Tunable terahertz metamaterial with polarization dependent and independent characteristics

Abstract

We present four kinds of tunable terahertz (THz) metamaterials (TTMs) composed of spilt-ring resonators (SRRs) with different splits and inner movable structures. According to the numbers of splits, these four designs are based on the conventional SRR with single-, dual-, triple- and quad-split denoted as TTM-1, TTM-2, TTM-3, and TTM-4, respectively. These four TTMs exhibit polarization-dependent and polarization-independent characteristics depending on whether the SRR structures are symmetrical or asymmetrical configuration. By increasing the height of the inner movable structure, the tunability of the resonant frequency of TTMs is explored. These results show that these TTMs can achieve different tuning ranges in transverse electric (TE) and transverse magnetic (TM) modes. The resonances are stable for TTM-1 in TE and TM modes, and TTM-2 in TE mode. TTM-3 exhibits the tuning range of 0.202 THz in TE mode and 0.176 THz in TM mode, while TTM-4 exhibits the tuning range of 0.198 THz in both TE and TM modes. The maximum tuning range is 0.306 THz by implementing TTM-2 in TM mode. These designs possess anti-vibration and tunable characteristics, which provide a potential possibility for the use in the THz-wave optoelectronic devices with high tunability, flexibility, and applicability.