The Quantum Of The Laser Pulse Shaping And Coherent Control

Since the Laser has been emerged, nonlinear optics have been made faster progress. In the mediums, an increasing researchers were inspired a variety of wonderful optical effect caused by femtosecond and attosecond laser ultra-short pulse. Because of the nonlinear optical effects related domain is widespread, based on this, which is very promising. At present, the interaction between the light and materials becomes to be a compelling research topic. Interaction between light and sample is determined by the physical mechanism of nonlinear effect, essentially the action of intrinsic microcosmic dynamics behavior of quantum system. Nonlinear optics provides theoretical basis for the research about the control of the optical properties of the materials and improvement of the application efficiency of laser. As the human more profound understanding of the structure of microscopic particles, all kinds of experimental results of material's nonlinear optical properties has been gotten the actual application of numerous domains. The microstructure of the substance is very complicated, theoretically it is very difficult to strictly study about interaction between the light and particle and get the exact result, therefore, we simplify structure of quantum systems by adopting some assumptions and approximation methods. The propagation of optical Pulse in the nonlinear optical materials are accurately descried through using the Maxwell-Bloch equation.In the research process about the Optical pulse propagation of nonlinear samples, we have found some wonderful microscopic kinetics characteristics such as self-induced transparency and pulse splits,etc, explained by through McCall Hahn area theorem. When incidence weaker pulse and smaller area (less thanπ), pulse area of the sample can change. under the role of spectral manipulation of the atomic line width resolution region caused by the Resonance samples, the envelope of small area optical pulse electric field starts oscillation according to cosine rule, thus pulse area become exponential decay as pulse lasting change, which the dynamic behavior can hardly affect to total energy of pulse. From the macroscopic view, this is a kind of dispersion effect caused by absorption spectral lines, that's to say, it is a natural phenomenon of pulse shaping. This shaped effect can cause periodic changes of excited state distribution of single photon absorbtion process and lead to strong instantaneous oscillations.Using the shaped optical pulse caused by this dynamic factors within coherent control domain has become a burgeoning research trend.Based on the above thoughts,this paper is carried on the theoretical research about propagation of the weak laser pulse in the resonance materials, as the half-classic quantum theory a the tool and according to the area theory. Seen from reasoning theory results, the shape of pulse related with some parameters such as the medium length, frequency of incident field and relaxation time of atoms. When the resonance materials (Rb atomic system) is excited by a small area shaped pulse, transition distribution of the two-photon excited state was manipulated by the shaped pulse.Theoretically, Our study found that through the modulation of some parameters such as length of sample, bandwidth of input pulse and relaxation time of Rb atoms, we can get the small area pulse light of different shapes.This shaped pulse have remarkably role for probability distribution of two-photon excited state, meanwhile appearing periodic oscillation phenomena of probability amplitude. Two-photon excited signal peak will be effectively strengthened and oscillation phenomena of probability amplitude increased obviously with the increase of△ωand T as well as decrease of (?), but the number of oscillation have been reduced in the certain period, which these effects are modulated by incident pulse shape. Although the results have been gotten through only theoretical research, we must believe that, these achievements can provides the reliable theory foundation for the experimental research and application of the related domain of the pulse shaping and coherent control and other fields.