He Quan, Shen Zhe
School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Nanomaterials (Basel). 2021 Dec 30;12(1):113. doi: 10.3390/nano12010113.
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.
分束器是光学系统中一种常见且关键的元件。由棱镜或波片组成的传统分束器由于体积大、重量重，难以应用于小型化光学系统。具有灵活功能的纳米级分束器的实现引起了研究人员的广泛关注。在此，我们基于相位梯度超表面提出了一种具有可变分束角和分束比的偏振不敏感分束器，它由两种具有相反相位梯度的纳米棒阵列组成。根据折射定律原理，通过改变相位梯度的大小实现不同的分束角，通过添加不同面积的相位缓冲器实现不同的分束比。在设计的四种不同功能的分束器中，分束角在12 - 29°范围内可变，分束比在0.1 - 1范围内可变。该分束器在480 - 600 nm波长处具有高于0.3的高分束效率和较弱的偏振依赖性。所提出的分束器具有尺寸小、易于集成的优点，可应用于各种光学系统，如集成光路的复用器和干涉仪。
