Using Multicycle Two-Color Field Getting A Isolated Attosecond Pulse Research Of Mechanism

In the21century, as a result of the rapid development of ultra-short and ultra-intense laser technology, the rapid development of fettosecond laser offers unprecedented practical means and development opportunities to research the ultra-fast phenomenon, but the infinite enthusiasm from exploring nature’s mystery drove people want to find the flash pulse shorter than fettosecond. So the laser technology got into a new field, to explore the science of attosecond pulse and measure it. In order to study the scale transient phenomenon of attosecond, it needs to explore all kinds of the techniques and methods.Once attosecond pulse achieved, it will have significant application prospect.In this thesis, We theoretically investigate the high-order harmonic and attosecond pulse generation by numerically solving the one-dimensional time-dependent Schrodinger equation from a hydrogen atom in a two-color laser field, By analyzing the compression mechanism of two-color electric field, we further enlarge the duration of the synthesized pulse to60fettosecond, and obtain a single160attosecond short pulse.This is the longest pulse duration used in obtaining single attosecond pulse so far.First of all, we contrast the single-color field and two-color field, found that we can get the isolated attosecond pulse in multicycle two-color field,Here the effect of synthesized pulses is similar to the effect of single5fs ultrashort pulse.The reality of this scheme greatly reduces the requirements for the pump laser system used traditionally for generating an isolated attosecond pulse,and it allows us to use a well-established conventional high-power pumping laser.Second,By analyzing the compression mechanism of multicycle synthesized pulse.Based on the mathematical representation of combination pulse electric field, and find two multicycle femtosecond laser pulses, then it show that when there are12Ti:sapphire optical cycles in the pulse envelope, by adding a suitable second optical field, the electric field of the synthesized pulse presents three-segments, and only amplitude of the electric field in middle segment makes a major contribution to the plateau and cutoff region of the harmonic spectrum.Finally, according to analyzing the compression mechanism of multicycle synthesized pulse and isolated attosecond pulse generation, sum up a rule, follow this rule to explore the the most ideal results and show the difference of getting results between the relative phase of that two fettosecond pulses.