Non-uniform optical phased array with a large steering angle and high side mode suppression ratio.

Area of Science:

• Photonics and Optical Engineering
• Array Signal Processing

Background:

• Optical phased arrays (OPAs) are key for light detection and ranging.
• Non-uniform arrays offer grating lobe-free steering but face reduced side mode suppression ratio (SMSR) at large angles.
• Optimizing emitter spacing is crucial for maintaining OPA performance.

Purpose of the Study:

• To enhance the performance of non-uniform optical phased arrays (OPAs) at large steering angles.
• To investigate the effectiveness of multi-objective optimization algorithms for OPA design.
• To improve the side mode suppression ratio (SMSR) of OPAs without introducing grating lobes.

Main Methods:

• Utilized the non-dominated sorting genetic algorithm-II (NSGA-II), a multi-objective optimization technique.
• Designed and optimized 64-, 128-, and 256-channel non-uniform OPAs.
• Compared performance metrics against arrays optimized using a standard genetic algorithm.

Main Results:

• Optimized non-uniform OPAs demonstrated improved SMSR at an 80° steering angle.
• Specific SMSR improvements of 2.18 dB (64-channel), 2.61 dB (128-channel), and 2.56 dB (256-channel) were achieved.
• The NSGA-II algorithm effectively addressed the trade-offs in OPA design.

Conclusions:

• Multi-objective optimization using NSGA-II significantly enhances OPA performance, particularly SMSR at large angles.
• Non-uniform array designs optimized with NSGA-II provide a viable solution for high-performance light detection and ranging.
• This approach overcomes limitations of traditional OPA designs, enabling wider angle steering with improved signal quality.