使用高折射率纳米和近纳米层的波导表面的增强倏逝场光谱
Enhanced Evanescent Field Spectroscopy at Waveguide Surfaces using High Index Nano and Near-Nano Layers
摘要：
我们提出并证明，通过模拟和实验，如何设计用于化学传感的波导内的光场的相互作用，更一般地说，倏逝场光谱可以通过高折射率表面层的战略沉积大大增强。这些层引出探测附近的光场，并通过光学阻抗匹配利用场定位。渐逝场向内层的局部化反过来又伴随着结构化圆柱形波导通道内的回音壁模式，进一步增强灵敏度。一种新的示范的基础上的自组装层由二氧化钛内的结构光纤的演示，使用一个简单的卟啉作为光谱探针。这种技术提供了对实际波导传感器的限制的优化，实际波导传感器是高度敏感的，但几乎总是以低损耗为代价。的原则有潜在的影响纳米光子学更普遍，这些进行了讨论。
英文摘要：
We propose and demonstrate, through simulation and experiment, how the interaction of an optical field within a waveguide designed for chemical sensing and, more generally, evanescent field spectroscopy can be enhanced substantially by strategic deposition of high index surface layers. These layers draw out the optical field in the vicinity of probing and take advantage of field localisation through optical impedance matching. Localisation of the evanescent field to the inner layer in turn is accompanied by whispering gallery modes within the channels of a structured cylindrical waveguide, further enhancing sensitivity. A novel demonstration based on self-assembled layers made up of TiO2 within a structured optical fibre is demonstrated, using a simple porphyrin as the spectroscopic probe. This technique offers optimisation of the limitations imposed on practical waveguide sensors that are highly sensitive but nearly always at the expense of low loss. The principles have potential ramifications for nanophotonics more generally and these are discussed.
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