双频太赫兹圆极化吸波与异常反射手性超表面

Based on the theory of Jones matrix and the principle of Pancharatnam-Berry phase, a dual-band terahertz circularly-polarized (CP) absorbing and anomalous reflecting chiral metasurface is proposed in this paper. The CP chiral absorption and conversion function with anomalous reflection angles are realized independently in the two frequency bands. The metasurface unit consists of a combination of two chiral structures, which has an absorption rate of 96.3% for the incident left-hand circularly polarized (LHCP) waves, and realizes co-polarized reflection for the incident right-handed circularly polarized (RHCP) waves at a low frequency of 2.53 THz; meanwhile, the co-polarized reflection will be achieved for the LHCP waves at a high frequency of 3.43 THz, and the absorption rate of the RHCP waves is 90.9%. According to the principle of Pancharatnam-Berry phase, the full coverage of the 360° reflection phase can be realized by rotating the chiral metasurface unit. This chiral metasurface array can absorb the incident CP waves with specific handedness at two operating frequencies (low frequency 2.53 THz and high frequency 3.43 THz), and generate the handedness-preserving anomalous reflections with −26° and +19° angles for the corresponding orthogonal CP waves, respectively. This terahertz multi-function beam control device based on the chiral metasurface has numerous potential in electromagnetic energy harvesting, polarization converters, chiral sensing, radar and other fields.