In a Swedish lab, scientists have done something that could ripple across the world’s communication networks. They’ve built a chip—a sliver of silicon nitride etched with microscopic spirals—that promises to send data ten times faster than today’s best optical amplifiers.
Of course, the breakthrough doesn’t lie in making light travel faster. Thanks to physics, that’s firmly off the table. Instead, the team at Chalmers University of Technology expanded the spectrum (the range of colors of light) used to transmit information. The result is a new kind of laser amplifier with the broadest continuous bandwidth ever recorded for a silicon chip, an engineering feat that could reshape internet infrastructure, medical diagnostics, and even deep space communications.
“Our amplifier boasts a bandwidth of 300 nanometers, enabling it to transmit ten times more data per second than those of existing systems,” said Peter Andrekson, professor of photonics at Chalmers and the study’s senior author.
The Bottleneck in the Fiber-Optic Era
Everything on the modern internet ultimately rides on pulses of laser light traveling through glass fiber. These pulses are boosted by optical amplifiers, devices that strengthen faint light signals as they traverse oceans and continents.
Today’s optical amplifiers have a typical bandwidth of about 30 nanometers. That means they can handle only a narrow slice of the light spectrum at a time. With data traffic expected to double by 2030, according to Nokia Bell Labs, these limitations are starting to show.
To solve this conundrum, the Chalmers team looked to four-wave mixing, a nonlinear optical phenomenon that can combine and redistribute light frequencies in elegant and powerful ways. But making it work reliably over a large bandwidth had stumped researchers for years.
“Conventional designs for wideband amplification often result in multi-mode operation,” the team wrote in their April 2025 Nature paper. Multiple modes mean multiple ways light can travel through a waveguide, creating interference that degrades the signal. “We present a methodology for fabricating nonlinear waveguides with simultaneous single-mode operation and anomalous dispersion,” they added.
In simpler terms, they’ve made a single-lane highway for light that stretches far across the spectrum, reducing the “traffic jams”.
The Secret Is in the Spirals
At the core of the breakthrough is a silicon nitride chip etched with tightly coiled waveguides. These spiral paths allow the chip to maintain a single mode of light while also achieving what physicists call “anomalous dispersion”—a condition necessary for efficient four-wave mixing.
The engineers adjusted the shape and curves of tiny spiral paths on the chip to control how light moves through them. They also made precise tweaks to how the chip handles different colors of light. These changes helped the chip send a much wider range of light signals, allowing it to carry more data at once.
“This capability allows it to amplify very weak signals, such as those used in space communication,” Andrekson noted.
A Chip-of-All-Trades
The chip isn’t just fast—it’s small and sensitive. At less than a few centimeters long, it can be integrated into compact devices. That opens the door to wide-ranging applications from real-time medical imaging to ultra-efficient lasers for industrial inspection. Because of its large bandwidth, the amplifier could also provide more precise imaging of tissues and organs, helping doctors detect diseases earlier.
“Minor adjustments to the design would enable the amplification of visible and infrared light as well,” Andrekson said. “This means the amplifier could be utilized in laser systems for medical diagnostics, analysis, and treatment.”
In tests, the amplifier handled 100 gigabit-per-second data streams without breaking a sweat. The researchers successfully used it to convert laser signals across more than 200 nanometers of wavelength, far beyond the C and L bands that dominate today’s fiber-optic systems.
Their chip managed this all-optically, without converting light to electricity and back. That’s critical for reducing latency and energy use in next-generation data centers and AI systems.
Looking Ahead: More Data, Fewer Limits
The Chalmers amplifier now holds the record for bandwidth among continuous-wave optical amplifiers. But the team believes they can push it further.
They’re already testing longer versions of the waveguides, and future designs may stack multiple spiral layers on a single wafer. That would allow for even more dispersion control, higher gain, and broader compatibility across the light spectrum.
This is more than just a technological upgrade, it’s a rethinking of what’s possible with light. By coaxing more data from every photon, the Chalmers team has built a chip that could help keep our hyperconnected world from crashing under the weight of its own information.
And it all fits in something smaller than a fingernail.
