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Alexander Beadle is a science writer and editor for Technology Networks. He holds a masters degree in Materials Chemistry from the University of St Andrews, Scotland.
Mohsen Rahmani is a distinguished professor of optics and photonics and the leader of the Advanced Optics and Photonics Laboratory at Nottingham Trent University (NTU) in the UK. He obtained his PhD from the National University of Singapore in 2013, followed by a postdoc fellowship at Imperial College London and the Australian Research Council Early Career Fellowship at the Australian National University. In 2020, he joined NTU via the Royal Society Wolfson Fellowship. Shortly after moving to the UK, he was also awarded the UK Research and Innovation Future Leaders Fellowship. Recently, he has secured an ERC Consolidator Grant.
His research activities span over light-matter interactions with nanometre-scale particles for applications in flat optics, near-infrared imaging, bio-sensing, and reconfigurable optics. He has received several prestigious awards and prizes, including the Australian Eureka Prize, the Early Career Medal from the International Union of Pure and Applied Physics, and the Australian Optical Society Geoff Opat Award. Professor Rahmani has delivered 40+ invited talks, seminars, and keynotes at international conferences and has published more than 80 peer-reviewed journal papers. He is the past chair of the IEEE Nanotechnology Chapter across the UK and Ireland section (2021-2023) and a distinguished lecturer for the IEEE Nanotechnology Council 2024-2025. He is a fellow of the Institution of Engineering and Technology (IET).
Scientists have discovered a new technology that can control light in ways that traditional lenses and optical materials can’t.
As demonstrated in a new paper published in the journal Advanced Photonics Nexus, researchers from Nottingham Trent University (NTU) have developed a new optical focusing mechanism—a virtual metalens—that can be precisely tuned for better infrared (IR) imaging.
Traditionally, IR imaging has relied on special IR cameras that make use of narrow-bandgap semiconductors to visualize images. However, these cameras are constrained by this bandgap and so are only sensitive across certain chunks of the full IR range.
Recently, metamaterials—specifically, nonlinear metasurfaces—have been investigated as a way to “bend” light and turn invisible IR signals into visible images, allowing imaging to be done with conventional visible-light cameras. While this is a significant step forward and can enable broadband imaging, these physical metasurfaces—also known as metalenses—are inherently “fixed.” They operate using engineered nanomaterials, which, once built into the metalens, cannot change their shape.
In contrast, the new virtual metalens developed by the NTU team makes use of a spatial light modulator to effectively “tune” the metalens pixel-by-pixel, allowing the same device to perform many different functions. To learn more about the virtual metalens and the impacts this could have on infrared imaging, as well as the wider spheres of optics and microscopy, Technology Networks spoke with study author Prof. Mohsen Rahmani, a distinguished professor of optics and photonics at NTU.
Alexander Beadle is a science writer and editor for Technology Networks. He holds a masters degree in Materials Chemistry from the University of St Andrews, Scotland.
Mohsen Rahmani is a distinguished professor of optics and photonics and the leader of the Advanced Optics and Photonics Laboratory at Nottingham Trent University (NTU) in the UK. He obtained his PhD from the National University of Singapore in 2013, followed by a postdoc fellowship at Imperial College London and the Australian Research Council Early Career Fellowship at the Australian National University. In 2020, he joined NTU via the Royal Society Wolfson Fellowship. Shortly after moving to the UK, he was also awarded the UK Research and Innovation Future Leaders Fellowship. Recently, he has secured an ERC Consolidator Grant.
His research activities span over light-matter interactions with nanometre-scale particles for applications in flat optics, near-infrared imaging, bio-sensing, and reconfigurable optics. He has received several prestigious awards and prizes, including the Australian Eureka Prize, the Early Career Medal from the International Union of Pure and Applied Physics, and the Australian Optical Society Geoff Opat Award. Professor Rahmani has delivered 40+ invited talks, seminars, and keynotes at international conferences and has published more than 80 peer-reviewed journal papers. He is the past chair of the IEEE Nanotechnology Chapter across the UK and Ireland section (2021-2023) and a distinguished lecturer for the IEEE Nanotechnology Council 2024-2025. He is a fellow of the Institution of Engineering and Technology (IET).
