Abstract-Achromatic Dielectric Metasurface with Linear Phase Gradient in the Terahertz Domain

 

Ridong Jia,   Yufei Gao,   Quan Xu,   Xi Feng,   Qingwei Wang,  Jianqiang Gu,   Zhen Tian, Chunmei Ouyang,   Jiaguang Han,   Weili Zhang

https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.202001403

The notion of metasurface has inspired the innovation of various functional devices in the terahertz band, but the intrisinc dispersion restricts their application in broadband scenarios. Here, two terahertz achromatic linear‐phase‐gradient metasurface devices are demonstrated, which are a beam deflector and a beam splitter, respectively. The phase and dispersion of the metasurfaces are simultaneously engineered by changing the geometric parameters of the unit cells made of silicon gratings and pillars. The simulated and experimental results demonstrate the achromatic feasibility of the beam deflector from 0.6 to 1.2 THz and of the beam splitter from 0.6 to 1.1 THz. The transmittances and the splitting ratios of the achromatic beam splitter are also analyzed. The metasurface based achromatic beam deflector and splitter presented here not only enrich the terahertz functional devices, but the methods and structures may also promote the research of broadband terahertz metasurfaces.

Abstract-Terahertz Spoof Surface Plasmonic Logic Gates

 

Mingrui Yuan, Qingwei Wang, Yanfeng Li, Yuehong Xu, Quan Xu, Xueqian Zhang, Xixiang Zhang, Jiaguang Han, Weili Zhang, 

https://www.sciencedirect.com/science/article/pii/S2589004220308774

Logic gates are important components in integrated photonic circuitry. Here, a series of logic gates to achieve fundamental logic operations based on linear interference in spoof surface plasmon polariton waveguides are demonstrated at terahertz frequencies. A metasurface-based plasmonic source is adopted to couple free-space terahertz radiation into surface waves, followed by a funnel-shaped metasurface to efficiently couple the surface waves to the waveguides built on a domino structure. A single Mach-Zehnder waveguide interferometer can work as logic gates for four logic functions: AND, NOT, OR, and XOR. By cascading two such interferometers, NAND and NOR operations can also be achieved. Experimental investigations are supported by numerical simulations, and good agreement is obtained. The logic gates have compact sizes and high intensity contrasts for the output “1” and “0” states. More complicated functions can be envisioned and will be of great value for future terahertz integrated computing.