Asymmetrical bidirectional VLC based on beam homogenizer OAM generation technology.

Area of Science:

• Optical Communications
• Wireless Networks
• Photonics

Background:

• Visible light communication (VLC) systems offer high bandwidth potential but face challenges in uplink capacity and multiplexing.
• Orbital Angular Momentum (OAM) offers a new degree of freedom for multiplexing in optical wireless communication systems.

Purpose of the Study:

• To develop an asymmetric bidirectional visible light communication (B-VLC) system.
• To implement orbital angular momentum (OAM) generation at the user terminal for uplink data transmission.
• To enhance uplink transmission capacity through OAM mode multiplexing.

Main Methods:

• Integration of beam homogenizers and a spatial light modulator (SLM) for OAM generation.
• Implementation of OAM mode multiplexing for uplink transmission.
• Validation using on-off keying (OOK) and quadrature phase-shift keying modulation schemes.

Main Results:

• Demonstration of an asymmetric B-VLC system over a 2m distance.
• Achieved downlink capacity of 2.2 Gbit/s using S-polarization.
• Uplink capacity enhancement by multiplexing four OAM channels (P-polarization), each reaching 800 Mbit/s.
• Bit error rates (BER) below the forward error correction limit for both uplink and downlink.

Conclusions:

• The proposed system effectively utilizes OAM generation for significantly enhanced uplink capacity in B-VLC.
• Simultaneous arbitrary generation of multiple OAM modes by a single SLM is feasible.
• The OAM multiplexing strategy provides a viable path for high-capacity optical wireless communication.