A Helical Soft-X-ray Beam

Controlling the properties of light is of great importance for many areas of physics, including imaging and nano­lithography. But for short wavelengths, such as soft-X-ray radiation, such control over especially the phase of light has remained elusive. Now, Lars Loet­gering and Stefan Witte from the Advanced Research Center for Nano­lithography, together with colleagues from Germany and the USA, report on a method that enables the generation of soft-X-ray beams with controlled orbital angular momentum (OAM).

A cross-sectional images of a helical soft-X-ray beam. (Source: ARCNL)

OAM is a property of light in which the phase of a light beam rotates around the beam axis. The ARCNL team now demons­trates that, by inserting a specially designed structure into the beam path, the light can be diffracted in such a way that its OAM pro­perties are modified. Being able to control OAM of light is an important first step; it will give researchers access to the angular structure of the soft-X-ray beam.

Loetgering and colleagues used this new method to generate helical beams of soft-X-ray radiation, in which the intensity distri­bution of light rotates around its axis upon propa­gation. They employed a special imaging approach – ptycho­graphy – to characterize the intensity and phase properties of these helical beams in great detail. Furthermore, they demons­trated the potential of these special beams for high-reso­lution micro­scopy, by using them to image a cross-section of an inte­grated circuit at 30 nanometer spatial resolution. (Source: ARCNL)

Reference: L. Loetgering et al.: Generation and characterization of focused helical x-ray beams, Sci. Adv. 6, eaax8836 (2020); DOI: 10.1126/sciadv.aax8836

Link: Advanced Research Center for Nanolithography ARCNL, Amsterdam, Netherlands

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