Inverse-Designed Ultra-Compact Passive Phase Shifters for High-Performance Beam Steering

Area of Science:

• Photonics and Optical Engineering
• Nanotechnology
• Computational Electromagnetics

Background:

• Traditional optical phased arrays often require complex fabrication and large footprints.
• Achieving wide-angle beam steering with compact devices remains a significant challenge in optical systems.
• Passive phase shifters are crucial components for controlling light direction in optical phased arrays.

Purpose of the Study:

• To design and demonstrate ultra-compact passive phase shifters for optical phased array applications.
• To investigate the wavelength-dependent phase shifting characteristics of engineered waveguides.
• To integrate these phase shifters with grating emitters for beam-steering functionalities.

Main Methods:

• Utilized multi-objective particle swarm optimization for inverse design of phase shifters.
• Employed rectangular waveguides with random air-hole arrays to induce wavelength-dependent phase differences.
• Fabricated and characterized the performance of integrated beam-steering structures.

Main Results:

• Achieved significant phase tuning ranges of 6.26 rad (TE) and 6.95 rad (TM) over a 30 nm bandwidth (1535-1565 nm).
• Demonstrated phase shifters with higher transmission and a much smaller footprint compared to array waveguide gratings.
• Integrated structures exhibited large lateral scanning ranges of ±25.47° (TE) and ±27.85° (TM).

Conclusions:

• The developed inverse-designed passive phase shifters offer a promising solution for ultra-compact optical systems.
• This technology facilitates the development of high-performance optical phased array LiDARs with wide scanning capabilities.
• The approach provides a pathway towards miniaturized and efficient beam-steering devices for various photonic applications.