which can realize the measurement of unstable frequency terahertz wavelength and line width terahertz frequency,and expand the terahertz wavelength and frequency measurement capability.