Subwavelength dielectric resonators assembled into metasurfaces have become versatile tools to miniaturise optical components towards the nanoscale. An important class of such functionalities is associated with asymmetries in both generation and propagation of light with respect to reversals of the positions of transmitters and receivers. A promising pathway towards miniaturisation of asymmetric light control is via nonlinear light-matter interactions. Here we demonstrate asymmetric parametric generation of light at the level of individual subwavelength resonators. We assemble thousands of dissimilar nonlinear dielectric resonators into translucent metasurfaces that produce images in the visible spectral range when illuminated by infrared radiation. By design, these nonlinear metasurfaces produce different and completely independent images for the reversed directions of illumination, that is when the positions of the infrared transmitter and the visible light receiver are exchanged. Nonlinearity-enabled asymmetric control of light at the level of individual subwavelength resonators opens an untapped potential for developing novel nanophotonic components via dense integration of large quantities of nonlinear resonators into compact metasurfaces.
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