Extreme Ultraviolet Metalens by Vacuum Guiding
Researchers from Harvard University and Technische Universität Graz have successfully demonstrated the use of metasurfaces as a superior way to focus extreme ultraviolet (EUV) light. The paper titled “Extreme Ultraviolet Metalens by Vacuum Guiding” published in the journal Science Advances, highlights the use of holes in a silicon membrane to efficiently vacuum-guide light around the 50-nm wavelength.
The research team fabricated an EUV metalens with 10-mm focal length supporting numerical apertures of up to 0.05 and used it to focus ultrashort EUV light bursts generated via high-harmonic generation down to a 0.7-µm waist. This approach introduces the vast light-shaping possibilities provided by dielectric metasurfaces to a spectral regime lacking materials for transmissive optics.
The greateyes detector (GE 1024 256 BIUV1), optimized for EUV wavelengths, was an integral part of the experimental setup which the research team operates at the TU Graz. The camera is very compact and has a sensor optimized for the highest sensitivity in the EUV spectral range.
Dielectric metasurfaces consist of transparent nanostructures with subwavelength separation, which manipulate the phase of light on the nanoscale. This elaborate control is revolutionizing modern optics and can replace bulky optics by thin and flat elements to combine multiple functions in single optical elements.
This breakthrough in EUV light focusing has significant implications for material science, attosecond metrology, and lithography. The technology can be used to design novel optical elements for ever-shorter wavelength radiation, which has been stalled at ultraviolet frequencies where dielectrics stop being transparent. The researchers hope that their approach will pave the way for further research in the field of EUV light focusing and lead to the development of new technologies that can benefit various industries.
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