Direct observation of electro-optic modulation in a single split-ring resonator

We study experimentally and numerically the electro-optic (EO) effect in a single metamaterial cell incorporating a nonlinear crystal. A metal split-ring fabricated on a ZnTe substrate resonating at 3 GHz was excited with a tunable microwave source. A linearly polarized laser beam probed the EO effect. Enhanced EO modulation was observed in the split-gap at the resonant frequency proportional to Q-factor. The electric field surrounding the metamaterial element in the ZnTe was mapped by the EO effect and agrees well with simulation. We show that high-Q metamaterials incorporating an EO crystal in the split-gap could lead to improved EO devices.