High-order Harmonic Generation Of Model Li~+ With Two Color Fields

Thanks to prominent features that irreplaceable by traditional light sources,high intense laser was been used to studies of micro-substances especially atoms and molecules by a few visionary scientists after the technology of high-power emission was realized.Since then,the interaction features of intense laser field with atoms and molecules was been investigated deeply and widely,and later,many novel non-linear physic phenomena such as tunneling ionization,above threshold ionization and non-sequential double ionization was proved to may occur in this process.Because of matters under the extreme intensity of electromagnetic field when interaction was take place,the try of traditional perturbation theory was no longer successful to many of this novel phenomena and people must look for new methods to address this problems.One of most directly and effective way is understand its by use of the results of time dependent Schodinger equation which was solved directly.But it is only a few particular conditions is suitable for analysis methods,and the majority of problems that's more complex are still frustrated by this methods until now.While,the rapid development of computer science and technology make up this disadvantages,it makes us available for settle this high-order non-linear issues by means of solve Schodinger equation numerically accurately.In the phenomena of interaction process of intense laser field with materials,the emission of high-order harmonic generation arose many of interests of scientists and been studied deeply.High-order harmonic generation have some particular advantages,firstly,this spectrum contain some photon their wavelength is very small,it is the way to get well coherent XUV laser.Secondly,HHG span a broadband frequency range within a ultrashort time interval,thus an isolated ultrashort attosecond pulse can generated by superposing part of the harmonics,which the best way to use attosecond pulse to realize and control matter and investigate their nature.So far,coherent XUV laser and isolated attosecond pulse was made successfully experimentally,besides,it already applied to study ultrafast dynamic process of atoms and molecules.Owe to excellent properties above,HHG always take the first place of investigation and get many breakthroughs since it was discovered theoretically.Our work investigate the properties of HHG generated by simulating the interaction of Li+ with one and two color intense fields respectively,and get an isolated ultrashort attosecond pulse.The specific work as follows:First of all,we obtain the angular dependent parameters about accurate model potentials of Li+,meanwhile,initial wave function and the ground and each excited state's eigenvalues which are agree well with NIST atomic and molecular data table's are obtained by means of solve three dimensional stationary Schrodinger equation.Ni the next place,we analysis and investigate the HHG spectrum of Li+ interaction with IR and different two color fields respectively by solve time dependent Schrodinger equation by means of time dependent Pseudo-spectral method,Our results show that the strength of assisted XUV is not amplified during the harmonic generation process,but the yield of HHG power spectrum in whole plateau has a significant enhancement.Furthermore,the optimal time delay between the IR and XUV pulses allows the production of ultrabroadband supercontinuum spectra.By superposing some harmonics,a strong new single 27-attosecond ultrashort pulse can be obtained.