Metasurfaces are arrays of engineered nanomaterials that are often hundreds of times thinner than a human hair. They can replicate the functions of bulky optical elements such as mirrors and prisms, enabling further miniaturisation of many of today’s gadgets, such as cameras.
In addition, the properties of nanomaterials used in metasurfaces can be tuned to some extent by external stimuli, such as applying a voltage or changing the temperature. As a result, metasurfaces can tune their functions, an ability that regular optical elements cannot do. For example, the focal length of a regular lens cannot be adjusted, whereas that of a metasurface lens can be tuned to some extent.
Alexander Beadle is a science writer and editor for Technology Networks. He holds a masters degree in Materials Chemistry from the University of St Andrews, Scotland.
Mohsen Rahmani is a distinguished professor of optics and photonics and the leader of the Advanced Optics and Photonics Laboratory at Nottingham Trent University (NTU) in the UK. He obtained his PhD from the National University of Singapore in 2013, followed by a postdoc fellowship at Imperial College London and the Australian Research Council Early Career Fellowship at the Australian National University. In 2020, he joined NTU via the Royal Society Wolfson Fellowship. Shortly after moving to the UK, he was also awarded the UK Research and Innovation Future Leaders Fellowship. Recently, he has secured an ERC Consolidator Grant.
His research activities span over light-matter interactions with nanometre-scale particles for applications in flat optics, near-infrared imaging, bio-sensing, and reconfigurable optics. He has received several prestigious awards and prizes, including the Australian Eureka Prize, the Early Career Medal from the International Union of Pure and Applied Physics, and the Australian Optical Society Geoff Opat Award. Professor Rahmani has delivered 40+ invited talks, seminars, and keynotes at international conferences and has published more than 80 peer-reviewed journal papers. He is the past chair of the IEEE Nanotechnology Chapter across the UK and Ireland section (2021-2023) and a distinguished lecturer for the IEEE Nanotechnology Council 2024-2025. He is a fellow of the Institution of Engineering and Technology (IET).
External stimuli can only slightly change the properties of nanomaterials (within the metasurfaces). Therefore, the tunability of metasurface functions is very limited.
In this paper, we introduce a new type of metasurface that is no longer made of physical nanomaterials. Instead, we use a thin film as a medium and generate some optical patterns in the shape of metasurfaces on it. Whilst this configuration can act as a metasurface, those optical patterns can be replaced in the time it takes to blink an eye. Therefore, virtual metasurfaces can offer distinct functions nearly instantaneously. In this way, we overcome the limitation of tuning the physical metasurfaces.
Our paper demonstrates just one example of this capability. We show how interchangeable virtual metasurfaces not only change the frequency (color) of light from infrared (invisible to the eye) to visible light, but also focus it at distinct focal lengths on demand. Such a proof of concept demonstrates the potential to change the paradigm of IR imaging, paving the way for integrated IR imaging capability in our personal electronic devices.
Alexander Beadle is a science writer and editor for Technology Networks. He holds a masters degree in Materials Chemistry from the University of St Andrews, Scotland.
Mohsen Rahmani is a distinguished professor of optics and photonics and the leader of the Advanced Optics and Photonics Laboratory at Nottingham Trent University (NTU) in the UK. He obtained his PhD from the National University of Singapore in 2013, followed by a postdoc fellowship at Imperial College London and the Australian Research Council Early Career Fellowship at the Australian National University. In 2020, he joined NTU via the Royal Society Wolfson Fellowship. Shortly after moving to the UK, he was also awarded the UK Research and Innovation Future Leaders Fellowship. Recently, he has secured an ERC Consolidator Grant.
