The Propagation Properties Of Double High Order Gaussian Beams In Strongly Nonlocal Medium

When light transmitting, compression caused by self-focusing of medium offsets broadening caused by the diffraction of light, beam transverse section will never change during transmission,we call this kind of beam as spatial optical solitons. On the one hand, owing to the special transmission properties, there is a broad prospect of research on spatial optical solitons in information processing and transmission; On the other hand, the study on the spatial optical solitons provides guidance for the light switch. However, In recent years, the study on optical soliton is in the stage of single beam. With the development of science and technology and the depth of research strength, multi-polar vector solitons begin to attract many scholars attention. The novel properties of Vector soliton open up a new category for nonlinear optics, and will be effective to the development of all-optical devices. This paper mainly discusses the study on double Hermitian gaussian beam coupling in different nonlocal media, at the same time, the thesis also discussed super gaussian beams with gaussian response media, as follows:First, the concept and history of soliton are introduced; and series of solitons are introduced according to different conditions; finally, the research status of spatial optical solitons are introduced in nonlocal nonlinear medium.Second, based on nonlocal nonlinear Schrodinger equations of double beams, the evolutional rules of parameters and critical powers of transmission of orthogonal polarization center-coincidence double Hermite-Gaussian beams are calculated with variational approximation method in strongly nonlocal medium. The orthogonal polarization center-coincidence double Hermite-Gaussian spatial optical solitons and their large phase shifts evolutional rules are obtained when the two beams are incident with critical powers. The beams can form breathers when the two beams are incident with total critical power but two incident powers are different. For breathers of each order, the beam width with high power periodically compacted oscillate; the beam width with low power periodically extended oscillate. Moreover, the phase shift of higher power breather increases faster with the increasing of transmission distance. When the order of Hermite-Gaussian is under fifth order, the variational approximate solution agrees well with the numerical solution.After that, the propagation properties of two orthogonal polarized center-coincidence Hermite-Gaussian(HG) beams are investigated in strongly nonlocal medium with exponential-decay response using variational method. The evolutional equations for the parameters of HG beams and critical power Pc are obtained. The HG spatial optical solitons come into being when the two incidental powers are both equal to the critical power. However, when two beams are incident with total power 2Pc while the two incident powers are not equal, they form HG breathers. By means of numerical simulation, the beam with low order may haveapproximate soliton solution; when the orders of beams are higher than the third, there are no soliton solutions. By comparing variational solution with numerical solution we find that when the order of beams are under the third the variational solutions can well reveal the propagation properties of orthogonal polarization center-coincidence double HG beams in strongly nonlocal medium with exponential-decay response.Finally, the propagation properties of orthogonal polarization double super-Gaussian beam in strong nonlocal media are studied by variational approximation method and accurate numerical simulation. The variational method reveals that a similar SG vector solitary wave can be attained in strongly nonlocal medium when the total initial power is equal to the critical power and the ratio of the original widths between two beams is equal to a certain value which is decided by the orders of two beams. However, with the accurate numerical simulation, the research shows that in strongly nonlocal medium it's difficult to form rigorous SG vector soliton, only can form periodic vector solitary wave. What's more, with the order of SG solitary wave increasing, the phase shift increase quickly, and the error of two solutions will increase.