Net 4 Gb/s underwater optical wireless communication system over 2 m using a single-pixel GaN-based blue mini-LED and...

Area of Science:

• Optoelectronics
• Optical Communications
• Materials Science

Background:

• Gallium Nitride (GaN)-based mini-light-emitting diodes (LEDs) are suitable for underwater optical wireless communication (UOWC) due to established fabrication processes.
• Mini-LEDs are crucial components for high-speed UOWC systems.

Purpose of the Study:

• To fabricate and characterize GaN-based mini-LEDs for high-speed UOWC applications.
• To investigate the impact of mini-LED diameter on modulation bandwidth and optical modulation amplitude.

Main Methods:

• Fabrication of mini-LEDs with varying mesa diameters (100 µm to 175 µm) using a single-layer Indium Gallium Nitride (InGaN) active region.
• Characterization of mini-LEDs, including measurement of 3-dB optical bandwidth.
• Demonstration of a UOWC link using the optimized mini-LED and Pulse Amplitude Modulation with 4 levels (PAM-4) signaling.

Main Results:

• The mini-LED with a 150 µm diameter exhibited the best performance, achieving a 3-dB optical bandwidth of 906 MHz.
• A net data rate of 4 Gb/s was successfully transmitted over 2 meters of underwater distance.
• The system utilized only linear equalization, demonstrating efficient signal processing.

Conclusions:

• Optimized GaN-based mini-LEDs are highly effective for high-speed UOWC.
• The demonstrated UOWC system achieved the highest net data rate and data-rate-distance product for a single-pixel mini-LED.
• This technology holds significant potential for advancing underwater communication capabilities.