Topologically structured light detects the position of nanomaterials with atomic resolution

Optical imaging and metrology techniques are important tools for research rooted in biology, medicine and nanotechnology. Although these techniques have recently become increasingly advanced, the resolutions they achieve are still significantly lower than those achieved by methods using focused beams of electrons, such as atomic-scale transmission electron spectroscopy and cryo-electron tomography.

Researchers from the University of Southampton and Nanyang Technological University have recently introduced a non-invasive approach to optical measurements with atomic-scale resolution. Their proposed approach is outlined Natural productsIt can open up exciting new possibilities for research in many different fields, allowing scientists to characterize systems or phenomena at the scale of a billionth of a meter.

„Since the nineteenth century, improvements in the spatial resolution of microscopy have been a major trend in science, marked by at least seven Nobel Prizes,” Nikolay I. Zheludev, one of the researchers who conducted the study, told Phys.org. „Our dream was to develop the technology to detect atomic-scale events with light, and we’ve been doing this for the past three years.”

In their experiments, Zeludev and his colleagues demonstrated atomic-scale measurement by collecting single-shot images of the diffraction pattern of topologically structured light with wavelength λ = 488 nm scattered on a 17-μm-long and 200-nm suspended nanowire. -Width, to determine its position relative to the model’s fixed edges.

The researchers trained a deep learning algorithm on a dataset of single-shot images of the scattering patterns that occurred when the nanowire 301 was placed in different positions. After training, the algorithm can predict the positions of a given nanowire based on the scattered light pattern recorded by the panel’s sensor.

„The main idea behind our approach is that complex light is structured at a very fine scale, super-oscillatory light with singularities,” Zheludev explained. „If a sub-wavelength object moves in such a field, the scattering pattern of light on the object is very sensitive to the object’s shape and position. We use a form of artificial intelligence, deep learning analysis of the scattered light’s intensity profile to reconstruct the object’s position.”

In the team’s proof-of-principle experiments, their optical localization metrology method performed remarkably well, resolving the position of a suspended nanowire with subatomic accuracy of 92 pm (i.e., about λ/5,300), while the nanowire naturally oscillates thermally. 150 pm. For reference, the diameter of a silicon atom is 220 pm.

„Our most important achievement was achieving atomic-level resolution in detecting the position of nanomaterials with light,” Zheludev said. „We have achieved resolution thousands of times better than conventional microscopes can provide. Our work opens up the field of picophotonics, the science of light-matter interactions at the picometer scale.”

In their recent study, Zheludev and his colleagues demonstrated the ability to use optical metrology with topologically structured light to collect measurements at an atomic scale. In the future, the approach introduced in their paper could be used by other research groups around the world to study subtle phenomena in greater detail and in non-invasive ways using light.

„We are now working on detecting picometer motions with a high frame rate, so we can film a video that contains the true dynamics of the Brownian motion of a nanoscale object,” Zheludev added.