Emerging from the 2000 degree C furnace, a fibre 'stack' guides light even while it is being drawn.
Credit: Dr Nathan Roberts
Scientific Frontline: "At a Glance" Summary: Twisted Optical Fibers
- Main Discovery: A novel fiber-based photonic topological insulator ensures uninterrupted light propagation, bypassing physical defects, twists, and bends without signal scattering or leakage.
- Methodology: Researchers engineered an optical fiber with multiple light-guiding cores using standard telecommunication-grade materials and introduced a continuous, controlled physical twist during the standard high-temperature drawing process.
- Key Data: Drawn from a 2000-degree Celsius furnace, the engineered design marks the first successful demonstration of an optical fiber featuring two-dimensional topologically protected light guidance.
- Significance: The induced topological behavior isolates light within protected states, preventing unwanted channel coupling and backward reflection caused by microscopic glass imperfections, thereby drastically enhancing overall signal robustness.
- Future Application: The technology is structurally optimized for mass-produced, high-capacity data center interconnects, advanced quantum communications, and precision sensing instruments utilized in medical imaging and environmental monitoring.
- Branch of Science: Photonics, Condensed Matter Physics, and Telecommunications Engineering.
- Additional Detail: The twisted multi-core fiber retains the physical flexibility and low-loss transmission properties of conventional optical cables and integrates seamlessly into current manufacturing techniques, overcoming the restrictive size limitations of previous solid-state topological materials.
Light powers everything from communications to sensing, yet even tiny imperfections can scatter it and weaken signals. To address this, a team led by the University of Bath – working with the University of Cambridge and international partners – has developed a new structure that keeps light flowing smoothly even through bends, twists or damage, with the potential to operate over unprecedented distances.
This new fiber-based photonic topological insulator provides protected pathways that keeps light flowing in the intended direction rather than scattering.
These features make it a strong candidate for:
- The ultra-reliable light-based connections needed to transmit data between chips, devices or electronic components, and
- Directing light signals in advanced communications (such as high-bandwidth or even quantum communications), precision sensing (including in medical imaging and environmental monitoring) and emerging quantum technologies, where uninterrupted, stable light flow is essential.
The researchers found that by using standard telecom grade materials to create an optical fibre with multiple light-guiding cores, and then introducing a simple twist during fabrication, they could form a pathway that remains resilient to defects and disorder, ensuring light continues to propagate smoothly.
Robust signal transmission
Conventional optical fiber used in telecommunications guides light along a single core, allowing it to travel freely in two directions – forwards and backwards. Any tiny imperfection in the glass core can scatter the light, either leaking it out of the fiber or reflecting it backwards from the intended direction of travel. This can degrade or even destroy the signal.
Adding more cores can, in principle, create additional channels for carrying more data but, in practice, light tends to ‘couple’ between neighboring cores. This mixes channels, introduces noise and limits how much information a multi-core fiber can reliably carry.
The new twisted fiber avoids these problems. Its many cores, combined with a built-in twist, creates special protected states of light that naturally follow the twist and avoid coupling into other cores. When the light meets a defect, it simply flows around it instead of scattering. As a result, signal transmission has the potential to be far more robust.
Because the twist is added during the normal manufacturing steps that fibre fabricators already use, no special processing is required. The resulting fiber therefore shares many of the characteristics of a standard optical fiber. It:
- Can be produced in extended lengths – unlike existing materials used for topological insulators, which are typically limited to small pieces of solid material
- Remains flexible
- Transmits light with minimal loss
In short, this technique is fully compatible with existing fibre production methods while adding resilience to defects.
State-of-the-art optical labs
Following extensive design and simulation work, the topological fibre was fabricated in the Centre for Photonics at the University of Bath and tested in the university’s state-of-the-art optics labs.
Study co-author Dr Peter Mosley, from the Department of Physics at Bath, said: “By adding a controlled twist as the fiber is created, we’re able to induce topological behavior that lets light flow around defects rather than scatter from them. It’s a clean, scalable way to build robustness into photonic interconnects.
“This is the first demonstration of an optical fiber with two-dimensional topologically protected light guidance. Even though we used only short lengths of fiber for this demonstration, our work shows a path toward protecting signals in mass produced optical fibers that could be used in large data center networks.”
Dr Anton Souslov, associate professor at the Cavendish Laboratory at the University of Cambridge and study co-author said: “Topological states of light have many potential uses in communications and quantum technologies, and it is exciting to see them realized in such a scalable and ready-to-use platform as optical fiber. Going forward, I am especially interested in the variety of yet-unexplored topological phenomena that optical fibre is uniquely able to demonstrate.”
Published in journal: Nature Photonics
Title: Twisted optical fibres as photonic topological insulators
Authors: Nathan Roberts, Brook Salter, Jack Binysh, Peter J. Mosley, and Anton Souslov
Source/Credit: University of Bath
Reference Number: phy022426_01
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