Nonlinear optical anisotropy due to freed electrons

TL;DR

This study computationally investigates the microscopic nonlinear optical anisotropy caused by freed electrons in atoms after non-resonant excitation, revealing transient birefringence effects within femtoseconds.

Contribution

It introduces a simulation approach to quantify nonlinear optical anisotropy at the atomic level following strong-field excitation.

Findings

Birefringence ratios of approximately 0.78-0.9 observed

Transient anisotropy persists for tens of femtoseconds

Simulation results provide insight into ultrafast optical responses

Abstract

We present a computational study of the pump-probe response of a single atom to assess any microscopic nonlinear optical anisotropy due to freed electrons for non-resonant optical excitation. Using simulations of the Schr\"odinger equation for an atom exposed to a strong, short-duration linearly polarized pump, we calculate the induced dipole moment along probe directions parallel and perpendicular to the pump polarization. Our simulations show birefringence ratios of approximately 0.78-0.9 on the timescale of tens of femtoseconds following the excitation pulse.