Wide field-of-view optical broadcasting for bi-directional indoor optical wireless communications employing PAM-4...

Area of Science:

• Optical Wireless Communications
• Indoor Networking
• Free-space Optics

Background:

• Passive optical networks (PON) are crucial for fiber-to-the-home/building deployments.
• Indoor optical wireless communication (OWC) offers high bandwidth potential but often faces limitations in coverage and mobility.
• Integrating OWC with existing fiber infrastructure can enhance network flexibility and user experience.

Purpose of the Study:

• To develop and demonstrate a wide field-of-view (FOV) bi-directional point-to-multipoint indoor OWC system.
• To enable seamless integration of OWC with passive optical networks.
• To achieve high-speed data transmission for mobile users within indoor environments.

Main Methods:

• A base station utilizing a phase-only spatial light modulator (SLM) for beam steering was employed.
• The SLM generated a composite phase mask for simultaneous downstream broadcasting and upstream signal steering.
• Nomadic user terminals employed mirror-based beam steering to achieve a wide FOV.

Main Results:

• The system achieved a wide field-of-view (FOV) for both the base station (±30°) and user terminals (±50°).
• Bi-directional data transmission was successfully demonstrated over a 4-meter range.
• A data rate of 25 Gbit/s using Pulse Amplitude Modulation with 4 levels (PAM4) was achieved for both upstream and downstream links.

Conclusions:

• The developed wide FOV OWC system effectively integrates with passive optical networks.
• The SLM-based beam steering provides a flexible and efficient solution for point-to-multipoint indoor communication.
• High-speed (25 Gbit/s PAM4) bi-directional data transmission is feasible in indoor OWC systems with wide FOV capabilities.