Kanwal Saima, Wen Jing, Yu Binbin, Kumar Dileep, Chen Xu, Kang Yi, Bai Chunyan, Zhang Dawei
Engineering Research Center of Optical Instrument and Systems, Ministry of Education and Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, No. 516 Jun Gong Road, Shanghai 200093, China.
State Key Laboratory of Industrial Control Technology, College of Control Science and Engineering, Zhejiang University, Hangzhou 310027, China.
Nanomaterials (Basel). 2020 Mar 9;10(3):490. doi: 10.3390/nano10030490.
Ultraviolet (UV) optical devices have plenteous applications in the fields of nanofabrication, military, medical, sterilization, and others. Traditional optical components utilize gradual phase accumulation phenomena to alter the wave-front of the light, making them bulky, expensive, and inefficient. A dielectric metasurface could provide an auspicious approach to precisely control the amplitude, phase, and polarization of the incident light by abrupt, discrete phase changing with high efficiency due to low absorption losses. Metalenses, being one of the most attainable applications of metasurfaces, can extremely reduce the size and complexity of the optical systems. We present the design of a high-efficiency transmissive UV metalens operating in a broadband range of UV light (250-400 nm) with outstanding focusing characteristics. The polarization conversion efficiency of the nano-rod unit and the focusing efficiency of the metasurface are optimized to be as high as 96% and 77%, respectively. The off-axis focusing characteristics at different incident angles are also investigated. The designed metalens that is composed of silicon nitride nanorods will significantly uphold the advancement of UV photonic devices and can provide opportunities for the miniaturization and integration of the UV nanophotonics and its applications.
紫外（UV）光学器件在纳米制造、军事、医疗、灭菌等领域有大量应用。传统光学元件利用相位逐渐累积现象来改变光的波前，这使得它们体积庞大、成本高昂且效率低下。介电超表面可以提供一种良好的方法，通过由于低吸收损耗而实现的高效、突然的离散相变来精确控制入射光的幅度、相位和偏振。金属透镜作为超表面最可行的应用之一，可以极大地减小光学系统的尺寸和复杂性。我们展示了一种在宽波段紫外光（250 - 400 nm）范围内工作且具有出色聚焦特性的高效透射式紫外金属透镜的设计。纳米棒单元的偏振转换效率和超表面的聚焦效率分别优化至高达96%和77%。还研究了不同入射角下的离轴聚焦特性。由氮化硅纳米棒组成的所设计金属透镜将显著推动紫外光子器件的发展，并可为紫外纳米光子学及其应用的小型化和集成提供机遇。
