Scientists unlock new dimension in light manipulation, ushering a new era in photonic technology

Researchers at Heriot-Watt University have made a ground-breaking discovery paving the way for a transformative era in photonic technology.

For decades, scientists have theorised 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 School of Engineering and Physical Sciences in Edinburgh, Scotland.

The team’s breakthrough 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. These compounds are widely found in solar panels and touchscreens and can be shaped as ultra-thin films measuring just 250 nanometers (0.00025 mm),smaller than the wavelength of visible light.

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 radiating 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 particles of light, known as photons, a functionality which, up until now, had been unachievable.

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.

“It is difficult to grasp the advances we will experience in our daily lives as a result of this breakthrough,” explains Dr Ferrera.

“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: “Society is thirsty for bandwidth. 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.

“What science and technology is trying to do is emulate the human brain but by using electronic hardware. The materials we are working on are the ingredients towards this goal that can lower the energy consumption of these computational units, reducing costs and increasing processing power.”

Dr Wallace Jaffray, a postdoctoral research associate and Sven Stengel, a doctoral researcher, have been working alongside Dr Ferrera on the cutting-edge 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 a ‘fourth dimension’, enabling extraordinary light transformations, including amplification, the creation of quantum states, and new forms of light control.

Dr Ferrera continues: “Searching for a material that can drastically change under low-energy illumination in an ultra-fast manner has been the quest for the Holy Grail in all-optical technologies since the invention of laser.

“This new class of time-varying media is the biggest leap forward towards the perfect optically controllable material in decades enabling a large variety of novel and exciting effects that scientists all over the world are rushing to attempt. This is a new age in nonlinear optics which targets full light-control without the need of slow electric signals.”

The findings have been published in the peer reviewed journal, Nature Photonics.

Vladimir M. Shalaev, a Distinguished Professor of Electrical and Computer Engineering, Purdue University, 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.