His research activities span over light-matter interactions with nanometre-scale particles for applications in flat optics, near-infrared imaging, bio-sensing, and reconfigurable optics. He has received several prestigious awards and prizes, including the Australian Eureka Prize, the Early Career Medal from the International Union of Pure and Applied Physics, and the Australian Optical Society Geoff Opat Award. Professor Rahmani has delivered 40+ invited talks, seminars, and keynotes at international conferences and has published more than 80 peer-reviewed journal papers. He is the past chair of the IEEE Nanotechnology Chapter across the UK and Ireland section (2021-2023) and a distinguished lecturer for the IEEE Nanotechnology Council 2024-2025. He is a fellow of the Institution of Engineering and Technology (IET).
IR light is invisible to the human eye but carries valuable information for night vision, non-destructive medical imaging, food and agrochemical quality control, and thermal imaging.
Today’s IR cameras use semiconductor detectors with specific bandgaps that absorb select bands of IR light. As a result, they are complex and expensive, and they work only within a specific IR band (enabling only certain applications). Therefore, for example, the IR cameras used for night vision cannot be used for medical imaging or agriculture, and vice versa.
However, the platform demonstrated in our paper works differently. It is no longer limited by semiconductor band gaps. It operates via virtual metasurfaces that can readily control the input and output frequencies (=colors) at any arbitrary focal length. So a universal device can be used to image many IR bands, with much simpler and cheaper optics.
Figure 1: Associate professor Lei Xu (L) and research fellow Dr. Ze Zheng (R), two members of the core laboratory research team and co-authors of the paper, in the laboratory. Credit: Nottingham Trent University.
Alexander Beadle is a science writer and editor for Technology Networks. He holds a masters degree in Materials Chemistry from the University of St Andrews, Scotland.
Mohsen Rahmani is a distinguished professor of optics and photonics and the leader of the Advanced Optics and Photonics Laboratory at Nottingham Trent University (NTU) in the UK. He obtained his PhD from the National University of Singapore in 2013, followed by a postdoc fellowship at Imperial College London and the Australian Research Council Early Career Fellowship at the Australian National University. In 2020, he joined NTU via the Royal Society Wolfson Fellowship. Shortly after moving to the UK, he was also awarded the UK Research and Innovation Future Leaders Fellowship. Recently, he has secured an ERC Consolidator Grant.
His research activities span over light-matter interactions with nanometre-scale particles for applications in flat optics, near-infrared imaging, bio-sensing, and reconfigurable optics. He has received several prestigious awards and prizes, including the Australian Eureka Prize, the Early Career Medal from the International Union of Pure and Applied Physics, and the Australian Optical Society Geoff Opat Award. Professor Rahmani has delivered 40+ invited talks, seminars, and keynotes at international conferences and has published more than 80 peer-reviewed journal papers. He is the past chair of the IEEE Nanotechnology Chapter across the UK and Ireland section (2021-2023) and a distinguished lecturer for the IEEE Nanotechnology Council 2024-2025. He is a fellow of the Institution of Engineering and Technology (IET).
The 19th century was known as the century of revolution in mechanical engineering, with advances in engines and motors. The 20th century was known as the century of revolution in electronics, with advances in electronic devices and computers. Many consider the 21st century the century of the optical revolution, as nothing can match the speed of light or light's capacity to carry information.
Metasurfaces are seen as the backbone of this optical revolution. Metasurfaces can offer many applications in imaging and microscopy, optical and quantum computing, as well as bio-chemical sensing. The concept of virtual metasurfaces, presented in our paper, is extendible to all these applications.
Alexander Beadle is a science writer and editor for Technology Networks. He holds a masters degree in Materials Chemistry from the University of St Andrews, Scotland.
