The spider structure in the photoelectron momentum distributions (PMDs) of ionized electrons from the hydrogen atom is simulated by solving the time-dependent Schrödinger equation (TDSE). We find that the spider structure exhibits sensitive dependence on carrier envelope phase (CEP) of the few-cycle pulses. To elucidate the striking CEP dependence of the spider structure, we select three physical parameters I L, I R, and I R/I L to quantitatively characterize the variations of the spider structure induced by altering the CEPs. I L is the sum of the left half panel of the transverse cut curves (i.e., the sum of all the negative momenta along the laser polarization direction), I R is the sum of the right half panel of the transverse cut curves (i.e., the sum of all the positive momenta along the laser polarization direction), and I R/I L is the ratio between the two sums. These parameters are shown to have monotonic relation with the CEP value, which is exploited to extract the CEPs. We anticipate that our method will be useful for obtaining CEPs encoded in the spider structure of PMDs.

No abstract

We present results of numerical simulations on the photoelectron momentum distributions of the p-orbital electrons of neon atoms ionized by a pair of time-delayed and oppositely circularly polarized intense laser pulses. Deploying the strong-field theory, we can readily produce vortex-shaped momentum distributions. Similarity and disparity in the vortex patterns between the neon and hydrogen atoms are observed. The optical Stark effect is found to induce distortions in the vortex momentum distributions, which are quantitatively described by introducing several physical quantities. Among these quantities, the autocorrelation parameter turns out to be the most sensitive probe for extremely weak Stark effect. The nonlinear phase induced by the optical Stark effect deciphers the distortions of the vortex momentum distributions.

Tunneling ionization of atoms is the basis of many phenomena and techniques, which requires people of a comprehensive understanding of this crucial physical process. Recent experiments have proved the existence of the nonzero initial longitudinal momentum spread at the tunnel exit. However, the initial longitudinal velocity was usually set to zero in the adiabatic regime. In this article, we numerically study the mapping of the initial longitudinal velocity to the spiderlike photoelectron momentum distributions in hydrogen atom by deploying the semiclassical rescattering model and the time-dependent Schrödinger equation. Nonzero longitudinal initial velocity, either an offset or an offset distribution, is considered in the semiclassical rescattering model. Longitudinal and transverse cut-plots of the photoelectron momentum distributions are employed for discussion. The final longitudinal momentum of the electron is found to be sensitive to the initial longitudinal velocity, which offers us a method of determining the information of the initial longitudinal velocity from a photoelectron momentum distribution according to this linear relationship. We unveil that either an offset or an offset distribution for the initial longitudinal velocity can perfectly reproduce the same spiderlike PMDs. The semiclassical results are backed by the full quantum simulation. It is anticipated that more precise investigation is mandatory in deepening the knowledge of the initial longitudinal velocity in strong field ionization of atoms.