Visible light communications (VLC) systems are an alternative to radio-based wireless networks and serve a dual purpose: They provide in-building lighting, and they use light waves for data transmission. VLC uses modulated light as a data carrier, while the visible spectrum provides light.
Using VLC for data transmission has some advantages. It offers decent bandwidth; it offers security because walls, floors and roofs obstruct the data-carrying wavelengths, which reduces the risk of eavesdropping; and it’s inexpensive since it’s simply incorporated into light fixtures or, in emerging developments, worked into displays and other surfaces.
To date, VLC devices have typically used light-emitting diodes (LED), mainly because LEDs are powerful light sources. Now, however, some researchers think that an organic variant of the LED, an OLED, would be a better way to go. OLEDs are cheaper and easier to distribute. They can be sprayed on, or delivered by inkjet technology, for example.
Significantly, point-to-point links using devices made of organic matter could solve some sustainability issues, according to the U.K.’s Newcastle University.
The tech industry has long wrestled with questions about how to encourage and make economical the recycling of hard-to-breakdown traditional electronics. LEDs are full of heavy metals, for example. Increasingly rapid lifecycle upgrades have exacerbated the challenges, and as IoT deployments expand, those questions could become even more pressing.
OLEDs could be a solution, but data rates haven’t been that great—they’re not as powerful. At Newcastle University, researchers believe a new type of OLED could enable the faster data speeds required in a VLC-driven IoT communications network. Significantly, the OLED would be sustainable, since OLEDs are natural, organic and free of eco-unfriendly heavy metals.
OLEDs have achieved around 10 Mbps speeds with add-on equalization algorithms and wavelength division multiplexing, whereas eco-unfriendly LEDs churn a healthy 35 Gbps. Equalization is a process where a specific band’s energy is increased or decreased to level things out and improve data rates and bandwidth.
The Newcastle University OLEDs provide 2.2 Mbps, which is plenty for many types of IoT sensors. Notably, the technology performs the transfers without the power-intensive, cumbersome equalization process. University researchers said they’re using new information modulation techniques that they developed in-house on Red to Near-Infra-Red (NIR) OLEDs.
“In recent years, the increasing demand for faster data transmission speeds has shifted the attention of researchers from bandwidth-limited radio technologies to optical wireless communication systems, which offer ‘practically’ unlimited bandwidth,” the researchers said in a press release.
One potential use-case is biosensing, where IoT sensors are implanted for active, real-time medical monitoring reasons, according to the scientists. The organic, polymer devices could also easily end up in VLC-based 5G access links and point-to-point communications for display technology, the teams suggests in a paper published in Nature’s Light: Science and Applications journal.
“… the use of organic light-emitting diodes (OLEDs) represents a valid alternative, which is gaining considerable attention for VLC,” the team writes.
“These are the highest rates ever reported for an online unequalized VLC link based on solution-processed OLEDs,” the researchers claim.