Nanophotonics is a field poised to revolutionize the manner in which we interact with light. Everything from smart sensors to holographic screens fall under the purview of this discipline, and advances continue to come thick-and-fast as researchers pin down the properties of light operating at the nanoscale.
Dr Arseniy Kuznetsov, Principal Scientist and head of the Advanced Optical Technologies department at Singapore’s Agency for Science, Technology and Research’s (A*STAR) Institute of Materials Research and Engineering (IMRE), is a decorated researcher whose pioneering work has garnered him a multitude of awards. The NWA spoke with Dr. Kuznetsov, who also sits on the NWA's board of advisors, about his research, and the direction that this field is taking.
Nanophotonics uses nanoantennas to control the phase of light. “The interesting thing is that at nanoscale dimensions light behaves very differently than at conventional large scales. Optics also become very different, so instead of using lenses or mirrors at the nanoscales we need to use nanoantennas.” This is due to the wavelength of light being larger than the nanostructures used. It’s Dr. Kuznetsov’s development of such nanoantennas which has precipitated his success.
Currently nanophotonics is a largely research-based field, with few actualized applications. The concepts are beginning to be applied to biosensors, but there remains a large gap between research and industry. This is because the nanoantennas used have traditionally been made out of plasmonic metals like gold and silver, which have high losses and are incompatible with many nanofabrication processes. Dr. Kuznetsov “realized it was possible to use high-refractive index dielectric or semiconductor structures, which can achieve the same or better properties as plasmonic (metallic) nanoantennas do,” thereby opening the field for further industrial applications.
The most enticing promise of this field is holographic displays, which can project interactive 3D images. Presently the pixel size on such displays is too large and unwieldy for use, resulting in low resolution and low field of view, but “that’s where nanoantennas and the nanophotonics can come in and enable the next generation of these kind of holographic displays.” In order to actualize holographic displays nanoantennas must also be made tuneable, as currently nanoantennas have fixed functions, resulting in a static image.
Another future application is flat optics, which is a manner of manipulating light without the use of bulky lenses. Flat optical elements rely on an array of nanoantennas to focus or change the polarization or phase of light, and can be easily manufactured using semiconductor tools. While this technology is less sensational than holographic displays, the compactness and increased efficiency offered by flat optics has stimulated interest in industries which require more compact and cheap optical devices. Dr. Kuznetsov is currently looking at expanding the applications for existing flat optic technologies.
The final future application that Dr. Kuznetsov lists is LIDAR. “LIDAR is like RADAR, but with light, and is used by autonomous vehicles to scan and map three dimensional surroundings. This will be the key technology to enable autonomous vehicles.” Nanophotonics will enable this technology by allowing large angular scanning and solid-state LIDAR. However, LIDAR will also require tuneable nanoantennas prior to industrial uptake.
In all cases for these applications the principles for developing them are understood by scientists, and it’s a matter of honing the process to produce commercially viable industrial processes. The issue of tuning nanoantennas is particularly prescient, as engineering tuned nanodevices requires advances in nanophotonics, circuitry and tunable materials for the development of tunability at the single-nanoantenna level. “We need to have enough tuning to control the light fully,” which is a sizeable ask.
During the early stages of nanophotonics’ development there was skepticism as to whether the technology would ever be industrially applicable. Initially nanoantennas were produced “using focused ion beam lithography or electron beam lithography, which is not used in industry.” However, “with the transition to dielectric nanoantenna approach, we are starting to use industry grade photolithography tools.” Foundries are now developing services that will allow production of nanophotonic components.
Dr. Kuznetsov emphasizes the importance of integrating research and industry. “I think the key thing now, especially in the field of flat optics, is for researchers to seek real problem statements from industry that they can address using nanophotonic concepts and at the same time industry must propose these problem statements.” Industries, which are not content with the size and weight of optical components, are already working to provide such statements to researchers.
Having done much of his work through the Agency for Science, Technology and Research (A*STAR), Singapore’s lead public sector R&D agency that bridges the gap between academia and industry , Dr. Kuznetsov is approbratory of the organization’s efforts. He works in research management, directing a highly-trained contingent of scientists. “What’s important is to not only produce science and research, but to bring them up to technology level and then commercialization,” he says.
Having conducted and led various research efforts, Dr. Kuznetsov is pleased with the scope of his work “when you have a research team you have many more opportunities to achieve outcomes, and you can combine multiple expertises together and target bigger goals.” Having achieved many of these goals, Dr. Kuznetsov has received a multitude of awards for his work including the prestigious IET Harvey Engineering prize. In 2020, he was also elected to be a Fellow of the Optical Society of America.
By Jack Seaberry