Multi-photon schemes for mid-infrared detection

TL;DR

This paper theoretically compares multi-photon absorption and current injection in GaAs and GeSn alloys for mid-infrared detection, finding GeSn's superior nonlinear response in certain conditions.

Contribution

It introduces a comparative analysis of two-photon absorption and current injection schemes in GaAs and GeSn alloys for mid-infrared applications, highlighting GeSn's enhanced response.

Findings

GeSn alloys show larger nonlinear response than GaAs in certain mid-infrared conditions.

Two different pump schemes are analyzed for their effectiveness in photon absorption.

GeSn's response is significantly larger at specific alloy compositions and pump energies.

Abstract

We calculate the theoretical non-degenerate two photon absorption and three color injected current response tensors for bulk GaAs and Ge$_{1-x}$Sn$_x$ for a range of alloy compositions. In particular, by including a ''pump'' beam we compare two ''schemes'' that are sensitive to mid-infrared photons. In ''scheme I'' we consider GaAs and a pump photon with energy greater than half the band gap, and in ''scheme II'' we consider Ge$_{1-x}$Sn$_x$ with a pump photon with energy less than half the band gap. We find that for certain pump and alloy concentrations Ge$_{1-x}$Sn$_x$ has a substantially larger nonlinear response and three-color injected current than GaAs in the mid-infrared frequency window where both materials can absorb photons via non-degenerate two-photon absorption.