Shi Yilin, Dai Hao, Tang Renjie, Chen Zequn, Si Yalan, Ma Hui, Wei Maoliang, Luo Ye, Li Xingyi, Zhao Qing, Ye Yuting, Jian Jialing, Sun Chunlei, Bao Kangjian, Ma Yaoguang, Lin Hongtao, Li Lan
State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Micro-Nano Electronics and Smart System of Zhejiang Province College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China.
Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province, School of Engineering, Westlake University, Hangzhou 310030, China.
Nanophotonics. 2023 Nov 17;13(8):1339-1349. doi: 10.1515/nanoph-2023-0561. eCollection 2024 Apr.
The ever-growing demand for miniaturized optical systems presents a significant challenge in revolutionizing their core element - the varifocal lens. Recent advancements in ultra-thin, tunable metasurface optics have introduced new approaches to achieving zoom imaging. However, current varifocal metalens have faced challenges such as low focusing efficiency, limited tunability, and complicated designs. Here, we employ the high-contrast transmit arrays (HCTA) structures to design and fabricate a polarization-independent, single-layer flexible metalens that operates at a wavelength of 940 nm. Using a uniform stretching system, we characterized its optical performance to achieve over 60 % focusing efficiency within a 0 %-25 % stretch range, while the focal length changes align with theoretical predictions. Furthermore, our research also successfully demonstrated the capacity of a metalens with a numerical aperture (NA) of 0.5 to efficiently adjust imaging magnification within a 2× range, achieving imaging results that approach the diffraction limit. This research offers promising prospects for the practical use of compact and miniaturized optoelectronic devices in fields like photography, mixed reality, microscopy, and biomedical imaging.
对小型化光学系统不断增长的需求，给其核心元件——变焦透镜的革新带来了重大挑战。超薄、可调谐超表面光学的最新进展，为实现变焦成像引入了新方法。然而，当前的变焦超透镜面临着诸如聚焦效率低、可调性有限和设计复杂等挑战。在此，我们采用高对比度透射阵列（HCTA）结构来设计和制造一种在940纳米波长下工作的偏振无关单层柔性超透镜。利用均匀拉伸系统，我们对其光学性能进行了表征，在0%-25%的拉伸范围内实现了超过60%的聚焦效率，同时焦距变化与理论预测相符。此外，我们的研究还成功证明了数值孔径（NA）为0.5的超透镜在2倍范围内有效调整成像放大率的能力，成像结果接近衍射极限。这项研究为紧凑型和小型化光电器件在摄影、混合现实、显微镜和生物医学成像等领域的实际应用提供了广阔前景。
