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The amount of data moving through our networks continues to grow, driven by applications such as video streaming, cloud computing, and artificial intelligence. Optical fiber provides the enormous capacity needed to handle this traffic, but installing new fiber connections can be expensive and disruptive. Wireless laser communication could offer an alternative. Instead of sending data through a physical cable, it uses narrow infrared laser beams to transmit information through the atmosphere. This combines the high capacity of optical communication with the flexibility of a wireless connection. The laser systems can also connect directly to existing fiber-optic networks. But there is a catch. Unlike a fiber, the atmosphere is not a stable communication channel.

The atmosphere becomes part of the network

Once the laser beam leaves the fiber, it has to travel through the open air. Fog, rain, snow, and haze can weaken the beam along its path. Even when the sky is clear, atmospheric turbulence can affect the connection. Turbulence occurs when air with different temperatures and densities mixes and moves. It can distort the laser beam in much the same way that hot air makes distant objects appear to shimmer. For a wireless laser connection, this can have serious consequences. The light arriving at the receiver needs to be focused into an optical fiber to recover the data. If turbulence changes the position or shape of the beam, some of the light may miss the fiber. The result can be a drop in signal strength or even an interrupted connection. Understanding these effects is therefore essential if wireless laser communication is to move beyond laboratory demonstrations.

From the lab to a 4.66-kilometer link

first studied individual atmospheric effects under controlled laboratory conditions. Several experimental setups were developed to reproduce atmospheric disturbances and investigate how they change the shape and strength of the laser beam. The laboratory made it possible to isolate individual effects and test potential solutions under controlled and repeatable conditions. But it could not show how an outdoor link behaves when weather and atmospheric conditions change naturally over days, weeks, and seasons. For that, the research moved outdoors. As part of the PhD project, the Reid Photonloop was established as a permanent 4.66-kilometer wireless laser link between the ºÚÁϸ£ÀûÍø campus and the High Tech Campus. Alongside the communication equipment, the link includes instruments that monitor weather, atmospheric turbulence, the light arriving at the receiver, and the fraction of that light that successfully enters the receiving fiber. This created a unique opportunity to study the communication channel itself while testing new technologies on a real urban link.

7.73 terabits per second

The results demonstrate just how much capacity can be achieved. By transmitting several colors of light simultaneously, the system reached a net data rate of up to 7.73 terabits per second over the 4.66-kilometer link. This is the highest data rate demonstrated to date over an urban wireless laser connection of this length. The result shows that wireless laser communication can provide multi-terabit connectivity across several urban kilometers — without requiring a physical fiber connection along the entire route. But the record speed is only one part of the story. A system that works extremely well for a short period is not necessarily useful as a practical communication link. Real networks need to operate as conditions change. That is why Van Vliet extended measurements beyond the approximately one-day periods commonly used in these experiments and collected data over several weeks. The full dataset covers July 2025 to July 2026, providing measurements across all four seasons.

Why does the connection fail?

The measurements revealed two main causes of signal loss. The first is weather. Fog, rain, snow, and haze can reduce the amount of laser light reaching the receiver. In sufficiently severe conditions, this can interrupt the connection. The second is more subtle. Even under clear conditions, atmospheric turbulence can distort the beam and prevent enough of the incoming light from entering the receiving fiber. The distinction matters because the two problems have different physical causes — and therefore require different solutions. To better understand turbulence, the research also used a specialized infrared imaging technique to visualize how the laser beam changes as it travels through the atmosphere. This provided a direct view of the distortions responsible for some of the communication impairments.

Making the receiver less dependent on perfect conditions

The thesis investigates several approaches to improving reliability. One receiver uses a fiber that collects light in six different spatial patterns. Instead of depending on the laser beam arriving at one precise position and with one precise shape, the receiver can capture the light in multiple ways. Under the assumptions investigated in the thesis, this reduced the estimated probability of a turbulence-related interruption by more than a factor of 1,000. Another approach spreads information over time. This allows the system to better cope with brief reductions in signal strength and recover information that might otherwise be lost.

From record speed to reliable connections

The research of Vincent van Vliet demonstrates that wireless laser communication can deliver extremely high data rates over several kilometers in an urban environment. The 7.73-terabit-per-second result shows the enormous capacity of the technology, while a full year of measurements provides a much better understanding of the atmospheric conditions that influence its performance. The Reid Photonloop will remain as a permanent platform for further research. It provides a real-world environment in which researchers can continue testing technologies for high-capacity wireless optical communication — and investigate how to make connections not only extraordinarily fast, but also reliable under changing conditions.

The research was carried out in the Electro-Optical Communication group within the Department of Electrical Engineering as part of the Dutch Research Council (NWO) project Optical Wireless Superhighways: Free Photons.

Read more on this research in these articles: /en/news-and-events/news-overview/10-04-2025-invisible-beams-of-light-above-eindhoven-provide-super-fast-wireless-data-transfer and .

This news has been covered by several national and international newspapers and media platforms, including:

- De Telegraaf

- Omroep Brabant

- Eindhovens Dagblad

- El Español

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Title of PhD thesis: . Supervisors: Prof. Chigo Okonkwo, and Dr. Eduward Tangdiongga. Other main parties involved: Aircision.