  Recent work on mid-infrared (MIR) detection through the process of
non-degenerate two-photon absorption (NTA) in semiconducting materials has
shown that wide-field MIR imaging can be achieved with standard Si cameras.
While this approach enables MIR imaging at high pixel densities, the low
nonlinear absorption coefficient of Si prevents fast NTA-based imaging at lower
illumination doses. Here we overcome this limitation by using InGaAs as the
photosensor. Taking advantage of the much higher nonlinear absorption
coefficient of this direct bandgap semiconductor, we demonstrate high-speed MIR
imaging up to 500 fps with under 1 ms exposure per frame, enabling 2D or 3D
mapping without pre- or post-processing of the image.
