Aliasing suppression of GaN-based homogeneous circular polarizer monolithically compatible with surface-emitting lasers

Area of Science:

• Metasurface optics
• Nanophotonics
• Semiconductor device fabrication

Background:

• Circular polarizers are crucial optical components.
• Existing designs often suffer from polarization sensitivity and integration challenges.

Purpose of the Study:

• To design and fabricate a polarization-insensitive homogeneous circular polarizer (HCP) metasurface.
• To demonstrate its capability for converting linear polarization to circular polarization with high efficiency and specific deflection characteristics.

Main Methods:

• Design of a single-layer homogeneous circular polarizer (HCP) metasurface using GaN epitaxy.
• Fabrication of the metasurface.
• Experimental characterization of its optical performance, including polarization conversion and efficiency.
• Suppression of aliasing effects by optimizing the phase gradient.

Main Results:

• The metasurface exhibits polarization-insensitive operation, converting incident linear polarization to specific circular polarization states.
• A high degree of circular polarization was achieved (0.95 simulated, 0.88 experimental).
• Average power efficiency reached 50% in simulation and 40% in experiments, with a 75° deflection angle for one circular polarization component.

Conclusions:

• The developed GaN-based HCP metasurface offers efficient and polarization-insensitive circular polarization conversion.
• Its unique deflection properties and insensitivity to incident polarization make it suitable for monolithic integration with lasers.
• This technology advances the development of compact and high-performance optical components for photonic integrated circuits.