穴を使って真空ガイドを作るナノ加工技術で、光学の壁を破る Nanofabrication technique, using holes to create vacuum guides, breaks a barrier in optics
2023-04-06 ハーバード大学
EUVレンズは、非常に小さな波長を持つため、従来の光学デバイスでは制御することができなかった。しかしながら、ハーバード大学の研究者たちは、空気の中の真空を利用することで、ナノサイズの穴からEUV光を誘導し、制御することができるメタレンズを製作することに成功しました。
これにより、EUVの高性能・大量応用に有用なレンズが開発され、EUレンズ技術は、ナノ技術において、世界中の産業に革命をもたらすことが期待されます。
＜関連情報＞
- https://seas.harvard.edu/news/2023/04/first-its-kind-metalens-can-focus-extreme-ultraviolet-light
- https://www.science.org/doi/10.1126/science.adg6881
真空誘導による極端紫外メタレンズ Extreme ultraviolet metalens by vacuum guiding
Marcus Ossiander,Maryna Leonidivna Meretska ,Hana Kristin Hampel,Soon Wei Daniel Lim ,Nico Knefz ,Thomas Jauk,Federico Capasso and Martin Schultze
Science Published:6 Apr 2023
DOI:https://doi.org/10.1126/science.adg6881
Pushing metalenses to extremes
The fields of ultrafast spectroscopy and semiconductor photolithography rely on very short wavelengths, typically in the extreme ultraviolet (EUV) realm. However, most optical materials strongly absorb light in this wavelength regime, resulting in a lack of generally available transmissive components. Ossiander et al. designed and fabricated a metalens in which a carefully engineered array of holes in a thin silicon membrane focuses ultrafast EUV pulses close to the diffraction limit by “vacuum guiding.” The results open up transmissive optics to the EUV regime. —ISO
Abstract
Extreme ultraviolet (EUV) radiation is a key technology for material science, attosecond metrology, and lithography. Here, we experimentally demonstrate metasurfaces as a superior way to focus EUV light. These devices exploit the fact that holes in a silicon membrane have a considerably larger refractive index than the surrounding material and efficiently vacuum-guide light with a wavelength of ~50 nanometers. This allows the transmission phase at the nanoscale to be controlled by the hole diameter. We fabricated an EUV metalens with a 10-millimeter focal length that supports numerical apertures of up to 0.05 and used it to focus ultrashort EUV light bursts generated by high-harmonic generation down to a 0.7-micrometer waist. Our approach introduces the vast light-shaping possibilities provided by dielectric metasurfaces to a spectral regime that lacks materials for transmissive optics.
