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

Abstract

The invention discloses a method and a device for measuring the complex refractive index of a sample based on a terahertz frequency band, and relates to the field of laser technology. Among them, the method includes: determining the measured value of the complex reflectance of the sample according to the reflection signal of the terahertz pulse on the surface of the sample and the reflection signal on the surface of the metal mirror; determining the model estimated value of the complex reflectance of the sample according to the reflectance calculation model, and according to The measured value of the complex reflectivity and the model estimated value of the complex reflectivity construct a cost function; wherein, the reflectivity calculation model takes into account the influence of the complex refractive index of the metal mirror on the reference signal and the phase in the measurement process error, the model estimated value of the complex reflectivity of the sample is expressed based on multiple parameters; the cost function is optimized and solved, and the complex refractive index of the sample is determined according to the optimized solution result. Through the above steps, the complex refractive index of the sample can be accurately determined, which is especially suitable for the measurement of the complex refractive index of high reflectivity materials.

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 technique. The main principle of this technology is: first mix the terahertz pulse and the sampling detection pulse in the detector, a...

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)

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