Pushing Multiphoton Resonant Ionization Of Argon To Low-intensity Regime And The Fabrication Of High Harmonics Generation In Optical Waveguide

In recent years,the emergence of ultrafast laser has greatly promoted the study of the interaction between light and matter,especially the emergence of high order harmonics generation(HHG),which finally promoted the generation and rapid development of attosecond physics.Resonance-enhanced multiphoton ionization process of argon atom by 800 nm,30 fs linearly polarized laser field is investigated at an intensity range from 1.1 to 4.55 × 1013W/cm2.At 4.55 × 1013W/cm2 intensity the experimental photoelectron energy spectrum is in a good agreement with the time-dependent Schrodinger equation(TDSE)calculation where the double structure originating from dressed 4p-4d coupled transition are clearly identified.From the spectrum,it is shown that the pulse duration can obviously influence the resonant ionization yield.At lower intensity of 1.1 × 1013W/cm2,the resonant ionization process via 4f state is observed,however,the expected peak(jet)at 90 degrees in the photoelectron angular distribution,from the zeroth order above threshold ionization,has completely vanished.Such behavior is due to the destructive interference phenomenon in the coherent contributions of different partial waves of the phoelectron namely,ed and eg photoelectron states,and has been confirmed in our TDSE calculations.The second work of this paper is to generate ultra-short XUV pulses using the HHG scheme:higher energy photons,are obtained by upgrading the XUV light source,which lays the foundation for the study of the electron dynamical evolution in the inner shell.In the process of XUV source upgrade,a Ti:sapphire of the secondary amplification platform was replaced and pump source was installed as well,resulting that the single laser pulse energy with central wavelength of 800 nm was greatly promotional.The optical parametric amplifier(OPA)was debugged and installed,thus the conversion of wavelength from 800 nm to 1300 nm is successfully realized.The result is that XUV photons has a flux of greater than 107 photons/s with energy larger than 200 eV based in the He gas,which is optimal for this technology.