Abstract:

We investigate the nonlinear optical response of a commercial extended-wavelength In0.81Ga0.19As uncooled photodetector. Degenerate two-photon absorption in the mid-infrared range is observed using a quantum cascade laser emitting at lambda = 4.5 lm as the excitation source. From the measured twophoton photocurrent signal, we extract a two-photon absorption coefficient beta((2)) = 0.660.2 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 InxGa1-xAs alloys, this result holds promise for applications based on two-photon absorption for this family of materials at wavelengths between 1.8 and 5.6 mu m. Published by AIP Publishing.