Improved SPGD algorithm for optical phased array chip phase error correction in Lidar applications.

Area of Science:

• Photonics
• Optical Engineering
• Lidar Technology

Background:

• Random phase errors in silicon-photonic optical phased array (OPA) chips degrade output beam quality.
• Efficient phase error correction is crucial for OPA-based Lidar systems.

Purpose of the Study:

• To introduce and evaluate an improved Adaptive Stochastic Parallel Gradient Descent (ASPGD) algorithm for OPA random phase error correction.
• To demonstrate the algorithm's effectiveness, particularly for large channel count OPA designs.

Main Methods:

• Development and implementation of an enhanced ASPGD algorithm.
• Experimental validation using a fabricated 16-channel silicon-photonic OPA chip.
• Comparative analysis against traditional Stochastic Parallel Gradient Descent (SPGD) and genetic algorithms.

Main Results:

• Successful demonstration of ASPGD for OPA phase error calibration on a 16-channel chip.
• ASPGD exhibited significantly faster convergence compared to SPGD and genetic algorithms.
• Higher cosine similarity values for the corrected beam profile were achieved with ASPGD, especially for increased channel counts.

Conclusions:

• The improved ASPGD algorithm provides efficient and accurate phase error correction for OPA chips.
• This algorithm shows superior performance over traditional methods for large channel count OPA designs.
• The work contributes to the practical deployment of OPA technology in chip-scale, long-range Lidar applications.