Characteristics of GaN-Based Micro-Light-Emitting Diodes for Mbps Medium-Long Distance Underwater Visible Light...

Area of Science:

• Optoelectronics
• Underwater Communication

Background:

• Visible light-based underwater optical wireless communication (UWOC) is crucial for long-distance, high-speed applications.
• Micro-light-emitting-diodes (micro-LEDs) offer potential for high-bandwidth UWOC systems.

Purpose of the Study:

• To propose and evaluate a high-bandwidth UWOC system using micro-LEDs with Non-Return-to-Zero On-Off Keying (NRZ-OOK) modulation.
• To investigate the impact of micro-LED structural parameter optimization on optoelectronic performance.

Main Methods:

• Numerical simulations were performed to optimize gallium nitride (GaN)-based micro-LEDs.
• Experimental validation was conducted to assess data rates and communication capabilities at various underwater distances.
• Channel characterization and parametric analysis were used to understand signal degradation.

Main Results:

• Optimizing micro-LED structural parameters enhanced modulation bandwidth and luminous efficiency.
• Maximum real-time data rates of 420 Mbps, 290 Mbps, and 250 Mbps were achieved at 2.3 m, 6.9 m, and 11.5 m, respectively.
• Successful underwater audio communication was demonstrated at 11.5 m with low optical power (12.5 µW).
• A micro-LED-specific attenuation coefficient of 0.56 dB/m was determined.
• Wavelength-dependent degradation was observed, with higher attenuation and bit error rate (BER) at longer wavelengths.

Conclusions:

• Optimized micro-LEDs significantly improve UWOC system performance for underwater applications.
• The proposed system demonstrates feasibility for high-speed data transmission and audio communication in underwater environments.
• Findings provide insights for developing advanced underwater optical systems for environmental monitoring and secure military communications.