Numerical Simulation Of High-Order Harmonic Generation From Solids Under One-Dimensional Periodic Potential Condition

During the interaction between the laser and matters,the high-order harmonic generation has been considered as the most promising method to produce attosecond pulses.The attosecond pulse can be used to detect and control the ultrafast electron motion,and then it promotes the development of attosecond science.Compared with the atomic and molecular systems,solid materials have the characteristics of high density and periodicity.With the interaction of external laser field,solid materials have the potential advantages to improve the harmonic efficiency.Therefore,the related dynamics about the harmonic emission from the solid has become one of the hot topics in strong field physics.In this thesis,one-dimensional periodic potential is employed as the theoretical model to simulated the solids.By solving the time-dependent Schr(?)dinger equation under the length gauge,the electron dynamics is investigated in the high-order harmonic generation process from solids,which mainly contains two aspects as follows:(1)Electron dynamics in the high-order harmonic generation from the monochromatic periodic potential in the chirped laser field.The high-order harmonic generation from the monochromatic periodic potential is numerically simulated by solving the one-dimensional time-dependent Schr(?)dinger equation in the chirped laser field.Combining the quasi-classical model with the electron population of each energy band and the time-frequency distribution,the physical mechanism of the high-order harmonic generation from the monochromatic periodic potential in the chirped laser field is revealed.The multiple channels contributing to the harmonic generation are distinguished.Moreover,the chirped pulse is proposed to manipulate the channels.(2)The electron dynamics in the high-order harmonic generation from the bichromatic periodic potential.Based on the time-dependent Schr(?)dinger equation,the difference between the harmonic generation from the monochromatic periodic potential and the bichromatic one is revealed.The combination of the static electric field and the trapezoidal field is proposed to enhance the harmonic efficiency of the second plateau for the bichromatic periodic potential.By adjusting the symmetry of the bichromatic periodic potential,the harmonic emission of the second plateau is mainly contributed by the single quantum channel.Moreover,the appearance of harmonic spectral minimum for the bichromatic periodic potential is closely related to the electron transition between the third conduction band and the first conduction band.