Abstract-All-optical switchable terahertz spin-photonic devices based on vanadium dioxide integrated metasurfaces

Jie Li, Jitao Li, Yating Zhang, Jining Li, Yue Yang, Hongliang Zhao, Chenglong Zheng, Jiahui Li, Jin Huang, Fuyu Li, Tingting Tang, Jianquan Yao,



https://www.sciencedirect.com/science/article/abs/pii/S0030401819310545

Metasurfaces based on Pancharatnam-Berry (P-B) phase can achieve strong spin angular momentum (SAM) to orbital angular momentum (OAM) conversion of light, which provides a new degree of freedom for light control and opens up a new way for the applications of metasurfaces in classical and quantum optics. With the development of high-speed, large-capacity information transmission and high-definition imaging, demand for multifunctional and tunable P-B phase metasurfaces increases. Here, we propose three switchable terahertz spin-photonic devices based on P-B phase metasurfaces for focusing (divergence), splitting and vortex generation of terahertz beams. Based on photo-induced insulator–metal phase transition of the vanadium dioxide (VO2) islands in reflective hybrid resonators, switching of the devices function between on- and off-state is obtained, and the amplitude switching efficiency is as high as 90%. This work provides new ideas for the design of active terahertz devices and facilitates the applications of terahertz spin-photonic devices based on metasurfaces.

Abstract-Frequency-switchable VO-based coding metasurfaces at the terahertz band

Jiahui Li, Yating Zhang, Jining Li, Jie Li, Yue Yang, Jin Huang, Chengqi Ma, Zhenzhen Ma, Zhang Zhang, Lanju Liang, Jianquan Yao



https://www.sciencedirect.com/science/article/abs/pii/S0030401819309204

In this paper, a frequency-switchable terahertz coding metasurface is demonstrated based on the phase transition of vanadium dioxide. Temperature excitation can initiate the insulator–metal transition of vanadium dioxide, thereby changing the resonant frequency of the metal-vanadium dioxide composite unit structure, then changing the operating frequency of the entire coding metasurfaces. We first design a 1-bit coding metasurface whose working frequency can be switched between 1 THz and 1.4 THz, with a switching bandwidth of 0.4 THz. Further more, a 2-bit coding metaurface is designed, whose working frequency can be switched between 1 THz and 1.5 THz with a switching bandwidth of 0.5 THz. This work provides a new design idea for the terahertz active coding metasurfaces which opens up a broad path for coding metasurface applications such as wireless terahertz communications.