Actively tunable terahertz chain-link metamaterial with bidirectional polarization-dependent characteristic

Liu, Pengyu, Zihao Liang, Zhicheng Lin, Zefeng Xu, Ruijia Xu, Dongyuan Yao, and Yu-Sheng Lin. "Actively tunable terahertz chain-link metamaterial with bidirectional polarization-dependent characteristic." Scientific reports 9, no. 1 (2019): 1-8.

Abstract

A tunable terahertz (THz) chain-link metamaterial (CLM) is presented, which is composed of a tailored Au layer fabricated on Si substrate. CLM exhibits bidirectional polarization-dependent characteristic by applying a direct-current (dc) bias voltage on device. This CLM device can be heated up the surrounding temperature to tune the corresponding resonance. The tuning range is 0.027 THz from 0.318 THz to 0.291 THz on the bias of 0.60 V to 1.32 V. By reconfiguring the gap between CLM, there are single-resonance with red-shift at TE mode, and multi-resonance with blue-shift and red-shift at TM mode, respectively. These characterizations of CLM are polarization-dependence and bidirectional tunability. These results show the electromagnetic responses of proposed CLM device is suitable for the uses for resonator, filter, switch, and sensor in the THz frequency range.

for full paper see https://www.nature.com/articles/s41598-019-46436-w

Characterization

With the tunable CLM device, we experimentally explore the electrothermal and electrostatic effects to resonant frequency of CLM device. By increasing the dc bias voltage, the corresponding resonant frequency could be tuned. Our sample was mounted on a home-made printed-circuit board (PCB) with a transparent window. There are two conductive wires soldering on PCB and connected to a dc power supply. The sample on the PCB was placed in the chamber of THz measurement system under a nitrogen environment to eliminate water vapor. The THz transmission spectra characterization was measured using TeraView 3000 time-domain spectroscopy (THz-TDS) system. The transmission spectra were normalized with respect to transmission of pure Si substrate of the same thickness as the sample.