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Journal of Physics B Atomic Molecular and Optical Physics

Comparison of pulse chirping effects in single-photon versus two-photon resonant atomic ionization

Zhaopeng Sun, Jing Han, Wenkai Zhao, Chuan‐Lu Yang, Hongbin Yao

Published Jul 24, 2026• 0 citations
Publisher

Abstract

Abstract The effects of pulse chirping on the excitation and ionization process in hydrogen atoms are theoretically investigated by numerically solving the full time-dependent Schrödinger equation with a pseudospectral method. We specifically compare the dynamical results of single-photon resonant ionization (SRI) and two-photon resonant ionization (TRI) across laser intensities ranging from 10 12 to 10 14 W cm 2 . The ionization probabilities of SRI and TRI tend to exhibit opposite chirp dependent behaviors as the laser field changes from weak to strong, which are elucidated with the strong field approximation theory. Furthermore, the sensitivity of ionization probability to chirp can be suppressed at specific laser intensities when the laser field is synthesized by two-color resonant chirped pulses. Our study provides a basis for theoretical investigations into chirp effect on atomic photoionization, offering new insights into the coherent control of electron dynamics.

DOI
10.1088/1361-6455/ae9019

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In general cases of strong field excitation, the Stark effect has a significant influence on transient two-photon transitions, and the analytic description of this process is quite challenging. By combining analytical solutions and numerical simulations, the transient two-photon transition processes excited by weak and strong chirped pulses are systematically investigated, showing the important influences of parameters such as light field intensity, chirp factor, and detuning on the time-domain evolution of two-photon transition probabilities. Firstly, an approximate analytical expression is derived for the amplitude of the time-domain two-photon transition probability by using the second-order perturbation theory. This analytical solution indicates that the transient two-photon transition process under weak field excitation is similar to the Fresnel rectangular edge diffraction effect. As the light field intensity increases, the influence of the Stark effect on two-photon transitions also intensifies. Secondly, through a series of approximations, the approximate analytical solutions of the Schrödinger equation under strong field interactions are obtained. The analytical solutions show that the strong field Stark effect induces energy level to split, which disrupts the symmetry of the time-domain two-photon transition probability distribution, and its frequency domain process is similar to the “double-slit interference” effect. The research results indicate that the efficiency of population transfer during strong field excitation is closely related to the light field intensity, while the chirp factor can not only regulate the efficiency and time position of population transfer but also change the oscillation frequency of the population probability in the time domain. This work offers new insights into describing the time-domain evolution of the population probability under strong field excitation and lays a scientific basis for research on two-photon microscopy imaging.
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