Surface plasmon-polariton resonances and optical rectification in finite gratings

The optical rectification effect is observed in periodically structured metal films (metasurfaces) with broken inversion symmetry. It is found that the finite width of the metasurface and the proximity of its edges also provide a symmetry-breaking mechanism, adding to the rectification current, which is further enhanced at surface plasmon polariton resonances. By position-and angle-resolved measurements we show that this mechanism is more efficient than the symmetry breaking achieved either by the oblique incidence of the laser light or by a nonsymmetric structure of the unit cell. The existing theory of the optical rectification can partially account for the observed phenomena.