Polarization-Insensitive Beam Splitter with Variable Split Angles and Ratios Based on Phase Gradient Metasurfaces

Abstract

The beam splitter is a common and critical element in optical systems. Traditional beam splitters composed of prisms or wave plates are difficult to be applied to miniaturized optical systems because they are bulky and heavy. The realization of the nanoscale beam splitter with a flexible function has attracted much attention from researchers. Here, we proposed a polarization-insensitive beam splitter with a variable split angle and ratio based on the phase gradient metasurface, which is composed of two types of nanorod arrays with opposite phase gradients. Different split angles are achieved by changing the magnitude of the phase gradient based on the principle of Snell’s law of refraction, and different split ratios are achieved by adding a phase buffer with different areas. In the designed four types of beam splitters for different functions, the split angle is variable in the range of 12–29°, and the split ratio is variable in the range of 0.1–1. The beam splitter has a high beam splitting efficiency above 0.3 at the wavelength of 480–600 nm and a weak polarization dependence. The proposed beam splitter has the advantages of a small size and easy integration, and it can be applied to various optical systems such as multiplexers and interferometers for integrated optical circuits.

Optically Controlled Terahertz Dynamic Beam Splitter with Adjustable Split Ratio

“…These results indicate the outstanding performance of our beam splitter in terms of the adjustable split ratio and stable split angles. Compared with previous work [ 29 , 30 ] in which the split ratio or angle were changed by designing different structures, our beam splitter has the advantage of having an active metasurface that can realize multifunctionalization with one sample. This is beneficial for the development of integrated devices in terahertz systems.…”

Quasi-Freeform Metasurfaces for Wide-Angle Beam Deflecting and Splitting

“…Specifically, we compared the splitting efficiency and splitting angle in each work. Previously reported beam splitters were forwardly designed based on gradient metasurfaces [ 15 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ], which can be implemented easily, although at the cost of low efficiency and small angle. Among these works, a highest splitting efficiency and maximum splitting angle were achieved by Liu et al [ 34 ], where the splitting efficiency and angle were 93.4% and 50°, respectively.…”

“…Hence, a design strategy that can realize high deflecting performance with less-consuming time is needed. As for the metasurface-based beam splitters, recent works were mainly conducted by utilizing forward design method to improve the splitting performance of gradient metasurfaces [ 15 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Among these beam splitters, a splitting efficiency of 93.4% was achieved, while the splitting angle was only 50° [ 34 ].…”

Conical holes arrays for 2 × 2 ports division

“…Various methods and structures, including photonic crystals [13][14][15], wave plates [16,17], and metasurface [3,[18][19][20][21], are used to implement beam splitters. However, conventional optical components used to create beam splitters, are bulky and heavy, which leads to problems in integrating them into miniature optical circuits [22]. Therefore, beam splitters designed with a two-dimensional (2D) metal grating based on metasurface provide a solution to these problems.…”