Researchers at Heriot-Watt University have demonstrated for the first time that light can be used to control every aspect of how electromagnetic waves oscillate — with no electronics required and at speeds 10,000 times faster than anything currently possible.
The discovery, published in leading global research journal Nature Photonics, could transform a range of cutting-edge fields, from quantum computing to life-saving drug development, and marks a significant leap forward in the emerging field of time-varying photonics.
The team, based at Heriot-Watt University’s Institute of Photonics and Quantum Sciences, within the School of Engineering and Physical Sciences, focused on “polarisation” — a key property of light that determines how it oscillates and, crucially, how it interacts with the physical world.
Dr Marcello Ferrera, Professor at Heriot-Watt University’s School of Engineering and Physical Sciences, said: “How light oscillates has a huge impact on how it interacts with the physical world around us. For the first time, we now have full control over this property of light, for any polarisation state, and at ultra-fast speeds.”
To achieve this level of control, the team designed an experiment using a very thin, transparent film made from aluminium zinc oxide — a material already widely used in technologies such as touchscreens and solar panels. Researchers fired an engineered burst of light onto the film lasting less than a trillionth of a second. During that fleeting moment, a second, carefully timed pulse of light passed through the film and had its behaviour shaped by the first.
Professor Ferrera offered a vivid analogy to explain the significance: “A simple way to picture this is to think about earthquakes. Some waves compress the ground, while others move it up and down. They are both waves, but their effects, and how they interact with the world, are completely different. In the same way, changing the polarisation of light can completely change how it behaves, including how it interacts with materials, carries information, or reveals details that would otherwise be invisible.”
The effects achieved were approximately one hundred thousand times stronger than anything previously recorded — a critical milestone for the field.
The real-world implications are substantial. Professor Ferrera highlighted two key areas: “One clear real-world example of where this matters is medicine. In fact, when synthesising a specific drug, polarised light is used to distinguish between mirror image molecules which have very different chemical reactions to our body. Another is in quantum computing. Because quantum technologies encode information in the polarisation of light, this type of ultrafast control has direct implications for faster and more flexible quantum communication systems, including highly secure data transmission.”
What sets this research apart is not just its speed, but its underlying approach. Professor Ferrera explained: “Until now, most photonics research has relied on materials that stay the same while light passes through them. What makes this different is that the material itself is changing while the light is travelling through it. That may sound subtle, but it fundamentally changes how we can manipulate light.”
He added: “This now opens up entirely new possibilities for future medical tools and next-generation quantum technologies which have been held back by this limitation previously.”
The study was led by Heriot-Watt researchers working alongside international partners at Purdue University’s Elmore Family School of Electrical and Computer Engineering, the University of Brescia, and the University of L’Aquila. Funding was provided by EPSRC, STFC (UK), AFOSR (USA), and NSERC (Canada).
The full research, titled All-optical polarization control in time-varying low index films via plasma symmetry breaking, is available in Nature Photonics.
