  Infrared imaging is a crucial technique in a multitude of applications,
including night vision, autonomous vehicles navigation, optical tomography, and
food quality control. Conventional infrared imaging technologies, however,
require the use of materials like narrow-band gap semiconductors which are
sensitive to thermal noise and often require cryogenic cooling. Here, we
demonstrate a compact all-optical alternative to perform infrared imaging in a
metasurface composed of GaAs semiconductor nanoantennas, using a nonlinear
wave-mixing process. We experimentally show the up-conversion of short-wave
infrared wavelengths via the coherent parametric process of sum-frequency
generation. In this process, an infrared image of a target is mixed inside the
metasurface with a strong pump beam, translating the image from infrared to the
visible in a nanoscale ultra-thin imaging device. Our results open up new
opportunities for the development of compact infrared imaging devices with
applications in infrared vision and life sciences.
