Ensemble properties of charge carriers injected by an ultrashort laser pulse

TL;DR

This paper investigates how ultrashort laser pulses alter the effective mass of charge carriers in dielectrics and semiconductors, revealing significant changes in optical properties and birefringence related to excitation mechanisms and carrier concentration.

Contribution

It provides a theoretical analysis of the laser-induced change in effective mass and optical response, highlighting the role of excitation mechanisms and carrier density in dielectrics like diamond.

Findings

Effective mass increases with tunneling excitation.

High carrier concentration influences optical and transport properties.

Excitation-induced birefringence can be significantly enhanced.

Abstract

The average effective mass of charge carriers produced by an intense ultrashort laser pulse in a transparent solid increases significantly as the excitation mechanism changes from multiphoton transitions to interband tunneling. We theoretically investigate this phenomenon for several dielectrics and semiconductors. For diamond as a representative dielectric, we present a detailed analysis of the laser-induced change of optical properties. When the concentration of free carriers is high, we find that the average effective mass controls not only the intraband charge-carrier transport but also the interband contributions to the optical response. We observe that the excitation-induced birefringence is particularly large for parameters where the plasma response compensates for the linear response of an unperturbed solid.