The industry’s most innovative people 2024 Ventsislav Valev


Organisation: University of Bath Role: Head of Department of Physics & Research Fellow of the Royal Society Based in: Bath, UK Education: PhD in Physics, Radbound University Nijmegen


What are you currently working on? What will the impact be? Our current work investigates the chirality transfer between molecules and nanoparticles – the first step in human-made self-assembly. Chirality – a sense of twist – is a fundamental property of life. Its significance spans from the evolution of humans to cutting-edge nanotechnology. It helps guide the self-assembly of molecules at the nanoscale through levels of increasing organisational complexity that results in the diversity of living beings. Human-made nanotechnology seeks to emulate these processes for a multitude of applications. However, our grasp of the rules that govern chirality transfer remains in its infancy, demanding innovative approaches to directly explore the interfaces, where the transfer operates. We build unique optical experiments, using innovative, award-winning physical methods recently discovered in our team, which had eluded scientists for over 40 years. Now, we aim to demonstrate yet another, important, new physical effect that was predicted 45 years ago. We also seek to increase the sensitivity of the new effects using quantum optical methods (by building and integrating a squeezed light source). At the level of fundamental science,


together with new fundamental particles, new physical laws and new physical constants, new physical effects are among the most significant scientific advances. Our success would therefore have clear scientific impact in nonlinear photonics. In addition, we expect that our work will help reshape several scientific areas: in nanoscience, it could help to establish novel material principles; in synthetic biology, it could contribute to refining self-assembly techniques; in chemistry, it could enable more efficient high-throughput synthesis; and in pharmaceutical science, it could gain new tools for drug discovery.


What was the most surprising thing you found in the course of your latest research? In 1979, David Andrews theorised that chiral molecules will influence nonlinear optical effects. His work included a formula that described a new physical effect – chiroptical harmonic scattering (CHS). The idea was that upon illuminating chiral molecules with circularly polarised light, the chirality of the scatterers would be expressed in the


observation. Such events are rare but, what makes this one exceptional is that theorist and experimentalist then joined forces to make further discoveries. This remarkable convergence of theory and experimentation was distinguished with awards from the Royal Society of Chemistry (in 2022) and from the Institute of Physics (in 2023). Both the science and the human adventure were very unexpected for me.


What’s your biggest research priority in the coming year?


"We expect that our work will help reshape several scientific areas: in nanoscience… synthetic biology… chemistry… and in pharmaceutical science"


intensity of light scattered at the second- harmonic frequency. Although this was the most direct expression of chirality in nonlinear optics, an experimental observation eluded scientists for decades. In 2019, our team demonstrated the CHS experimentally, thereby answering the four-decades-long scientific question. Subsequent confirmatory experimental evidence quickly followed. What was very surprising to me is that we then proceeded to show the same kind of effects at the third-harmonic frequency as well. Second- and third-harmonic effects are usually very different, with different origin and selection rules. There was no theory to guide us on the third-harmonic work, and so it was a great privilege for me to have none other than Andrews himself joining our research efforts and writing new theory. It is always a precious moment in science, when decades-old theory meets experimental


Our priority is to demonstrate that the nonlinear chiroptical scattering effects we discovered (and those that we still aim to demonstrate) are general. For this purpose, we are looking for a variety of physical systems (nanoparticles, quantum dots, nanocrystals, clusters, polymers, molecules, hybrid materials, etc.) where we aim to record the effects. There have been decades between theory and first experiments, so we need to be realistic about the timescale of commercialisation. However, we are constantly improving our experimental equipment, automating it, and driving it towards applications. Together with an industrial partner, we aim to create a user- friendly, prototype instrument in the next three years.


What is your proudest moment in photonics so far? Seeing our work on the cover of Nature Photonics last year was a very special moment – it combined the science of light and the art of light, while blending my professional and family lives. I am really proud of the work our team did in demonstrating third-harmonic chiroptical scattering effects and of course having it featured on the cover of the magazine is an important recognition. But what makes this cover special for me is that we used night photography techniques that I learned on an art course. And I feel really proud that my son built a Lego robot that ran on the optical table while rotating LEDs, tracing beautiful light trails, with the camera in long exposure mode.


Where can people find you online? www.valev.org; @VKValev on Twitter.


Where can people see you in person over the next year? My current plans include: IEEE RAPID; SPIE Photonics West; CLEO Europe.


2024 Photonics100 51


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