Highly robust underwater wireless optical communication system with optical background rejection and adaptive...

Area of Science:

• Underwater wireless optical communication (UWOC)
• Optical engineering
• Signal processing

Background:

• Concurrent operation of UWOC and artificial illumination is essential for underwater platforms.
• Intense background illumination degrades UWOC performance, reducing SNR and increasing BER.
• Existing systems struggle with reliable data transmission in high-illumination scenarios.

Purpose of the Study:

• To develop a highly robust UWOC system with significant tolerance to background illumination.
• To enable reliable underwater data links in strong illumination environments.
• To demonstrate successful UWOC performance under challenging conditions.

Main Methods:

• Synergistic optical-electrical architecture combining spectral avoidance and 5-ns gated sampling.
• Real-time FPGA-implemented sliding-window adaptive decision threshold (ADTSW) algorithm.
• System-level equivalent tolerance exceeding 30 dB to background illumination.

Main Results:

• Achieved a 33 m UWOC link at 20 Mbps in pool water under 300 W illumination.
• Demonstrated uninterrupted HD video streaming over a 17 m link at 3.125 Mbps in the South China Sea.
• Exhibited over 20 dB optical rejection and over 10 dB electrical-domain suppression.

Conclusions:

• The proposed UWOC system provides a reliable solution for underwater data transmission in strong illumination.
• The synergistic optical-electrical approach effectively mitigates background light interference.
• Successful field tests confirm the system's viability for diverse underwater applications.