Heriot-Watt team achieves a revolution in photonics

The Herald Scotland

11-05-2025

This is a phenomenally specialist area of scientific endeavour, and to be entirely honest I was worried that I just wouldn't be able to get my around it; phoning an editor to tell them a story has fallen through is one thing, but having to admit that it has happened because you're not clever enough to understand what on earth is going on is something else entirely.
But that phone call wasn't necessary because Dr Ferrera, somehow, found a way to help a man with a degree in poems and Frankenstein get to grips with nanophotonics, transparent conducting oxides, and – this isn't a joke – temporal engineering.
This whole discovery is about being able to manipulate particles of light, but at the most basic level we're (apparently) talking about making waves do things. The trouble is that this is hard for people to conceptualise when we're talking about light waves, but Dr Ferrera encouraged me to start working it all out by thinking instead of sound.
If you've ever been in a recording studio you'll have seen the different kinds of materials on the walls and ceilings, all of which are designed to make the room – and subsequent recordings – sound a certain way. That happens because we know how to use static materials to change the behaviour of sound waves.
We can also do this dynamically, which actually means adding time to the equation. By developing materials that can vibrate to match sound waves, we have been able to, for example, produce readily available noise-cancelling headphones.
So far, so simple…ish.
But what about light, which is both a wave and a particle (known as a photon)?
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Well we can certainly manipulate light using static materials that do a similar job to the panels in the recording studio, but doing this dynamically has remained an elusive, theorised, but potentially world-changing possibility.
Until now?
It may sound an exaggeration, but what this team at Heriot-Watt has discovered really could change the world.
The Heriot-Watt University laboratory where Dr Ferrera and his team work. (Image: James McEnaney) Their major breakthrough came about thanks to experiments with those aforementioned transparent conducting oxides, which are a special type of glass that can be used to manipulate the behaviour of light. The compounds can be made incredibly thin – thinner, in fact, than the wavelength of visible light – but are widely used in everyday life. You've seen solar panels that use them, and may well be reading this on a touchscreen phone that incorporates the technology.
Dr Ferrera's team has basically managed to find a way to control the reaction of this type of material in order to control both the direction and the energy of photonic particles.
The findings have been published in the peer reviewed journal, Nature Photonics, and attracted attention from around the world.
It has been a collaborative effort. Professors Alexandra Boltasseva and Vladimir M. Shalaev from Purdue University in the USA were involved in material synthesis, while Professor Andrea Di Falso of St Andrews University was responsible for device fabrication. Alongside Dr Ferrera were Dr Wallace Jaffray, a postdoctoral researcher, and PhD candidate Mr Sven Stengel.
But how does impossibly thin glass that guides photons change the world?
Well, for one thing, it could allow for a transformation in the speed at which devices are able to process data. Dr Ferrera explained to me that, while this isn't necessary for handheld or household devices (for which electrons are sufficient) it could completely revolutionise high-powered computing systems.
One of the more obvious areas in which this could have major consequences is artificial intelligence. At present, the expansion of this technology is being driven by the consumption of incredible amounts of energy and water, making the systems inherently, even dangerously, inefficient. Optical computing, I'm told, would make the data-centres that sit behind this sort of technology not just cheaper, but much more environmentally friendly.
And there's more. Dr Ferrera explains that, eventually, these technologies are going to hit a hard barrier that electrical computing simply cannot overcome, which will make it impossible to create neural nets that really do work like human brains. An optical computer, however, could obliterate those barriers. This is just one example from a list that is only likely to get longer over time.
So, what happens next? Part of the reason that the breakthrough by the Heriot-Watt team is so important is that the materials they are using are readily available, which means it will be possible for lots of different teams in lots of different countries to start their own experiements.
'It's not a material that we are the only ones in the world to have access to,' Dr Ferrera explains. 'So it will be a global effort to further develop this technology.'
'And in my opinion it's going to go very, very fast.'