Polarization-insensitive beam splitters with variable split ratios based on phase gradient metasurfaces.

We propose a polarization-insensitive beam splitter based on metasurface consist of cylinders with two types of phase gradients in the opposite directions. By changing the phase gradient, we found the incident light split into different directions. We set a phase buffer area to get different ratios of energy in the splitting direction to achieve adjustable splitting ratios from 0.2 to 1. This kind of beam splitter can be used in various optical systems such as multiplexers, interferometers for integrated optical circuits.