Measuring Nano-Structured Light Fields

A monolayer of organic molecules is placed in the focused light field and replies to this illumination by fluorescence, embedding all information about the invisible properties (Source: P. Runde, U. Muenster)

Structured laser light has already opened up various different applications: It allows for precise material machining, trapping, manipulating or defined movement of small particles or cell compartments, as well as increasing the bandwidth for next-generation intelligent computing.

If these light structures are tightly focused by a lens, highly intense three-dimensional light landscapes will be shaped, facilitating a significantly enhanced resolution in named applications. These kinds of light landscapes have paved the way to pioneering applications as Nobel Prize-awarded STED microscopy.

However, these nano fields themselves could not be measured yet, since components are formed by tight focusing and thus invisible for typical measurement techniques. Up to now, this lack of appropriate metrological methods has impeded the breakthrough of nano-structured light landscapes as a tool for material machining, optical tweezers, or high-resolution imaging.

A team around physicist Cornelia Denz of the Institute of Applied Physics and chemist Bart Jan Ravoo of the Center for Soft Nanoscience at the University of Muenster, Germany, successfully developed a nano-tomographic technique which is able to detect the typically invisible properties of nano-structured fields in the focus of a lens – without requiring any complex analysis algorithms or data post-processing.

For this purpose, the team combined their knowledge in the field of nano-optics and organic chemistry to realize an approach based on a monolayer of organic molecules. This monolayer is placed in the focused light field and replies to this illumination by fluorescence, embedding all information about the invisible properties.

By the detection of this reply, the distinct identification of the nano field by a single, fast and straightforward camera image is enabled. “This approach finally opens the until-now unexploited potential of these nano-structured light landscapes for many more applications,” says Denz. (Source: U. Muenster)

Reference: E. Otte et al.: Polarization nano-tomography of tightly focused light landscapes by self-assembled monolayers, Nat. Comm. 10, 4308 (2019); DOI: 10.1038/s41467-019-12127-3

Links: Nonlinear Photonics group (C. Denz), Institut für Angewandte Physik, Universität Münster, GermanyFOKUS-Professorship for Synthesis of Nanoscale Systems (B. J. Ravoo), Organisch-Chemisches Institut, Universität Münster, Germany

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