Affiliation:
1. Laboratory of Molecular Reaction Dynamics, Liaoning University of Technology, Jinzhou, 121000, China
2. Department of Physics, Imperial College London, South Kensington Campus, SW7 2AZ, London, United Kingdom
Abstract
The chirp form selection for producing intense and broad high-order harmonic spectra has been investigated when the initial state is chosen to be the single or superposition states. It is found that, for the case of a single ground initial state, the down-chirp is much better for extending the harmonic cutoff with the stronger emission intensity. Moreover, the multi-color combined field is beneficial to produce the larger harmonic cutoff and higher harmonic intensity. After the control of laser waveform, the combination of 3-color down-chirps with a proper UV pulse is the best condition to obtain the intense X-ray spectral continuum and the isolated attosecond pulse. For the case of superposition initial state, both the up-chirp and down-chirp are beneficial to generate the high-intensity spectral regions. However, with the combination of multi-color field, only the harmonic cutoff can be further extended, and the harmonic intensity presents almost no changes for the superposition initial state case. Finally, by properly choosing the 3-color up-chirps or 3-color down-chirps combined pulses, the stronger intensity harmonic spectra covering the X-ray region can be obtained, which can produce the isolated pulses of 37 as.
Funder
Natural Science Foundation of Liaoning Province
Youth Project of Liaoning Education Department, China
Innovation Project of University Students
Publisher
World Scientific Pub Co Pte Ltd
Subject
Condensed Matter Physics,Statistical and Nonlinear Physics