Determination Of The Nonlinear Refractive Index In Nonlocal Nonlinear Media By Z-scan Technique

The rapid advances of optical communication technology have made the realizationof the wave-guide transmission of the weak signal and the full-light structure becomemore and more easy.The solition transmission in nonlocal nonlinear media supports thewave-guide transmission of the weak signal,that is helpful to the realization of the full-light structure.When the nonlinearity balances the diffraction,the beam transmttted inthe nonlinear media will transmit as spatial soliton.Therefore the study of the nonlocalnonlinear property has been a focus of the scientific research.In this thesis we study the determination of the nonlinear refractive index and thenonlocality of the nonlocal nonlinear media by theoretical method and the numericalsimulation. The thesis is composed of 5 chapters, among which, Chapter 1 is a survey,Chapter 2, 3, 4 are the introductions of our own work, Chapter 5 is a conclusion. Thethesis is structured particularly as follows.Chapter 1:The recent advances in the research of optical beam propagating in non-local nonlinear media are introduced.Chapter 2, the Z-scan technique for determinating the nonlinear refractive index ofthe nonlocal nonlinear media is introduced in detail by both the analytical method andthe simulation technique, it is concerned with the effects on the Z-scan curves madeby the change of the degree of nonlocality. And so the method of determinating thenonlocality and the nonlinearity is gottten. The adjustment brought by the degree ofnonlocality discussed and some feasible measurements is advised.Chapter 3,The basic idea is to achieve the nonlocal nonlinear response and theexpression of the nonlinear refractive index of the nematic liquid crystal.It is analyzedthe Z-scan method in detail when the sample is selected as nematic liquid crystal.Andthe method to measure the nonlinear refractive index of the nematic liquid crystal isfound.Chapter 4,It is devised the the experimental setup to measure the nonlinear refrac- tive index of the nematic liquid crystal. The detailed experimental steps is introducedand the some suggestion is showed.Chapter 5, In summary.The main achievement of the paper is that the Z-scan technique that determinatesthe nonlinear index is introduced and the effect Of the degree of nonlocality on the Z-scancurves is found.The nonlinear response in NLC is achieved. The method of measuringthe nonlinear index of NLC is obtained.