Pan Zhiwen, Wondraczek Lothar
Otto Schott Institute of Materials Research, University of Jena, Fraunhoferstrasse 6, 07743, Jena, Germany.
Sci Rep. 2018 Jun 22;8(1):9527. doi: 10.1038/s41598-018-27916-x.
Dedicated control of axial light emission from light-guides enables a new generation of functional light sources for volumetric illumination. A primary challenge is to ensure homogeneous emission intensity across the full length of the device. Here, we introduce an approach towards homogeneously side-emitting waveguides which do not rely on imposing local scattering centers such as bubbles, micro-/nanoparticles, and rough or abrupt interfaces, but on modulated core radius. Previous quantitative studies of the relationship between structural parameters and radiation losses provide initial conditions for tailoring side-emission through core-diameter modulations, however, with strongly limited amplitude of modulation. We now employ and verify numerical simulation to overcome this limitation towards meter-long homogeneously side-emitting waveguides in which the amplitude of core-diameter modulation is of the same order of magnitude as the core diameter itself. Similar emission properties can be obtained through modulation of the core refractive index instead of the core diameter, or through a combination of both approaches. Using the present model, we deduce exemplary conditions for homogeneous side-emission in which the power flow within the waveguides decays linearly, what may present another interesting feature for applications beyond illumination.
对光导轴向光发射的专门控制能够实现新一代用于体照明的功能性光源。一个主要挑战是要确保在整个器件长度上发射强度均匀。在此，我们介绍一种实现均匀侧向发光波导的方法，该方法不依赖于施加诸如气泡、微/纳米颗粒以及粗糙或突变界面等局部散射中心，而是基于调制芯半径。先前对结构参数与辐射损耗之间关系的定量研究为通过芯径调制来定制侧向发射提供了初始条件，然而，调制幅度受到很大限制。我们现在采用并验证数值模拟来克服这一限制，以实现米级均匀侧向发光波导，其中芯径调制幅度与芯径本身处于同一数量级。通过调制芯折射率而非芯径，或者通过两种方法的组合，也可以获得类似的发射特性。利用当前模型，我们推导出均匀侧向发射的示例性条件，其中波导内的功率流呈线性衰减，这对于照明以外的应用可能呈现出另一个有趣的特性。
