Effects of photonic structures on upconversion
Effects of photonic structures on upconversion
复制标题
光子结构对上转换的影响
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
J. Goldschmidt
中科院分区：
文献类型：
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作者：
B. Herter;S. Wolf;S. Fischer;M. Peters;B. Bläsi;J. Goldschmidt
光子晶体改变光子态的局部密度。这些变化影响嵌入光子晶体内的偶极子的发射特性。此外，可以在光子晶体内观察到场增强。在本文中，我们研究了这些效应如何影响 β-NaYF4:Er3+ 的上转换过程。为此，我们使用光栅波导结构的时域有限差分 (FDTD) 模拟以及 β-NaYF4:Er3+ 中上转换过程的速率方程模型。光栅参数经过优化，可在结构内实现 s 偏振光和 p 偏振光组合的大场增强。此外，还模拟了结构内偶极子发射体自发发射率的变化。不同的转变速率以及场增强充当上转换速率方程模型的输入参数。使用这种方法，计算了结构对上转换量子产率的影响。对于 1000 W/m2 的模拟初始辐照度，我们发现上变换器区域中的场增强的增强因子高达四倍，上变换量子产率高达三倍。因此，在光子结构中加入上转换材料非常有希望提高上转换效率。
Photonic crystals modify the local density of photon states. These variations influence the emission properties of a dipole embedded within the photonic crystal. Furthermore, field enhancement can be observed within photonic crystals. In this paper, we investigate how these effects influence upconversion processes in β-NaYF4:Er3+. For this purpose we use finite-difference time-domain (FDTD) simulations of a grating-waveguide-structure in combination with a rate equation model of the upconversion processes in β-NaYF4:Er3+. The grating parameters are optimized to achieve large field enhancements within the structure for the combination of s- and p-polarized light. Furthermore, the variation of the spontaneous emission rates for dipole emitters within the structure is simulated. The varied transition rates, as well as the field enhancement, serve as input parameters for the rate equation model for upconversion. Using this approach, the influence of the structure on the upconversion quantum yield is calculated. For a simulated initial irradiance of 1000 W/m2, we find enhancement factors of up to four for the field enhancement in the upconverter region and up to a factor of three for the upconversion quantum yield. In consequence, the incorporation of upconverting material in photonic structures in very promising to increase upconversion efficiencies.