压缩真空中的三能级原子的自发辐射强场高次谐波时间特性的理论分析

对压缩真空与V型三能级原子的相互作用作了理论分析, 探讨了量子干涉效应对压缩真空中原子自发辐射的影响。当原子的上能级简并时强的量子干涉效应影响原子的定态和定态出射光谱, 使它们对原子的初态敏感。这种情况下, 压缩使谱线趋于关于压缩真空中心频率对称, 量子干涉使谱线趋于不对称。通过用单电子近似求解含时薛定谔方程, 用加窗傅里叶分析的方法, 分析了单原子产生的高次谐波的时间特性。理论分析表明, 基态粒子数消耗对不同级次谐波辐射的影响程度不一样; 谐波辐射随着入射激光场强度的增加会出现饱和; 随着谐波级次的增加, 谐波辐射越来越趋向于集中在更短的时间间隔内, 相应的线宽也随着谐波级次的增加而增加。

Spontaneous Emission from a Three-Level Atom in a Squeezed VacuumTime Profiles of High-Order Harmonic Spectra with High Intensity Laser Field

The interaction of a three-level V-typeatom with a squeezed vacuum is analyzed. The effect of quantum interference between decay processes from two upper levels on the spontaneous emission is studied. When the upper levels are degenerated, the strong interference has effect on the steady state of the atom and the spectrum of the fluorescent light, and results in the sensitivity to the initial state of the atom. In this case, squeezing results in the symmetry of the spectrum about the central frequency of the squeezed vacuum, but the interference results in the asymmetry of it.High-order harmonic spectra are obtained by numerically solving the one-dimensional time-dependent Schrodinger equation with single-active-electron (SAE) approximation. The time profiles of the harmonic spectra from a single atom are obtained through a Gabor analysis of the acceleration of the atomic dipole. The dependency of the different harmonics on the ground state population is investigated. It is shown that the harmonic yield tends to be saturated when driving laser is getting more and more intense, and that the harmonic radiation tends to be concentrated in a shorter interval when the harmonic order is getting higher, resulting in wider spectrum width.