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

Area of Science:

• Optics and Photonics
• Metamaterials
• Nanotechnology

Background:

• Traditional beam splitters (prisms, wave plates) are bulky, limiting miniaturized optical systems.
• Developing nanoscale beam splitters with flexible functionality is a key research area.
• Metasurfaces offer novel ways to control light at the nanoscale.

Purpose of the Study:

• To propose and design a polarization-insensitive beam splitter with tunable split angle and ratio.
• To demonstrate the feasibility of using phase gradient metasurfaces for beam splitting.
• To overcome the limitations of conventional beam splitters in miniaturized optical applications.

Main Methods:

• Designed a beam splitter using two types of nanorod arrays with opposite phase gradients.
• Varied the split angle by adjusting the phase gradient magnitude, following Snell's law.
• Tuned the split ratio by incorporating phase buffers of varying areas.
• Simulated and analyzed the performance of four distinct beam splitter designs.

Main Results:

• Achieved a variable split angle range of 12-29 degrees.
• Enabled a variable split ratio range from 0.1 to 1.
• Demonstrated high beam splitting efficiency (>0.3) across the 480-600 nm wavelength range.
• Exhibited weak polarization dependence.

Conclusions:

• The proposed phase gradient metasurface beam splitter is compact and easily integrated.
• Offers tunable optical functionalities crucial for advanced optical circuits.
• Suitable for applications in multiplexers, interferometers, and integrated optical circuits.