Angle and time-resolved polarization change induced by Kerr effect in amorphous and crystalline SiO2

TL;DR

This study investigates the Kerr effect-induced polarization changes in amorphous and crystalline SiO2, revealing strong, angle-dependent polarization rotations and differences between material structures under intense light excitation.

Contribution

It provides the first detailed measurement of polarization changes induced by the Kerr effect in both amorphous and crystalline SiO2, highlighting their distinct behaviors.

Findings

Polarization rotation can exceed 90 degrees.

Polarization change depends on pump-probe angle, not crystal orientation.

Reflected and transmitted beams show different polarization behaviors.

Abstract

We measure the polarization change of a beam reflected from the surface of both crystalline alpha and amorphous SiO2 samples while they are photo-excited by an intense light pulse, at intensities above the nonlinear excitation threshold yet below the damage threshold. The polarization change varies with the angle between the polarization of pump and probe light, but is found to be independent of their orientation relative to the crystal axes. This behavior differs between the reflected and transmitted beams, and can be modeled by taking into account a birefringence induced by the electric field of the pump. These polarization-change effects can be very strong, with polarization rotation exceeding 90{\deg}, at pump intensities well below the damage threshold. We also observe a markedly different behavior of the reflected beam depending on whether the material is crystalline or amorphous.