Optical Control of Metamaterial Unit Cells at Microwave Frequencies

We have developed metamaterial unit cells whose properties can be controlled dynamically using near-infrared light. The structures consist of split ring resonators (SRRs) operating at microwave frequencies that contain a piece of low-doped silicon in their gap. We show that the SRR response strongly depends on the silicon resistivity and exploit this property to modulate the amplitude or tune the frequency of the SRR resonance by photodoping the semiconductor with an 815 nm laser diode. We present several designs and experimental demonstrations of elementary active photonic devices based on this approach.