480-nm distributed-feedback InGaN laser diode for 10.5-Gbit/s visible-light communication

Area of Science:

• Optoelectronics
• Semiconductor Lasers
• Visible-Light Communication

Background:

• High-performance lasers are crucial for advanced optical communication systems.
• Sky-blue emitters are needed for specific applications like underwater communication and spectroscopy.
• Existing laser diodes often lack the narrow linewidth and high stability required for demanding applications.

Purpose of the Study:

• To demonstrate a novel distributed-feedback (DFB) InGaN-based laser diode with narrow-linewidth emission at ~480 nm (sky blue).
• To investigate the application of this laser diode in high-speed visible-light communication (VLC).

Main Methods:

• Fabrication and characterization of a DFB InGaN-based laser diode.
• Continuous-wave (CW) operation measurements including side-mode suppression ratio (SMSR), optical power, and linewidth.
• Implementation of VLC links using non-return-to-zero on-off keying (NRZ-OOK) and 16-quadrature-amplitude-modulation orthogonal frequency-division multiplexing (16-QAM-OFDM) schemes.

Main Results:

• Achieved narrow-linewidth emission at ~480 nm with a resolution-limited linewidth of ~34 pm.
• Obtained a high SMSR of 42.4 dB and optical power of ~14 mW under CW operation.
• Demonstrated a 5 Gbit/s VLC link using NRZ-OOK and a high-speed 10.5 Gbit/s VLC data rate using 16-QAM-OFDM.

Conclusions:

• The developed sky-blue DFB laser diode exhibits high performance suitable for advanced VLC systems.
• This laser opens possibilities for dense wavelength-division multiplexing (DWDM) in VLC and other single-frequency laser applications.
• Potential benefits for underwater communication and spectroscopy near the H-beta Fraunhofer line (~486 nm).