Zheng Xiaorui, Jia Baohua, Lin Han, Qiu Ling, Li Dan, Gu Min
Centre for Micro-Photonics in Faculty of Science, Engineering and Technology at Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122, Australia.
Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800, Australia.
Nat Commun. 2015 Sep 22;6:8433. doi: 10.1038/ncomms9433.
Nanometric flat lenses with three-dimensional subwavelength focusing are indispensable in miniaturized optical systems. However, they are fundamentally challenging to achieve because of the difficulties in accurately controlling the optical wavefront by a film with nanometric thickness. Based on the unique and giant refractive index and absorption modulations of the sprayable graphene oxide thin film during its laser reduction process, we demonstrate a graphene oxide ultrathin (∼200 nm) flat lens that shows far-field three-dimensional subwavelength focusing (λ(3)/5) with an absolute focusing efficiency of >32% for a broad wavelength range from 400 to 1,500 nm. Our flexible graphene oxide lenses are mechanically robust and maintain excellent focusing properties under high stress. The simple and scalable fabrication approach enables wide potential applications in on-chip nanophotonics. The wavefront shaping concept opens up new avenues for easily accessible, highly precise and efficient optical beam manipulations with a flexible and integratable planar graphene oxide ultrathin film.
具有三维亚波长聚焦功能的纳米平面透镜在小型化光学系统中不可或缺。然而，由于难以通过纳米厚度的薄膜精确控制光波前，实现这种透镜具有根本性挑战。基于可喷涂氧化石墨烯薄膜在激光还原过程中独特且巨大的折射率和吸收调制特性，我们展示了一种氧化石墨烯超薄（约200纳米）平面透镜，该透镜在400至1500纳米的宽波长范围内呈现远场三维亚波长聚焦（λ(3)/5），绝对聚焦效率大于32%。我们的柔性氧化石墨烯透镜机械性能稳健，在高应力下仍保持出色的聚焦特性。这种简单且可扩展的制造方法在片上纳米光子学领域具有广泛的潜在应用。波前整形概念为利用柔性且可集成的平面氧化石墨烯超薄薄膜轻松实现、高精度且高效的光束操控开辟了新途径。
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