From “mini-earthquakes” to ultra-pure radio signals: University of Twente researchers advance photonic chip technology
Enschede, March 2026 — In a laboratory at the University of Twente, a long-standing limitation in photonic chip design has been addressed with a deceptively simple intervention: a thin layer of glass. The result, published in Nature Photonics, is a photonic chip capable of generating highly stable and spectrally pure radio signals by strengthening the interaction between light and sound by more than a factor of 200.
At the centre of the work is a phenomenon the researchers describe as “mini-earthquakes”—surface acoustic waves that travel along the chip and enable a more efficient coupling between optical and acoustic signals.
A problem decades in the making
The generation and filtering of radio-frequency signals sit at the heart of modern communication systems. Every mobile call, GPS signal or radar pulse depends on the ability to isolate specific frequencies from an increasingly crowded spectrum.
For decades, researchers have explored whether photonics—using light instead of electrical signals—could offer a more precise alternative. Light-based systems are inherently stable and can operate with lower noise. However, translating that advantage into radio-frequency applications requires a strong interaction between light and sound.
This interaction, known as Brillouin scattering, allows optical signals to generate and process radio frequencies through acoustic waves within a material. In practice, achieving this on a chip has proven difficult.
In silicon nitride—one of the most widely used materials in photonic integrated circuits—the interaction between light and sound is inherently weak. Previous attempts to overcome this limitation often relied on materials or structures that were difficult to scale or integrate into existing manufacturing processes.
A materials innovation rooted in compatibility
The University of Twente team approached the problem pragmatically. Rather than replacing silicon nitride, they enhanced it.
By adding a thin layer of tellurium oxide, a material already used in acousto-optic devices, the researchers enabled the formation of surface acoustic waves—vibrations that travel along the surface of the chip.
These waves play a crucial role. They ensure that the acoustic and optical signals remain spatially aligned, increasing the duration and strength of their interaction.
“The surface acoustic wave is the key to ensure the acoustic wave and optical wave overlap,” the researchers explain.
In addition, tellurium oxide responds more strongly to optical signals than silicon nitride. As the researchers note, it “has a much stronger compressive response to light… creating much stronger acoustics with the same intensity.”
The combined effect is a more than 200-fold increase in interaction strength, achieved without abandoning the silicon nitride platform that underpins much of today’s photonic infrastructure.
This choice is not incidental. As the researchers point out, compatibility with existing ecosystems is critical. New materials may offer performance gains, but if they require entirely new manufacturing processes, their practical adoption becomes significantly more complex.
What “ultra-pure” radio signals actually mean
One of the most notable outcomes of the work is the generation of highly stable, spectrally pure radio signals.
In conventional systems, radio signals are often derived from lower-frequency sources, which introduces noise. In this case, the signal is generated directly at the desired frequency through an acoustic process, reducing noise and improving stability.
“The radio signals become ultra-pure… due to the long acoustic lifetime and high acoustic frequency,” the researchers state.
This is not simply a matter of signal quality in abstract terms. Longer acoustic lifetimes mean that the waves persist for longer within the system, maintaining their phase and reducing fluctuations. In practical terms, this results in cleaner signals that are less prone to interference.
The researchers demonstrated this capability using a resonator smaller than half a millimetre, producing a radio tone comparable to systems that historically required much larger hardware.
Filtering in an increasingly crowded spectrum
Beyond signal generation, the technology enables highly selective filtering.
In modern communication systems, the radio spectrum is densely populated. Signals from different channels overlap, and devices must isolate the desired frequency while rejecting interference.
The Twente chip demonstrates the ability to isolate a single channel from a spectrum containing thousands, while remaining tunable across a wide frequency range.
This combination of selectivity and tunability is difficult to achieve with existing approaches. Current systems often rely on banks of filters, switching between them as needed.
A tunable filter with high resolution offers a more flexible alternative. It allows systems to adapt dynamically to changing conditions, rather than relying on fixed configurations.
“By having a frequency agile filter with high resolution it is possible to suppress strong interference signals with minimal distortion,” the researchers explain.
The engineering challenge: guiding light and sound together
Achieving this performance required solving a fundamental engineering problem: how to guide both light and sound within the same structure.
Materials that confine light effectively do not necessarily confine sound, and vice versa. The introduction of a soft tellurium oxide layer, combined with surface acoustic waves, provides a way to align the two.
This alignment ensures that the optical and acoustic signals interact over a longer distance, increasing efficiency and reducing loss.
Twente’s photonics ecosystem: from lab to industry
This breakthrough does not stand in isolation. It is part of a broader photonics ecosystem that has been developing in Twente over several decades.
As previously reported by MoveTheNeedle.news, the region has evolved into a centre of expertise in integrated photonics, with the University of Twente at its core. For start-ups, the University ensures access to specialised facilities and expertise, supporting the transition from research to real-world systems.
The ecosystem has already produced a number of notable spin-outs. QuiX Quantum, for example, is developing photonic quantum processors based on silicon nitride platforms, with the aim of building a universal photonic quantum computer.
Other startups, such as QSA Technology, are applying photonic chips to areas like quantum-secure authentication, illustrating how research in optics and materials is translating into diverse applications.
In this context, the latest research from the University of Twente reflects a broader trend: the maturation of photonics as both a scientific discipline and an industrial platform.
From demonstration to further development
The researchers emphasise that their work has undergone extensive validation. The publication process in Nature Photonics took more than 18 months, with reviewers requesting additional experiments and evidence.
According to first author Yvan Klaver, this process strengthened the results, as each round of feedback led to further improvements.
The current system represents a first demonstration of the concept. The team indicates that further development will focus on improving performance and integrating the technology into broader photonic systems.
This includes both enhancing the interaction further and exploring system-level applications that make use of the platform’s flexibility.
Precision as a defining requirement
What this work ultimately demonstrates is not a replacement for existing radio technologies, but a refinement.
As communication systems evolve, the ability to generate and filter signals with greater precision becomes increasingly important. This is particularly relevant in environments where the radio spectrum is densely used and interference is unavoidable.
By strengthening the interaction between light and sound on a chip, the University of Twente researchers have shown a way to achieve that precision within a compact, integrated platform.
In doing so, they contribute not only to the field of photonics, but also to a regional ecosystem that is establishing itself as one of Europe’s centres of expertise in advanced chip technologies.
Further reading on MoveTheNeedle.news:
The Dutch Startup Racing to Build a Universal Photonic Quantum Computer