Extreme-ultraviolet refractive optics

TL;DR

This paper demonstrates the control of extreme-ultraviolet (XUV) light refraction using a gas jet with a density gradient, enabling new optical components like lenses and prisms in the XUV spectral region.

Contribution

It introduces a gas-phase prism and a deformable XUV refractive lens, overcoming absorption issues and enabling tunable focusing in the XUV range, a significant advancement in optical technology.

Findings

Gas jet with density gradient causes frequency-dependent XUV beam deflection.

A gas phase prism achieves controlled XUV beam deflection near atomic resonances.

Deformable XUV lens with tunable focal length demonstrated.

Abstract

Refraction is a well-known optical phenomenon that alters the direction of light waves propagating through matter. Microscopes, lenses and prisms based on refraction are indispensable tools for controlling the properties of light beams at visible, infrared, ultraviolet and X-ray wavelengths. The large absorption of extreme-ultraviolet (XUV) radiation in matter, however, hinders the development of refractive lenses and prisms in this spectral region. Here, we demonstrate control over the refraction of XUV radiation by using a gas jet with a density gradient across the XUV beam profile. A gas phase prism is demonstrated that leads to a frequency-dependent deflection of the XUV beam. The strong deflection in the vicinity of atomic resonances is further used to develop a deformable XUV refractive lens, with low absorption and a focal length that can be tuned by varying the gas pressure. Our results provide novel opportunities in XUV science and open a route towards the transfer of refraction-based techniques including microscopy and nanofocusing, which are well established in other spectral regions, to the XUV domain.