Coherent Features of Resonance-Mediated Two-Photon Absorption Enhancement by Varying the Energy Level Structure, Laser Spectrum Bandwidth and Central Frequency

摘要

The femtosecond pulse shaping technique has been shown to be an effective method to control the multi-photon absorption by the light-matter interaction.Previous studies mainly focused on the quantum coherent control of the multi-photon absorption by the phase,amplitude and polarization modulation,but the coherent features of the multi-photon absorption depending on the energy level structure,the laser spectrum bandwidth and laser central frequency still lack in-depth systematic research.In this work,we further explore the coherent features of the resonance-mediated two-photon absorption in a rubidium atom by varying the energy level structure,spectrum bandwidth and central frequency of the femtosecond laser field.The theoretical results show that the change of the intermediate state detuning can effectively influence the enhancement of the near-resonant part,which further affects the transform-limited (TL)-normalized final state population maximum.Moreover,as the laser spectrum bandwidth increases,the TL-normalized final state population maximum can be effectively enhanced due to the increase of the enhancement in the near-resonant part,but the TL-normalized final state population maximum is constant by varying the laser central frequency.These studies can provide a clear physical picture for understanding the coherent features of the resonance-mediated two-photon absorption,and can also provide a theoretical guidance for the future applications.