Method and device for measuring complex refractive index of sample based on terahertz band

Abstract

The invention discloses a method and device for measuring the complex refractive index of a sample based on a terahertz band, and relates to the technical field of laser. The method comprises steps ofdetermining a measured value of the complex reflectivity of the sample according to the reflected signal of a terahertz pulse on the surface of the sample and the reflected signal of the terahertz pulse on the surface of a metal mirror; determining a model estimated value of the complex reflectivity of the sample according to a reflectivity calculation model, and constructing a cost function according to the measured value of the complex reflectivity and the model estimated value of the complex reflectivity, wherein the reflectivity calculation model considers the influence of the complex refractive index of the metal mirror on a reference signal and the phase error during the measurement, the model estimated value of the complex reflectivity of the sample is represented by a plurality ofparameters; optimizing and solving the cost function, and determining the complex refractive index of the sample according to the optimized solution result. Through the above steps, the method can accurately determine the complex refractive index of the sample, and is especially suitable for the complex refractive index measurement of a high-reflectivity material.

Description

technical field [0001] The invention relates to the field of laser technology, in particular to a method and a device for measuring the complex refractive index of a sample based on a terahertz frequency band. Background technique [0002] Terahertz waves generally refer to electromagnetic waves with wavelengths ranging from 30 microns to 3 mm and frequencies ranging from 0.1 THz to 10 THz. Terahertz waves are between infrared and millimeter waves, and have a fairly wide spectrum. Terahertz waves are in the transition region between photonics and electronics, and can provide information that traditional detection methods such as visible light or microwaves cannot provide, so it has great application prospects in the fields of physics, chemistry, and biomedicine. [0003] Terahertz time-domain spectroscopy is a very important and widely used technology. The main principle of this technology is: first mix the terahertz pulse and the sampling detection pulse in the detector, ...

AI Technical Summary

Problems solved by technology

[0009] The technical problem to be solved by the present invention is to solve the technical problem that the existing complex refractive index measurement method has low measurement accuracy, and is especially unsuitable for complex refractive index measurement of high reflectivity materials (such as metals)

Images