Ultrahigh-speed violet laser diode based free-space optical communication beyond 25 Gbit/s

Area of Science:

• Optical Communications
• Wireless Technology
• Laser Systems

Background:

• Free-space optical (FSO) communication offers high bandwidth potential for wireless data transmission.
• Violet laser diodes (VLDs) present an opportunity for novel FSO system development.
• Achieving ultrahigh data rates in FSO links requires advanced modulation and robust system design.

Purpose of the Study:

• To demonstrate an ultrahigh-speed point-to-point free-space optical system utilizing a violet laser diode (VLD).
• To investigate the performance of a VLD-based FSO link using 64-quadrature amplitude modulation discrete multi-tone (64-QAM DMT) data streams.
• To evaluate the system's data rate, signal quality, and performance over varying transmission distances.

Main Methods:

• Directly encoding a VLD with a 64-QAM DMT data stream for optical wireless communication.
• Transmitting data through free space over distances ranging from 0.5 to 10 meters.
• Receiving the optical signal with a high-speed p-i-n photodiode and analyzing performance metrics.

Main Results:

• An ultrahigh bit rate of up to 26.4 Gbps was achieved using the VLD-based FSO link.
• The system demonstrated a clear constellation plot with an error vector magnitude (EVM) of 8.57% and a signal-to-noise ratio (SNR) of 21.34 dB.
• Performance metrics showed slight degradation with increased distance, with data rates decreasing from 25.8 to 24 Gbps as distance extended from 3 to 10 meters.

Conclusions:

• The VLD-based FSO system is a viable technology for ultrahigh-speed point-to-point wireless data transmission.
• The system achieves high data rates and acceptable signal quality within a moderate free-space range.
• Further research can explore optimizing modulation schemes and mitigating performance degradation for extended FSO links.