High-Efficiency Reflective Focusing in Extreme Ultraviolet with Multilayer Metalens

Abstract

The focusing of extreme ultraviolet light is essential for high-precision lithography, high-resolution imaging, and fine measurement. The investigation of extreme ultraviolet metalens presents significant opportunities for advancing metaoptics. However, the transmissive extreme ultraviolet metalens suffers from low efficiency due to high-order diffraction. Here, we propose a high-efficiency extreme ultraviolet reflective metalens composed of multilayer films and vacuum holes. By means of meticulous design and structural optimization, the reflective configurations based on multilayer films support a complete 2π phase profile in a small period with high-efficiency meta-atoms. The extreme ultraviolet reflective metalens with a numerical aperture of 0.05 achieves a high-quality focusing profile with a relative focusing efficiency of 65.77% and an absolute focusing efficiency of 15.80%. Comparisons with other works highlight the superiority of our design. The absolute focusing efficiency of the proposed extreme ultraviolet reflective metalens is twice that of previously reported works, demonstrating that high-order diffraction can be effectively suppressed not only by reducing the period but also by incorporating multilayer films. This work demonstrates a high-efficiency extreme ultraviolet reflective metalens and elucidates its underlying physical mechanism, paving the way for advanced extreme ultraviolet light manipulation.

Keywords: EUV metalens, Multilayer films, Diffraction suppression