Actively switchable terahertz metamaterial

Abstract

We present four designs of actively switchable terahertz metamaterials (ASTMs) to explore their extraordinary optical characteristics. They are denoted as ASTM_1, ASTM_2, ASTM_3, and ASTM_4, respectively. ASTM_1 and ASTM_2 are composed of asymmetrically single-layer L-shaped metamaterial and asymmetrically dual-layer L-shaped metamaterial with rotated 0° on Si substrate, respectively. ASTM_3 and ASTM_4 are composed of asymmetrically dual-layer L-shaped metamaterial with rotated 90° and asymmetrically connected L-shaped metamaterial on Si substrate, respectively. ASTM_1 shows three resonances at 0.19 THz, 0.33 THz, and 0.49 THz. The tuning range of first resonance is 0.06 THz by changing the gap between the L-shaped metamaterial. While ASTM_2 shows three resonances at 0.15 THz, 0.28 THz, and 0.42 THz. The tuning range of first resonance is 0.05 THz by changing the height between top and bottom L-shaped metamaterials. By changing the gap and height of L-shaped metamaterials, ASTM_3 and ASTM_4 exhibit the optical switching characteristic. The transmission spectra of four ASTMs show the polarization-independent characteristic. Such optical properties of ASTM designs provide the possibilities of THz metamaterial to be used in active switching optoelectronics applications, such as sensors, logic devices, programmable devices, and so on. Keywords: Metamaterial, Terahertz, Modulator, Resonator, Switch