Continuously varifocal metalens for broadband achromatic focusing of terahertz waves

• DOI: 10.1016/j.jsamd.2023.100560
• Publication Date: 2023-04-11T16:23:57Z
• Authors: Xiao-Qiang Jiang; Wen-Hui Fan; Lv-Rong Zhao; Xu Chen; Chong Qin; Hui Yan; Qi Wu; Pei Ju
• Keywords: Achromatic lens; Chromatic aberration; Numerical aperture; Aperture (computer memory)

The correction of chromatic aberration is essential for promoting broadband imaging systems, which can be accomplished by recently proposed achromatic metalenses (BAMs) in a more compact and efficient way compared to that traditional optical lenses. However, current BAMs are limited the fixed functionality severely hinders their potential applications. In order address such limitation, continuously varifocal metalens (CVBAM) converging THz waves employing thermally tunable material indium antimonide. At initial temperature, numerical results manifest over 1.8–2.2 well corrected CVBAM transverse sizes corresponding focal spots beyond Abbe diffraction limit. Moreover, aperture (NA) average focusing efficiency up 0.62 73.3%, respectively. addition, length has range from 736.25 μm (NA = 0.62) 861.02 0.56) altering operation temperature. This work may offer an advanced scheme designing BAMs, remarkably facilitate development near-field spectroscopy systems.