  Abbe's resolution limit, one of the best-known physical limitations, poses a
great challenge for any wave systems in imaging, wave transport, and dynamics.
Originally formulated in linear optics, this Abbe's limit can be broken using
nonlinear optical interactions. Here we extend the Abbe theory into a nonlinear
regime and experimentally demonstrate a far-field, label-free, and scan-free
super-resolution imaging technique based on nonlinear four-wave mixing to
retrieve near-field scattered evanescent waves, achieving sub-wavelength
resolution of $\lambda/15.6$. This method paves the way for application in
biomedical imaging, semiconductor metrology, and photolithography.

Optics