El Halawany Ahmed, He Sha, Hodaei Hossein, Bakry Ahmed, Razvi Mir A N, Alshahrie Ahmed, Johnson Noah J J, Christodoulides Demetrios N, Almutairi Adah, Khajavikhan Mercedeh
Opt Express. 2016 Jun 27;24(13):13999-4009. doi: 10.1364/OE.24.013999.
Upconversion of near infrared (NIR) into ultraviolet (UV) radiation could lead to a number of applications in bio-imaging, diagnostics and drug delivery. However, for bare nanoparticles, the conversion efficiency is extremely low. In this work, we experimentally demonstrate strongly enhanced upconversion emission from an ensemble of β-NaYF:Gd/Yb/Tm @NaLuF core-shell nanoparticles trapped in judiciously designed plasmonic nanocavities. In doing so, different metal platforms and nanostructures are systematically investigated. Our results indicate that using a cross-shape silver nanocavity, a record high enhancement of 170-fold can be obtained in the UV band centered at a wavelength of 345 nm. The observed upconversion efficiency improvement may be attributed to the increased absorption at NIR, the tailored photonic local density of states, and the light out-coupling characteristics of the cavity.
将近红外（NIR）光上转换为紫外（UV）辐射可在生物成像、诊断和药物递送等领域带来诸多应用。然而，对于裸纳米颗粒而言，其转换效率极低。在本研究中，我们通过实验证明，被捕获在精心设计的等离子体纳米腔中的β-NaYF:Gd/Yb/Tm@NaLuF核壳纳米颗粒集合体的上转换发射得到了显著增强。在此过程中，我们系统地研究了不同的金属平台和纳米结构。我们的结果表明，使用十字形银纳米腔，在以345nm波长为中心的紫外波段可实现高达170倍的创纪录增强。观察到的上转换效率提高可能归因于近红外吸收的增加、定制的光子局域态密度以及腔的光输出耦合特性。
