Role of intra-band transitions in photo-carrier generation

TL;DR

This paper theoretically explores how intra-band transitions significantly influence laser-induced photo-carrier generation across various photon energy regimes, highlighting their essential role in nonlinear excitation processes and potential for controlled carrier generation.

Contribution

It demonstrates that intra-band transitions are crucial for accurately describing photo-carrier generation in different regimes and reveals their role in enabling multi-photon excitation channels under strong laser fields.

Findings

Intra-band transitions enhance photo-carrier generation in multi-photon and tunneling regimes.

Intra-band transitions are essential for nonlinear photo-carrier processes.

Strong laser fields activate additional multi-photon channels via intra-band transitions.

Abstract

We theoretically investigate the role of intra-band transitions in laser-induced carrier-generation for different photon energy regimes: (i) strongly off-resonant, (ii) multi-photon resonant, and (iii) resonant conditions. Based on the analysis for the strongly off-resonant and multi-photon resonant cases, we find that intra-band transitions strongly enhance photo-carrier generation in both multi-photon absorption and tunneling excitation regimes, and thus, they are indispensable for describing the nonlinear photo-carrier generation processes. Furthermore, we find that intra-band transitions enhance photo-carrier generation even in the resonant condition, opening additional multi-photon excitation channels once the laser irradiation becomes sufficiently strong. The above findings suggest a potential for efficient control of photo-carrier generation via multi-color laser pulses through optimization of the contributions from intra-band transitions.