Subwavelength imaging using phase-conjugating nonlinear nanoantenna arrays.

We investigate the use of nonlinear metasurfaces formed by plasmonic nanoantennas loaded with χ(3) nonlinear elements, in order to realize subwavelength imaging based on phase conjugation and time reversal. The nanoantennas' plasmonic resonance is used to boost the nonlinear response over an ultrathin surface, meeting the conditions for efficient phase conjugation necessary for imaging applications. Pairing two such surfaces, we put forward a realistic design for a time-reversal 'perfect lens', which can overcome the limitations in resolution and sensitivity to losses typical of negative-index lenses.