Electron supercontinuum in ionization by relativistically intense laser pulses

TL;DR

This paper investigates how intense circularly polarized laser pulses ionize hydrogen-like ions, producing a controllable supercontinuum in photoelectron spectra influenced by relativistic effects and radiation pressure.

Contribution

It introduces a relativistic strong-field approximation analysis revealing controllable supercontinuum formation and angular asymmetries in ionization by intense laser pulses.

Findings

Broad supercontinuum regions in energy spectra without interference.

Control of supercontinuum via laser field intensity.

Asymmetry in polar-angle distributions due to radiation pressure.

Abstract

Ionization of hydrogen-like ions by intense, circularly polarized laser pulses is analyzed under the scope of the relativistic strong-field approximation. We show that, for specific parameters of the laser field, the energy spectra of photoelectrons present a broad region without interference (supercontinuum) which can be controlled by modifying the laser field intensity. The physical interpretation of the process is developed according to the Keldysh theory, emphasizing the importance of the complex-time saddle point contributions to the total probability of photoionization. The corresponding polar-angle distributions present an asymmetry attributed to radiation pressure effects.