Exploration of Below-Threshold Harmonic Generation Mechanisms of Cesium Atoms in Intense Mid-Infrared Laser Pulses

Abstract

We present a non-perturbative quantum study of high-order harmonic generation (HHG) of Cesium atoms in intense mid-infrared laser pulses. An accurate angular-momentum—dependent model potential is constructed for the high-precision description of the Cs atom electronic structure. The three-dimensional time-dependent Schrodinger equation is solved accurately and efficiently by means of the time-dependent generalized pseudospectral methods (TDGPS) [Tong and Chu, Chem Phys 217(2–3), 119–130 (1997)].Besides the expected odd harmonics, the calculated HHG power spectra show additional structures due to the strong 6s–np couplings. The spectral and temporal characteristics of the HHG are further explored through the wavelet transformation [Tong and Chu, Phys Rev A 6102(2), 21802 (2000)]. As a result, we can investigate the prevailing mechanisms in different energy regimes, especially those contributing to the below- and near-threshold harmonics [Power et al., Nat Photon 4(6), 352–356 (2010); Soifer et al., Phys. Rev. Lett. 105(14), 143904 (2010); Yost et al., Nat Phys 5(11), 815–820 (2009)].KeywordsTime ProfileWavelet TransformationGroup DelayEnergy RegimeCesium AtomThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.