System calibration for single-wavelength multi-terabit mode-division multiplexing free-space optical communication...

Area of Science:

• Optical Communications
• Free-Space Optics
• Signal Processing

Background:

• Mode-division multiplexing (MDM) is crucial for increasing free-space optical communication capacity.
• Inter-mode crosstalk is a significant challenge in MDM systems, limiting performance.
• Accurate optical calibration is essential for reliable MDM system operation.

Purpose of the Study:

• To propose a novel optical calibration strategy for a single-wavelength MDM MIMO free-space optical communication system.
• To minimize inter-mode crosstalk and signal distortions in the system.
• To maximize the achievable information rate (AIR) of the communication system.

Main Methods:

• Utilized 6 Hermite-Gaussian modes for the MDM MIMO system.
• Employed higher-order modes at the receiver for optical setup calibration.
• Implemented Volterra pre-distortion to minimize signal distortions for 80 GBaud signals.
• Transmitted probabilistically-shaped 256-QAM signals.

Main Results:

• Achieved a record-high AIR of 4.49 Tbit/s/λ.
• Successfully minimized inter-mode crosstalk through the proposed calibration strategy.
• Demonstrated effective signal distortion mitigation using Volterra pre-distortion.

Conclusions:

• The proposed optical calibration strategy significantly enhances the performance of MDM MIMO free-space optical communication systems.
• The system demonstrates a record-breaking data rate, paving the way for future high-capacity optical wireless communication.
• Optimized signal processing techniques and mode utilization are key to overcoming limitations in free-space optical communications.