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

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• Coherent control
• Light propagation, transmission & absorption
• Semiconductors