Controlling XUV’s Harmonics Using Double IR Laser Pulses

Abstract

Achieving efficient control of electrons and nuclei in atoms and molecules with lasers has been a subject of great interest for decades, in Physics and in Chemistry. One of the current and challenging questions with the today advanced in laser technology is how to generate and characterize a single and or a train of attosecond (1 𝑎𝑠 = 10−18 𝑠) laser pulses likely to control electrons in molecules. This therefore demands a proper mechanism that can lead to easy control of the extreme ultraviolet (XUV) harmonics.This is addressed in this work by first irradiating the Hydrogen atom H with a single infrared (IR) pulse and later with simultaneous interaction with double replica IR lasers of intensity 2 × 1014W/cm2 each. The order of frequency of emitted photons in the recombination process for two IR Lasers and for a single IR laser, interacting with the hydrogen atom without time delay, were 400 and 278, respectively. This High Harmonic Generation (HHG) of XUV’s depends on laser atom interaction which is governed by Time Dependent Schrödinger Equation (TDSE) and the Strong Field Approximations (SFA). By varying the time delay between the two simultaneous IR pulses, controlled harmonics are produced. It turns out that these delays caused spectral shifts which are smaller for longer time delays (the spectral shift for 400 a.u. time delay is smaller than that of 1250a.u. time delay).