Laser-Induced Above-Bandgap Transparency in GaAs

TL;DR

This paper demonstrates significant laser-induced above-bandgap transparency in GaAs at room temperature, attributed to a laser-induced blue shift of the band edge, with simulations supporting the dynamic Franz-Keldysh effect as the underlying mechanism.

Contribution

It provides the first experimental observation of large above-bandgap transparency in GaAs caused by ultrafast laser pulses and models this effect with the dynamic Franz-Keldysh effect.

Findings

40% laser-induced transparency observed

Transparency occurs only during laser pulse

Band edge shift explained by ponderomotive potential

Abstract

We report the observation of large ($\sim 40%$) laser-induced above-bandgap transparency in GaAs at room temperature. The induced transparency is present only during the pulse width of the driving midinfrard laser pulses and its spectral shape is consistent with a laser-induced blue shift of the band edge. Our simulations based on the dynamic Franz-Keldysh effect reproduce the salient features of the experimental results, demonstrating in particular that the amount of the band edge shift is approximately given by the ponderomtive potential.