An Ultra-Thin Beam Splitter Design Using a-Si:H Based on Phase Gradient Metasurfaces

This paper explicates the design of an ultra-thin beam splitter based on phase gradient metasurfaces using amorphous silicon hydrogenated (a-Si:H) nano cylinders for the visible frequency of 474 THz. The a-Si:H nano cylinders exhibit low losses in the visible regime compared to standard a-Si, and small size due to reduced aspect ratio compared to other highly efficient materials such as TiO2 and GaN. In the proposed design, incident wave at a single operating frequency of 474 THz in visible regime is split into two different directions according to the generalized Snell's law of refraction. The angles of refracted waves are controlled by choosing different phase gradients. Based on this concept, three metasurfaces are designed and simulated using finite difference time domain numerical method for various split angles (31.8 degrees, -31.8 degrees), (-44.6 degrees, 31.8 degrees) and (-44.6 degrees, 20.5 degrees).