Jessica Vermeer
24 September 2019

Researchers from Eindhoven University of Technology (TUE) have managed to reach data rates of 30 Gbit/s with Li-Fi, wireless communication by means of light. Their approach relies on a modulator to direct light scattered randomly from a wall towards detectors. The results are published in Nature Light: Science & Applications.

Wireless communication through light is challenging when there are obstacles between the transmitter and the receiver. If an optical beam hits a rough surface, the light is scattered. Diffused light reaches the receiver with much lower intensity. To date, the proposed solutions relied on increasing the system power to compensate for diffuse losses or on avoiding diffuse reflection altogether by using, for example, near-perfect mirrors as reflectors. Yet, the allowed power is limited by eye-safety regulations, while implementing mirrors is often costly and impractical.

TUE Li Fi
Credit: Eindhoven University of Technology

TUE researchers Zizheng Cao and Ton Koonen propose a solution based on enhancing the intensity of the diffused light by ‘wave-front shaping’. This technique allows light to be focused through and inside opaque materials by using a spatial light modulator (SLM). Using an SLM, different segments of the incident light can be modulated to maximize the intensity at the detector.

The net data rate of 30 Gbit/s may be further improved in the future, for example by using greater bandwidth. Employing photonic integrated circuit technology could reduce the cost of the proposed system.