Kasztelanic Rafal, Filipkowski Adam, Anuszkiewicz Alicja, Stafiej Paulina, Stepniewski Grzegorz, Pysz Dariusz, Krzyzak Konrad, Stepien Ryszard, Klimczak Mariusz, Buczynski Ryszard
Department of Glass, Institute of Electronic Materials Technology, Wolczynska 133, 01-919, Warsaw, Poland.
Faculty of Physics, University of Warsaw, Pasteura 7, 02-093, Warsaw, Poland.
Sci Rep. 2018 Mar 22;8(1):5072. doi: 10.1038/s41598-018-23464-6.
We present both a theoretical and an experimental study of a novel compact lensed fiber system utilizing a nanostructured GRIN lens. The lens can be integrated with an optical fiber, which ensures a unique and efficient focusing in any high index medium, such as a liquid. We use the effective medium approach to design lenses with arbitrary refractive index. To fabricate lenses, we utilize a discrete array of nano-sized rods made of two types of glasses, and apply a standard stack-and-draw fiber drawing technology. The fabricated nanostructured GRIN lenses have a parabolic refractive index profile with a diameter of a standard fiber, very short working distances (55 µm in the air) and a high numerical aperture (NA = 0.16). As a proof-of-concept of the new micro-lensed fiber system, we demonstrate an experiment on optical trapping of micrometer-sized glass beads. We also show that our method is compatible with optical fiber technology and allows for any shape of the refractive index distribution in 2D. Thanks to that a new functionality could be achieved by replacing the GRIN lens with an axicon lens, vortex type elements, micro-lenses arrays or diffraction elements.
我们展示了一项关于利用纳米结构渐变折射率（GRIN）透镜的新型紧凑型透镜光纤系统的理论和实验研究。该透镜可与光纤集成，这确保了在任何高折射率介质（如液体）中实现独特且高效的聚焦。我们使用有效介质方法来设计具有任意折射率的透镜。为了制造透镜，我们利用由两种类型玻璃制成的纳米尺寸棒的离散阵列，并应用标准的堆叠拉拔光纤拉丝技术。所制造的纳米结构GRIN透镜具有与标准光纤直径相同的抛物线折射率分布、非常短的工作距离（在空气中为55 µm）和高数值孔径（NA = 0.16）。作为新型微透镜光纤系统概念验证，我们展示了对微米级玻璃珠进行光镊操作的实验。我们还表明，我们的方法与光纤技术兼容，并允许二维中任意形状的折射率分布。得益于这一点，通过用轴棱锥透镜、涡旋型元件、微透镜阵列或衍射元件替换GRIN透镜，可以实现新的功能。
