Elrafei Sara, Kandas Ishac, Shehata Nader, Samir Effat
Opt Express. 2018 Sep 17;26(19):25492-25506. doi: 10.1364/OE.26.025492.
The up-conversion process is extensively studied because of its wide variety of applications such as bioimaging, energy harvesting, and optical sensors. However, the optical conversion efficiency is still relatively low and needs to be improved. Therefore, this paper introduces a detailed study of improving the up-conversion emission efficiency through adding plasmonic metallic nanostructures to the up-conversion optical centers. Our idea is to couple the optical plasmonic resonance with the visible emission of the optical centers under IR excitation. The optical centers are erbium ions hosted by fluoride low-phonon environment. Our calculations consider most possible transitions that can occur between the optical centers; tri-valent erbium ions, through Judd-Ofelt analysis. In addition, the effect of changing some parametric values is discussed, such as irradiance, and multi-phonon relaxations, to show their optimum values which correspond to best quantum yield efficiency. By increasing the diameter of added gold nanoparticles (Au NPs), the probability of occupation has been increased, and consequently, both the luminescence and up-conversion efficiency have been increased.
由于上转换过程在生物成像、能量收集和光学传感器等多种应用中有着广泛的应用，因此对其进行了广泛的研究。然而，光转换效率仍然相对较低，需要提高。因此，本文详细介绍了通过在光转换光学中心添加等离子体金属纳米结构来提高上转换发射效率的研究。我们的想法是在红外激发下，将光学等离子体共振与光学中心的可见光发射耦合起来。光学中心是由氟化物低声子环境承载的铒离子。我们的计算考虑了光学中心之间最可能发生的跃迁；通过Judd-Ofelt分析，研究三价铒离子。此外，还讨论了改变一些参数值（如辐照度和多声子弛豫）的影响，以显示它们对应于最佳量子产率效率的最佳值。通过增加添加的金纳米颗粒（Au NPs）的直径，占据概率增加，因此，发光和上转换效率都得到了提高。
