Dynamic response of metamaterials in the terahertz regime: Blueshift tunability and broadband phase modulation

Terahertz time-domain spectroscopy is used to probe the electromagnetic properties of metamaterials, which are dynamically photoexcited, using synchronized femtosecond near-infrared laser pulses. Blueshift tunability of the electric dipole metamaterial's resonance, as well as a broadband phase tunability reaching similar to pi/4, are demonstrated. Numerical simulations show the observations are due to changes in the complex index of the photoexcited semiconductor substrate.