Abstract-A Tunable Polarization-Dependent Terahertz Metamaterial Absorber Based on Liquid Crystal

Guangsheng Deng, Yujiao Lu, Zhiping Yin,  Weien Lai, Hongbo Lu,  Jun Yang, Aifeng Yang, Yang Ye, Dayong Liu, Baihong Chi,

http://www.mdpi.com/2079-9292/7/3/27

In this paper, a tunable polarization-dependent terahertz (THz) metamaterial absorber based on liquid crystal (LC) is presented. The measurement results show that absorption peak is at 239.5 GHz for a TE-polarized wave and 306.6 GHz for a TM-polarized wave, without exerting the bias voltage on the LC layer. An increase in bias voltage affects the orientation of LC molecules and causes redshifted resonant frequencies. By adjusting the bias voltage from 0 to 10 V, frequency tunabilities of 4.7% and 4.1% for TE- and TM-polarized waves, respectively, were experimentally demonstrated. Surface current and power loss distribution was analyzed to explain the physical mechanism of the absorber, while the absorption dependence on geometrical parameters and incident angles was also studied in detail. According to the obtained results, the proposed absorber is shown here to be capable of achieving tunable polarization-dependent absorption, and to have potential application in terahertz polarization imaging, terahertz sensing, and polarization multiplexing

Abstract-Electrically tunable terahertz dual-band metamaterial absorber based on a liquid crystal

Zhiping Yin,  Yujiao Lu,  Tianyu Xia,  Weien Lai,  Jun Yang,  Hongbo Lua,  Guangsheng Deng,

http://pubs.rsc.org/en/content/articlelanding/2018/ra/c7ra13047c#!divAbstract

In this paper, a liquid crystal (LC) based tunable metamaterial absorber with dual-band absorption is presented. The proposed absorber is analysed both numerically and experimentally. The analysis shows that the two absorption peaks, originating from the new resonant structure, are experimentally detected at 269.8 GHz and 301.4 GHz when no bias voltage is applied to the LC layer. In order to understand the absorption mechanisms, simulation results for the surface current and power loss distributions are presented. Since liquid crystals are used as the dielectric layer to realize the electrically tunable absorber, a frequency tunability of 2.45% and 3.65% for the two absorption peaks is experimentally demonstrated by changing the bias voltage of the LC layer from 0 V to 12 V. Furthermore, the absorber is polarization independent and a high absorption for a wide range of oblique incidence is achieved. The designed absorber provides a way forward for the realization of tunable metamaterial devices that can be applied in multi-band detection and imaging.