Abstract

Based on the impedance-matching theory, a double-layer metal structure dynamical focusing cylindrical metalens with a stretchable substrate was designed at the operation frequency of 0.1 THz. The diameter, initial focal length, and NA of the metalens were 80 mm, 40 mm, and 0.7, respectively. The transmission phase of the unit cell structures could cover ${{0 - 2}}\pi$ by changing the size of the metal bars, and then the different unit cells were spatially arranged as the designed phase profile for the metalens. When the stretching range of the substrate was about 100%–140%, the focal length changed from 39.3 mm to 85.5 mm, the dynamic focusing range was about 117.6% of the minimum focal length, and the focusing efficiency decreases from 49.2% to 27.9%. Then, by rearranging the unit cell structures, a dynamically adjustable bifocal metalens was numerically realized. Using the same stretching ratio, compared to a single focus metalens, the bifocal metalens can provide a larger focal length control range.

© 2023 Optica Publishing Group

Multifunctional tunable visible light metalens based on double-layer barium titanate

Shuyuan Lv, Rong Wang, Wenfeng Luo, Yuchi Bai, and Fei Meng
Appl. Opt. 61(17) 5121-5127 (2022)

Graphene aperture-based metalens for dynamic focusing of terahertz waves

Pei Ding, Yan Li, Li Shao, Ximin Tian, Junqiao Wang, and Chunzhen Fan
Opt. Express 26(21) 28038-28050 (2018)

Graphene metalens with dynamic focusing and plane focusing in the terahertz range

Junjie He, Runkai Chen, Yifan Li, Songpei Chen, Zhongmin Liu, and Qingmao Zhang
Appl. Opt. 60(20) 5752-5758 (2021)

Enhancing THz fingerprint detection by the stretchable substrate with a dielectric metagrating

Xiangjun Li, Lu Nie, Hang Wu, Le Zhang, and Dexian Yan
Appl. Opt. 62(34) 9028-9035 (2023)

Focal length switchable metalens based on vanadium dioxide

Junhao Niu, Renfang Tian, Wei Mo, Chunhui Li, Qianyu Yao, and Aijun Zhu
Appl. Opt. 63(9) 2148-2155 (2024)