Localized in-line precipitation of metallic nanostructures in hybrid optical fibers

功能性玻璃纤维已经成为各种光学器件中的关键部件，从无源波导，电信和数据传输，到光纤光源、光放大器、传感器、滤波器和开关中的有源功能。然而，几十年来，技术平台一直局限于相对较少的主要纤维结构，特别是化学成分，其中二氧化硅和硅基玻璃仍然是最突出的纤维材料。这在很大程度上是由于制造限制和材料相容性的限制，这阻止了对外来玻璃性质的利用，例如，硫属化物或金属掺杂玻璃的极端光学非线性，具有二氧化硅的加工稳定性和光学性能。这些所谓的混合玻璃纤维如今代表了材料开发和加工的主要挑战之一，因为它们能够将物理性能工程的极限推到目前已知的范围之外。例如，它们将实现数值孔径的极端值，或者，本提案的主题，功能和无源材料架构的极端组合，用于定制的物理特性曲线。将玻璃形成液体（通过压力或表面张力辅助）填充到基于二氧化硅的光子晶体光纤或毛细管装置的微米孔或纳米孔中最近已被引入作为用于制造下一代混合玻璃光纤装置的非常有前途的平台。然而，这种新兴的专用光学玻璃纤维加工方法中的一个长期问题是局部材料特性的定制。另一方面，这种在线结构化，例如介电梯度、光栅、网格或特定等离子体活性的生成，是解决未来设备需求的下一步的先决条件。在这里，目前的关键是要获得专门的理解，这种在线处理，其基本的热动力学和光化学原理，以及其物理限制。因此，本提案的目标是通过外部场对混合光纤中金属纳米结构的局部沉淀的基本理解。我们打算探索控制光纤设备内部颗粒沉淀的基本材料方面，提供有关反应动力学，横向分辨率，光稳定性以及最重要的是这种玻璃纤维的光学活性的限制的机械信息。这将需要新一代的有源光纤器件，其将二氧化硅的光学特性与光敏的、掺杂金属的低熔点玻璃的等离子体活性结合联合收割机。

Functional glass fiber has been the key component in a broad variety of optical devices, ranging from passive waveguiding in, e.g., telecommunication and data transfer, to active functionality in fiber light sources, optical amplifiers, sensors, filters and switches. However, for decades, the technological platform has been limited to a relatively small number of principal fiber architectures and, in particular, chemical compositions, where silica and silica-based glasses are still the most prominent fiber material. This has largely been due to fabrication limits and limits of material compatibility, which prevented exploitation of exotic glass properties such as, e.g., the extreme optical nonlinearity of chalcogenides or metal-doped glasses, with the processing stability and optical performance of silica. These so-called hybrid glass fibers today represent one of the major challenges for materials development and processing, as they enable pushing the limits of physical property engineering to beyond what is presently known. For example, they would enable extreme values of numerical aperture or, subject of the present proposal, extreme combinations of functional and passive material architectures for tailored profiles of physical properties. Filling glass-forming liquids (assisted through pressure or surface tension) into the micro- or nanobores of silica-based photonic crystal fiber or capillary devices has recently been introduced as a highly promising platform for fabricating the next generation of hybrid glass fiber devices. A standing issue in this emerging approach to dedicated optical glass fiber processing is, however, the tailoring of local materials properties. Such in line structuring, for example, the generation of dielectric gradients, optical gratings, grids or specific plasmonic activity, on the other side, is the prerequisite for the next step towards solving future device needs. Here, the present key is to obtain a dedicated understanding of such in line processing, its underlying thermokinetic and photochemical principles, and its physical limits. The present proposal therefore targets a fundamental understanding of the local precipitation of metallic nanostructures in hybrid optical fibers through external fields. We intend to explore the basic materials aspects which control particle precipitation inside an optical fiber device, providing mechanistic information on limits of reaction kinetics, lateral resolution, photostability and, most importantly, optical activity of such glass fiber. This shall need to a new generation of active fiber devices which combine the optical properties of silica with the plasmonic activity of photosensitive, metal-doped low-melting glasses.