2.3 Gbit/s underwater wireless optical communications using directly modulated 520 nm laser diode

Area of Science:

• Optical Engineering
• Wireless Communication
• Photonics

Background:

• Underwater wireless optical communication (UWOC) is crucial for high-bandwidth data transmission in aquatic environments.
• Existing UWOC systems face limitations in speed and distance due to factors like water turbidity and component bandwidth.
• Advancements in laser and photodetector technology are key to overcoming these challenges.

Purpose of the Study:

• To experimentally demonstrate a record high-speed underwater wireless optical communication (UWOC) system.
• To evaluate the performance of an on-off keying non-return-to-zero (OOK-NRZ) modulation scheme in an UWOC link.
• To achieve data rates exceeding previous benchmarks in UWOC.

Main Methods:

• Utilized a commercial 520 nm laser diode (LD) with 1.2 GHz bandwidth as the transmitter.
• Employed an avalanche photodiode (APD) module as the receiver for high sensitivity.
• Implemented an on-off keying non-return-to-zero (OOK-NRZ) modulation scheme for data transmission.
• Conducted experiments over a 7-meter underwater communication link.

Main Results:

• Achieved a record data rate of 2.3 Gbit/s in the UWOC system.
• Measured a bit error rate (BER) of 2.23×10⁻⁴, which is below the forward error correction (FEC) threshold of 2×10⁻³.
• Demonstrated successful error-free communication over the 7-meter distance.

Conclusions:

• The combination of a high-bandwidth laser diode, sensitive avalanche photodiode, and optimized conditions enables high-speed UWOC.
• The achieved data rate of 2.3 Gbit/s represents a significant advancement in UWOC technology.
• This study sets a new benchmark for data transmission speeds in underwater wireless optical communication.