All-optical modulation and switching by a metamaterial of plasmonic circuits.

We demonstrate experimentally the modulation and switching of one light beam by a second beam using metamaterials constructed from arrays of plasmonic circuits. Each circuit consists of three gold nanorods that mix together two coherent but orthogonally polarized light beams leading to modulation by an interference effect. By adjusting the phase and the amplitude of one of the beams, the amplitude and spectral composition of the second beam is altered. The plasmonic circuits display an asymmetry that enables an angle-dependent modulation, which we demonstrate with a diffraction grating where the energy directed into two diffraction orders is controlled by a second light beam. This effect appears like an optically controlled blaze that we use to switch a light beam between two different directions.