  Subwavelength dielectric resonators assembled into metasurfaces have become a
versatile tool for miniaturising optical components approaching the nanoscale.
An important class of metasurface functionalities is associated with asymmetry
in both generation and transmission of light with respect to reversals of the
positions of emitters and receivers. Nonlinear light-matter interaction in
metasurfaces offers a promising pathway towards miniaturisation of the
asymmetric control of light. Here we demonstrate asymmetric parametric
generation of light in nonlinear metasurfaces. We assemble dissimilar nonlinear
dielectric resonators into translucent metasurfaces that produce images in the
visible spectral range being illuminated by infrared radiation. By design, the
metasurfaces produce different and completely independent images for the
reversed direction of illumination, that is when the positions of the infrared
emitter and the visible light receiver are exchanged. Nonlinearity-enabled
asymmetric control of light by subwavelength resonators paves the way towards
novel nanophotonic components via dense integration of large quantities of
nonlinear resonators into compact metasurface designs.
