Transient optical modulation properties in the terahertz metamaterial of split ring resonators

The ultrafast optical modulation properties of split ring resonators are characterized by utilizing optical pump--terahertz probe spectroscopy. The experimental results show that when the terahertz electric vector is perpendicular to the gap of the split ring resonator, resonant absorption can be quenched significantly under high pump excitation. However, when the terahertz electric vector is parallel to the gap, the resonant absorption is less sensitive to pump excitation due to the structural properties of the metamaterial. Our numerical simulations also demonstrate that the pump pulse significantly influences the split ring resonator current by generating carriers in the substrate.