Strengthened Hyper-Raman Lines with the Coherent SuperpositionState

Abstract

High-order harmonic generations from a one-dimensional Coulombpotential atom are calculated with the initial state prepared as acoherent superposition between its ground and first excited states.When the energy difference of the two states is small, we can chooseproper laser pulse such that the first excited state can be excitedonly to other bound states instead of being ionized. We show thatonly the hyper-Raman lines are observable instead of the harmonics.The energy difference of the ground and the first excited state canbe deduced from the highest peak of the hyper-Raman lines. Wefurther show that the similar results can be obtained by using acombination of two laser pulses with different frequenciesinteracting with the atom initially at the ground state.