Based On The Raman Scattering Of LiNbo₃ Crystals THz Radiation Mechanism And The Performance Of The Research

Terahertz(THz)electromagnetic wave(0.1～10THz)is the wavelength between millimeter waves and infrared waves,a fairly wide range of electromagnetic radiation zone.Compared to adjacent frequent bands optical and microwave technology,the understanding and use of THz are relatively little.However,with the development of exploration,some important significance and broad application prospects have been studied clearly.Also international academic community has drawn high attention in the THz.Now,the generation of terahertz technology,is still one of the main aspects of terahertz science and technology.Firstly,this paper introduce some characteristic,generation technology and appliance of THz.Secondly,we analyzed that a new elementary excitation—polariton,which formed coupling between the incident laser and the nonlinear crystal lattice vibration mode.We obtained dispersion characteristic curve and its physical significance via analyzing dispersion equation of polariton.We present that the dispersion characteristic curve of nonlinear crystal polariton is the physical basis of THz radiation by polariton.At the same time,this paper used first principles to analyze the Raman spectra of LiNbO3 crystals which were in line with the ideal chemical ratio,and obtained its intrinsic vibration frequency.Combined with the equation of polariton,the dispersion of nonlinear crystal LiNbO3 is presented.Through the analysis of the LiNbO3 crystal the equation of polariton,the dispersion curves,predicting that LiNbO3 crystal could radiate electromagnetic wave with the frequency range of 0～6.97 THz(0 cm-1～230 cm-1),and the band falls exactly in the terahertz range.Finally,this paper also combined with the related experimental results.We reseach the influence of structure defects caused by mixed with Mg to the raman spectrum of LiNbO3 crystal.Through analysis and comparison,we found out that the width of the raman spectral lines narrowed down 9 cm-1 and the raman scattering intensity enhancing the 1095 units by comparing the Raman spectra of crystal materials of whether mix Mg with LiNbO3 crystal.This result explains the results of that as the sample material is used to radiation THz wave the LiNbO3 crystal be mixed Mg can get more stable performance and lower laser power input.This job working for designing of terahertz radiation source based on LiNbO3 crystal and improving the terahertz radiation performance to make theoretical basis.