Heriot-Watt scientists unlock new dimension in light control: time

18 Mar 2025

Following experiments with transparent conducting oxides; glass that alters how light travels through it.

Researchers at Heriot-Watt University, Edinburgh, UK, have made what they are calling “a ground-breaking discovery paving the way for a transformative era in photonic technology.”

For decades, scientists have theorized the possibility of manipulating the optical properties of light by adding a new dimension – time. This once-elusive concept has now become a reality thanks to nanophotonics experts from the university’s School of Engineering and Physical Sciences.

The achievement emerged from experiments with nanomaterials known as transparent conducting oxides (TCOs) – a special glass capable of changing how light moves through the material at incredible speeds. The findings have been published in the peer reviewed journal, Nature Photonics.

These compounds are widely found in solar panels and touch screens and can be shaped as ultra-thin films measuring just 250 nm. Led by Dr. Marcello Ferrera, Associate Professor of Nanophotonics, the Heriot-Watt research team, supported by colleagues from Purdue University in the US, managed to sculpt the way TCOs react by irradiating the material with ultra-fast pulses of light. Remarkably, the resulting temporally engineered layer was able to simultaneously control the direction and energy of individual photons, a functionality which, up until now, had been unachievable.

High-speed data processing

The discovery is directly linked to the possibility of processing data at a far greater speed and volume than what is currently available. It is expected to have transformative impact in several key areas such as optical computing and AI, integrated quantum technologies, and ultra-fast physics.

Dr. Ferrera commented, “By using a nonlinear material to fully exploit optical bandwidth, companies and major organisations can process so much more information. This will hold huge benefits to the likes of data centres and advancing AI technology, among others, and will underpin exciting new technologies we cannot fully understand at this time.”

Commenting further on the potential future uses arising from this research, Dr. Ferrera said, “If we are aiming at making a virtual meeting a fully immersive 3D experience, this would demand enormous computational power and processing speed, which only ultra-fast all-optical components can provide. The material properties we are investigating here could increase computational speed by several orders of magnitude, enabling handling much greater volumes of information at a fraction of current energy expenditure.

Dr. Wallace Jaffray, a postdoctoral research associate and Sven Stengel, a doctoral researcher, have been working alongside Dr. Ferrera on the research at Heriot-Watt University. The core of their breakthrough lies in the ability to manipulate TCOs to control the speed at which photons travel. This newfound capacity effectively adds what the team calls a “fourth dimension”, enabling extraordinary light transformations, including amplification, the creation of quantum states, and new forms of light control.

Vladimir Shalaev, a Professor of Electrical and Computer Engineering, at Purdue, who assisted in the research said, “These low-index transparent conductors have brought a real revolution within the field of integrated nonlinear optics, allowing for the effective and energy-efficient manipulation of optical signals on unprecedentedly short time scales.”

Alexandra Boltasseva, a Distinguished Professor of Electrical and Computer Engineering at Purdue University, added, “Our common research effort demonstrates that with these materials we can finally use the variable of time for engineering the optical properties of compounds beyond what is currently possible by using standard fabrication processes.” Dr. Ferrera was recently awarded a share of £6.5m from the UK-Canada Quantum for Science Research Collaboration to advance his research over the next two years.