Temporal And Spatial Optical Solitons In The Cold Medium

Nonlinear optical phenomena in the cold atomic medium have attracted the at-tention of physicists. The research of temporal and spatial optical solitons ( such asultraslow optical solitons, ultraslow bistable optical solitons, vortex optical solitons,vector optical solitons, etc. ) in the cold atoms medium is very meaningful, whichaims to study the new nonlinear phenomena induced by quantum coherence in the in-teraction system of the cold atomic medium and optical wave, in particular target forthe phenomena that light speed is about the ten thousandth in the vacuum and thewave form is undistorted. These phenomena not only are conducively to understand-ing and mastering the new coherent nonlinear optical properties but also benefit tothe storage, extraction, and transmission for optical information ( including quantuminformation ), all-optical computer, optical switche, optical communication, e?cientrouter, hight precision nonlinear spectroscopy, and quantum entanglement. As faras we know, such studies are very few up to now, which belong to the forefront oftheoretical physics and its cross-cutting science.This thesis studies the related properties of temporal optical solitons ( ultraslowoptical solitons and ultraslow bistable optical solitons ) and spatial optical solitons (bistable optical solitons and vortex optical solitons ) in the cold atomic medium withdi?erent level structures. The main content is as follows:1) First, the relevant background knowledge of temporal and spatial optical soli-tons in the cold atomic medium is given. This includes the brie?y review of thedevelopment of temporal and spatial optical solitons, presentation of basic propertiesand solutions of temporal and spatial optical soliton's wave equations, and introduc-tion of the physical mechanism of electromagnetically induced transparency ( EIT )e?ect and related theory. The three preceding chapters of this thesis are the intro-duction of background knowledge.2) Next, the ultraslow temporal optical solitons and bistable temporal opticalsolitons in a lifetime-broadenedΛ-type three-state atomic system interacting with a strong control field and a probe field are discussed, which is the fourth chapter.As we demonstrate, ultraslow temporal optical solitons and bistable temporal opticalsolitons can exist in above cold atomic medium because of the equilibrium betweennonlinear e?ect and group velocity dispersion. By parameter control, such as theselection of appropriate control field intensity and single-photon detuning, di?erenttypes of temporal optical solitons can be very easy to be achieved. In addition, weanalyse the stability of bistable temporal optical soliton solutions and find them maystably exist in our inspection system.3) Finally, spatial optical solitons, bistable spatial optical solitons, and vortexspatial optical solitons in the lifetime-broadenedΛ-type and ladder-type three-stateatomic systems are studied, respectively. We find that these kinds of spatial opti-cal solitons can exist in above three-state atomic medium because of the equilibriumbetween nonlinear e?ect and di?raction property. Through the selections of the ap-propriate control field's intensity and single-photon detuning, we can easily realize thedi?erent types of spatial optical solitons. Meanwhile, we investigate the correspond-ing stability of bistable spatial optical solitons and vortex spatial optical solitons.By analysis, we get that the solutions of bistable spatial optical solitons and vortexspatial optical solitons are stable in above systems.The parameters we take here are all experimental parameters, so we believethat temporal and spatial optical solitons can be observed experimentally in thedi?erent types of three-state cold atomic medium. This work can provide otherresearch opportunities in nonlinear optical experiments and may result in a substantialimpact on technology.