A model of orbital angular momentum Li-Fi

TL;DR

This paper introduces a novel visible light communication system that combines color and orbital angular momentum to significantly increase data capacity and security, demonstrated through indoor transmission of images and audio with high fidelity.

Contribution

The work presents a new RGB-OAM hybrid coding scheme for Li-Fi that enhances data capacity and security using a combination of color channels and OAM states.

Findings

Successful transmission of color images and audio with over 96% fidelity

Demonstrated increased information capacity through hybrid RGB-OAM encoding

Enhanced security features in visible light communication systems

Abstract

Twisted light has recently gained enormous interest in communication systems. Thus far, twisted light has not yet been utilized for visible light communication to transmit data. Here, by exploiting the color and orbital angular momentum (OAM) degrees of freedom simultaneously, we construct a much higher-dimensional space spanned by their hybrid mode basis, which further increases the information capacity of twisted light. We build a new visible light communication system using a white light emitting diode, with red, green and blue (RGB) colors serving as independent channels and with OAM superposition states encoding the information. We connect our conceptually new RGB-OAM hybrid coding with the specially designed two-dimensional holographic gratings based on theta-modulation. After indoor free-space transmission, we decode the color information with an Xcube prism and subsequently decode the OAM superposition states with a pattern recognition method based on supervised machine learning. We succeed in demonstrating the transmission of color images and a piece of audio with the fidelity over 96%. Our point-to-point scheme with hybrid RGB-OAM encoding, not only increases significantly the information capacity of twisted light, but also offers additional security that supplements the traditional broadcasting visible light communications, e.g., Li-Fi.