Ultra-broadband terahertz modulation by active hybrid metamaterials

We demonstrate an ultra-broadband all-optical terahertz modulator based on a semiconductor-integrated hybrid metamaterial. Under photoexcitation using near-infrared laser pulses, the semiconductor regions become highly conducting, causing a transition of the metamaterial from an array of dipole patch grid to a metal wire grating. This transition exhibits dramatically different transmission properties and enables a broadband modulation of terahertz waves. The concept may be further extended to electrically switchable terahertz metamaterials.