Mid infrared two-photon absorption in a room-temperature extended-wavelength InGaAs photodetector

TL;DR

This study demonstrates room-temperature mid-infrared two-photon absorption in an extended-wavelength InGaAs photodetector, revealing potential for new applications in this spectral range.

Contribution

First measurement of two-photon absorption in extended-wavelength InGaAs at room temperature, confirming theoretical predictions and expanding application prospects.

Findings

Measured two-photon absorption coefficient of 0.6 cm/MW

Agreement with theoretical $E_g^{-3}$ scaling law

Potential for applications between 1.8 and 5.6 μm

Abstract

We investigate the nonlinear optical response of a commercial extended-wavelength In$_{0.81}$Ga$_{0.19}$As photodetector. Degenerate two-photon absorption in the mid-infrared range is observed at room temperature using a quantum cascade laser emitting at $\lambda=4.5~\mu$m as the excitation source. From the measured two-photon photocurrent signal we extract a two-photon absorption coefficient $\beta^{(2)} = 0.6 \pm 0.2$ cm/MW, in agreement with the theoretical value obtained from the $E_g^{-3}$ scaling law. Considering the wide spectral range covered by extended-wavelength In$_x$Ga$_{1-x}$As alloys, this result holds promise for new applications based on two-photon absorption for this family of materials at wavelengths between 1.8 and 5.6 $\mu$m.