Nonlinear symmetry breaking in photometamaterials

We design and analyze theoretically photometamaterials with each meta-atom containing both photodiode and light-emitting diode. Illumination of the photodiode by the light-emitting diode gives rise to an additional optical feedback within each unit cell, which strongly affects resonant properties and nonlinear response of the meta-atom. In particular, we demonstrate that inversion symmetry breaking occurs upon a certain threshold magnitude of the incidentwave intensity resulting in an abrupt emergence of second-harmonic generation, whichwas not originally available, as well as in the reduced third-harmonic signal.