The Propagation Characteristics Of Second-order And Higher-order Complex Solitons In Strongly Nonlocal Media

Gaussian beam usually appears in the form of laser,while laser beam usually exists in the form of optical soliton(such as Gaussian beam)in nonlinear medium.We mainly study the propagation characteristics of beams in strongly nonlocal nonlinear media.The propagation of light beam is closely related to the medium refractive index distribution in the propagation process.And the characteristics of the nonlocal nonlinear medium we studied are just related to this.It means the refractive index of a point in the medium is not only related to the light intensity of the point,but also related to the light intensity of other surrounding points,which just makes up for the deficiency of the previous local nonlinear medium.Therefore,in this medium,many new solitons transport models have been developed,which is of great significance.In this paper,we study the propagation characteristics of second-order and higher-order solitons in strongly nonlocal nonlinear media.The main contents of this paper are as follows:Chapter 1: It mainly introduces the history and current development of optical solitons,as well as the background and progress of nonlocal nonlinear media.Chapter 2: It mainly discusses the evolution of mixed solitons in strongly nonlocal media.By deducing the transmission formula of the mixed soliton,the evolution of the axial intensity,second-order moment beam width,critical power and curvature radius of the soliton are further analyzed.It is found that the evolution law of solitons is periodic and is related to the incident power and the parameters of the beam.According to different incident power,the light intensity on its axis will appear in three different situations.On the contrary,solitons will show three different changes according to different parameters during transmission.Chapter 3: It discusses the transmission characteristics of astigmatic composite solitons in strongly nonlocal media.From the initial expression of the astigmatic composite soliton,it can be found that at the initial position,the propagation pattern of solitons can be divided into three different cases: oval type,two-petal type and four-petal type.We further derive the beam transmission expression,and solve the analytical expressions of the intensity,beam width,power and curvature of the soliton.And through numerical simulation form,we made this series of analytic graph,and carried on the necessary elaboration.Among them,we describe the transmission graph of the soliton and discuss its characteristics in detail.Chapter 4: It discusses the evolution of higher-order mixed solitons in strongly nonlocal media.In this chapter,the transmission formula of higher-order solitons and the axial light intensity are derived.In addition,the variation of second-order moment beam width,critical power and radius of curvature are plotted by numerical simulation in the form of fourth-order solitons.However,the difference between higher-order solitons and second-order solitons is that the correlation factor at the critical point in the transmission process is different from that at the second-order solitons,which is no longer ? = 1.The evolution of the axial light intensity is also different from that of the second-order mixed solitons.Chapter 5: It mainly discusses the summary of the paper.