Mohsen Rahmani is a distinguished professor of optics and photonics and the leader of the Advanced Optics and Photonics Laboratory at Nottingham Trent University (NTU) in the UK. He obtained his PhD from the National University of Singapore in 2013, followed by a postdoc fellowship at Imperial College London and the Australian Research Council Early Career Fellowship at the Australian National University. In 2020, he joined NTU via the Royal Society Wolfson Fellowship. Shortly after moving to the UK, he was also awarded the UK Research and Innovation Future Leaders Fellowship. Recently, he has secured an ERC Consolidator Grant.
His research activities span over light-matter interactions with nanometre-scale particles for applications in flat optics, near-infrared imaging, bio-sensing, and reconfigurable optics. He has received several prestigious awards and prizes, including the Australian Eureka Prize, the Early Career Medal from the International Union of Pure and Applied Physics, and the Australian Optical Society Geoff Opat Award. Professor Rahmani has delivered 40+ invited talks, seminars, and keynotes at international conferences and has published more than 80 peer-reviewed journal papers. He is the past chair of the IEEE Nanotechnology Chapter across the UK and Ireland section (2021-2023) and a distinguished lecturer for the IEEE Nanotechnology Council 2024-2025. He is a fellow of the Institution of Engineering and Technology (IET).
The transition from physical to virtual (i.e., digital) metasurfaces opens the door to fully integrating artificial intelligence (AI) in this direction.
By now, the metasurfaces community has used AI for designing and modeling metasurfaces, pre-processing and/or data post-processing. However, the virtual metasurface platform enables the use of AI during experiments, providing instant improvements in results.
Reference: Zheng Z, Sergaeva O, Rocco D, et al. Nonlinear virtual lens for programmable and multispectral infrared upconversion imaging. Adv Photon Nexus. 2026;5(04). doi: 10.1117/1.APN.5.4.046024
This paper was published in collaboration with researchers at the University of Brescia in Italy and Nankai University in China. The team, based in NTU's Advanced Optics and Photonics (AOP) Laboratories, was supported by the UK Research and Innovation Future Leaders Fellowship and the European Research Council Consolidator Grant.
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Alexander is a science writer and editor for Technology Networks. He writes news and features for the Applied Sciences and Analysis & Separations communities, leading the site's coverage of topics relating to environmental science, food and beverage analysis, and analytical techniques.
Before joining Technology Networks, Alexander worked as a freelance science writer. He holds a masters degree in Materials Chemistry from the University of St Andrews, Scotland.
Mohsen Rahmani is a distinguished professor of optics and photonics and the leader of the Advanced Optics and Photonics Laboratory at Nottingham Trent University (NTU) in the UK. He obtained his PhD from the National University of Singapore in 2013, followed by a postdoc fellowship at Imperial College London and the Australian Research Council Early Career Fellowship at the Australian National University. In 2020, he joined NTU via the Royal Society Wolfson Fellowship. Shortly after moving to the UK, he was also awarded the UK Research and Innovation Future Leaders Fellowship. Recently, he has secured an ERC Consolidator Grant.
His research activities span over light-matter interactions with nanometre-scale particles for applications in flat optics, near-infrared imaging, bio-sensing, and reconfigurable optics. He has received several prestigious awards and prizes, including the Australian Eureka Prize, the Early Career Medal from the International Union of Pure and Applied Physics, and the Australian Optical Society Geoff Opat Award. Professor Rahmani has delivered 40+ invited talks, seminars, and keynotes at international conferences and has published more than 80 peer-reviewed journal papers. He is the past chair of the IEEE Nanotechnology Chapter across the UK and Ireland section (2021-2023) and a distinguished lecturer for the IEEE Nanotechnology Council 2024-2025. He is a fellow of the Institution of Engineering and Technology (IET).
Kate graduated from Sheffield Hallam University with a bachelor's degree in biomedical sciences in 2020. During her studies, she developed a passion for science communication and after graduating, began a science blog in order to continue writing about trending science news and topics of interest. She joined the editorial team at Technology Networks in 2021. In her role as science editor Kate supports the publication’s in-house writers, produces scientific content across all communities and works closely with the managing editor to help coordinate commissioned pieces.
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