Design of a metalens for beam collimation and angular amplification in optical phased array devices

Area of Science:

• Optics and Photonics
• Metamaterials
• Optical Engineering

Background:

• Optical phased arrays (OPAs) are crucial for beam steering but often face limitations in beam quality and field of view (FOV).
• Enhancing collimation (beam sharpness) and expanding FOV are key challenges for OPA device performance.
• Metasurfaces and metalenses offer tunable optical properties for advanced optical system design.

Purpose of the Study:

• To develop an analytical design for improving beam collimation and FOV in optical phased array (OPA) devices.
• To investigate the use of cylindrical and angular amplifier metalenses for enhanced OPA performance.
• To demonstrate the potential of metasurfaces for compact, integrated OPA systems.

Main Methods:

• Utilized a cylindrical metalens for beam collimation and a set of metalenses with concave/convex profiles to increase FOV.
• Applied the generalized vector law of reflection/refraction to determine ray trajectories based on metasurface phase profiles.
• Employed ray tracing simulations to analyze beam characteristics and FOV expansion.

Main Results:

• Achieved collimation of an elliptical OPA beam (21 mm vertical width) to a sharp spherical beam (1.5 mm width) using a cylindrical metalens.
• Demonstrated a nearly threefold increase in FOV for a 64-channel OPA device, expanding from 15° to 41.96°, by incorporating angular amplifier metalenses.
• Quantified the beam quality enhancement and FOV expansion through detailed ray tracing analysis.

Conclusions:

• Metasurfaces and metalenses offer a viable solution for enhancing OPA beam quality (collimation) and expanding the field of view (FOV).
• The proposed design provides significant advantages for developing compact, on-chip integrated OPA devices.
• This advancement holds promise for improving solid-state LiDAR systems and other optical applications requiring high-performance beam control.