Method for measuring complex refractive index of terahertz material based on frequency spectrum

Abstract

The invention discloses a terahertz material complex refractive index measurement method based on a frequency spectrum. The method comprises the following steps: measuring a sample by using a frequency spectrum measuring instrument, and obtaining a frequency transmittance T (f) and a time domain reflection characteristic t (tau) on a discrete frequency spectrum based on measurement data; representing the frequency transmittance T (f) in the form of Fabry-Perot interference (FP interference), and obtaining tau 0 on the basis of the time domain reflection characteristic t (tau); defining a Gaussian function g (tau, tau 0) and a frequency spectrum G (f, tau 0) corresponding to the Gaussian function g (tau, tau 0); processing the frequency transmissivity T (f) based on the Gaussian function g (tau, tau 0) to obtain an updated spectrum transmissivity T'(f, tau 0); obtaining a local maximum (minimum) group number m and a complex refractive index real part n based on the processed spectrum transmissivity, and calculating to obtain an initial phase phi; and calculating an imaginary part k of the complex refractive index according to a Kramers-Kronig relationship to obtain the complex refractive index and absorbance of the sample.

Description

technical field [0001] The invention relates to the field of material measurement. Specifically, it relates to a spectrum-based method for measuring the complex refractive index of terahertz materials. Background technique [0002] Many materials can exhibit different characteristics in the terahertz frequency band than in the microwave frequency band, and have many new application potentials that have yet to be developed. However, the current measurement methods for material properties in the terahertz frequency band are not perfect, and the methods used are mainly based on continuous wave spectrum technology, which is difficult to achieve the high resolution and high sensitivity that have been achieved in the microwave frequency band. When measuring materials in the terahertz frequency band (especially solid materials), the surfaces of the material samples to be tested must be parallel, and Fabry-Perot interference (FP interference) will occur between the front and rear s...

AI Technical Summary

Problems solved by technology

However, the current measurement methods for material properties in the terahertz frequency band are not perfect. The methods used are mainly based on continuous wave spectrum technology, and it is difficult to achieve the high resolution and high sensitivity that have been achieved in the microwave frequency band.

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