Ultrafast reset-free integrated polarization tracking enabled by thin-film lithium tantalate

Area of Science:

• Photonics and Optical Communications
• Integrated Photonics
• Artificial Intelligence Hardware

Background:

• High-bandwidth and energy-efficient data-center interconnects are crucial for AI computing.
• Self-homodyne coherent (SHC) transmission simplifies digital signal processing but is hindered by ultrafast polarization fluctuations.
• Existing polarization control methods struggle with the speed and stability required for next-generation optical networks.

Purpose of the Study:

• To develop an ultrafast adaptive polarization controller (APC) for stable coherent optical communications.
• To address the limitations of current polarization control in high-speed data transmission.
• To enable reliable operation of SHC systems despite rapid state-of-polarization (SOP) changes.

Main Methods:

• Co-design of a thin-film lithium tantalate photonic chip with a novel finite-boundary gradient-descent (FBGD) algorithm.
• Implementation of a low-latency real-time control system for continuous SOP tracking.
• Validation using standalone polarization-tracking and a dual-polarization 16-QAM SHC 400-Gbps transmission system.

Main Results:

• Demonstration of an ultrafast APC capable of reset-free continuous SOP tracking.
• Stable operation under continuous polarization disturbances up to 1 Mrad·s⁻¹.
• Successful validation in a 400-Gbps SHC transmission system, showcasing practical applicability.

Conclusions:

• The developed APC establishes a new operating regime for integrated polarization control.
• This technology offers a practical solution for ultrafast and reset-free polarization control in optical interconnects.
• Enables advancements in polarization-sensitive photonic systems and high-performance computing infrastructure.