Random-phase metasurface-assisted optical phased arrays for large-FoV and high-resolution beam steering

Area of Science:

• Photonics and Metamaterials
• Optical Engineering
• Beam Steering Technology

Background:

• Optical phased arrays (OPAs) are crucial for applications like LiDAR and optical communication.
• Existing OPAs face limitations such as restricted field of view (FoV) due to grating lobes and complex array designs.
• Challenges include the need for high-precision, tunable lasers in one-dimensional (1D) OPAs.

Purpose of the Study:

• To introduce a novel method for enhancing OPA beam-steering performance.
• To overcome limitations of current OPAs, specifically grating lobes and restricted FoV.
• To provide a practical, scalable, and cost-effective solution for advanced OPA systems.

Main Methods:

• Development of a theoretical model to explain the working principle of a passive random-phase metasurface for OPA field reconstruction.
• Analysis of beam-steering performance metrics, including side lobe suppression ratio (SLSR), resolution, and efficiency, in relation to system parameters.
• Numerical simulations to validate the theoretical model and demonstrate 2D beam steering using a 1D OPA combined with a random-phase metasurface, leveraging the optical memory effect.

Main Results:

• The proposed method effectively suppresses grating lobes and broadens the element radiation pattern, leading to improved resolution.
• Quantitative relationships between performance metrics (SLSR, resolution, efficiency) and system parameters (number of channels, propagation distance) were established.
• Numerical demonstration of 2D beam steering without lenses or wavelength tuning, enabled by continuous steering via the optical memory effect.

Conclusions:

• A passive random-phase metasurface offers a practical, low-cost, and scalable approach to significantly enhance OPA beam-steering capabilities.
• The study provides valuable design guidelines for integrating OPAs with metasurfaces for advanced applications.
• This method addresses key limitations of current OPAs, paving the way for improved performance in diverse optical systems.