Li-Fi, a communication technology that uses visible light for data transmission, has the potential to surpass the speed of Wi-Fi by more than 100 times while offering a high bandwidth for transmitting large amounts of information simultaneously. One of the key advantages of Li-Fi is its ability to provide robust security by only transmitting data to areas that are illuminated by light. Additionally, Li-Fi takes advantage of existing indoor lighting infrastructure, such as LEDs, eliminating the need for separate installations. However, implementing visible light communication (VLC) in practical lighting systems has been a challenge due to issues of stability and accuracy in data transmission.
To address this challenge, a collaborative team led by Professor Dae Sung Chung from Pohang University of Science and Technology (POSTECH), along with researchers from Ajou University and Inha University, developed a novel light source to reduce interference and enhance the stability and accuracy of Li-Fi data transmission. Their findings were published in the journal Advanced Materials.
Interference occurs when light of the same wavelength intersects, leading to the merging or cancellation of amplitudes. This phenomenon was observed when using LEDs as a single-color light source in VLC technology. To overcome this issue, the team combined red, green, and blue organic light-emitting diodes (OLEDs) to create a composite white light source that minimizes interference zones while mimicking standard white illumination.
In addition, the team introduced a cavity structure to enhance the color representation of each wavelength in the OLEDs and incorporated a Fabry-Pérot structure into the light-absorbing organic photodiodes (OPDs) to selectively receive specific wavelengths of light.
The team’s composite white light source demonstrated a significantly lower bit error rate (BER) compared to conventional light sources. The BER quantifies the error ratio to the total transmitted bits and is a crucial measure of digital signal quality. The reduction of interference among light sources achieved by the new light source ensures more accurate transmission of information.
Professor Dae Sung Chung, the leader of the consortium, highlighted the advantages of their light source, stating, “Unlike conventional light sources, our light source, which combines three wavelengths, eliminates interference and enhances stability and accuracy in data transmission. We envision this technology as a potentially beneficial tool for various industries, serving as a next-generation wireless communication solution that utilizes existing lighting systems.”
In a multichannel VLC system, mixed white light is created by using red, green, and blue OLEDs with non-overlapping wavelengths to minimize interference among channels. The system utilizes light-absorbing organic photodiodes (OPDs) that selectively absorb specific wavelengths of light.
The development of this new light source brings Li-Fi technology one step closer to practical implementation in various settings, providing faster and more stable wireless data transmission using existing lighting infrastructure. With its potential to revolutionize wireless communication, Li-Fi could be a game-changer for industries that require high-speed data transmission and enhanced security.
