The Propatation Of 1D And 2D Optical Spatial Solitons In Photorefractive Media

In nonlinear media, when self-focusing effect induced by the nonlinear response of the media to the light balances the diffraction, the beam becomes self-trapped at a very narrow width and does not spread in the transverse direction, and are called spatial solitons. They have been demonstrated to exist in a variety of nonlinear medium, and exhibit a richness of phenomena such as fusion, fission, annihilation, and stable orbiting etc. This is very important for spatial solitons in future data transmission and processing schemes. This paper has mainly studied the propagation performance of one dimensional and two dimensional optical spatial solitons by using finite difference method and Alternating Direction Implicit(ADI) difference method respectively. The so-called dimensional index for the horizontal direction. Combined theoretical analysis and numerical simulation diagrams, The contents and achievements are outlined as follows:1. A low amplitude one-dimensional screening bright soliton would present linear diffraction in a homogeneous medium without lattice, while in the anisotropic nonlinear area, if we don’t take the diffusion effect into account, the input beam would keep shape and be a line in the transmission direction, if we considerate to it, the beam would be self-bending, what’s more,the direction and degree of self-deflection are related to the temperature. When induced a defect photonic lattice into the photorefractive crystal, by changing the applied electric field strength and the ratio of the lattice depth with the intensity of input beam, we can found that the positive and negative defect lattice all can support defect modes.2. The vortex beam would decay into the fundamental solitons in a nonlinear medium, and the number of the fundamental solitons is twice of the order number of the vortex soliton. When a charge-1 vortex beam propagation in a positive defect lattice,with a certain ratio of the lattice depth and the intensity of input beam, we can get a stable one-charge vortex soliton. A charge-2vortex beam is incidented to a negative defect lattice,with appropriate values, a similarquadrupole can be obtained in the exit surface, and the energy all keep in the defect site. What is more important, it’s phase don’t keep the initial spiral structure, but the diagonal points have the same phase, the adjacent points have opposite phase, it’s not stable. By changing the applied electric field strength and the ratio of the lattice depth, we can receive stable defect modes.3. We inject a Gaussian beam into the bessel optical lattice, with different initial input conditions in the case of lattices, the input beam can overcome these effects and form a ringshaped soliton or a circle- shaped soliton, and the energy distribution in the lattice channel is different.