Optical resonances in microcylinders: response to perturbations for biosensing
Optical resonances in microcylinders: response to perturbations for biosensing
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DOI：
10.1364/josab.25.001312
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发表时间：
2008-08-01
影响因子：
1.9
通讯作者：
Langbein, W.
中科院分区：
文献类型：
--
作者：
Chantada, L.;Nikolaev, N. I.;Langbein, W.
对介质微柱中的回音壁模式进行了数值研究，作为环境介质的敏感探针，用于化学传感和生物传感。我们考虑的几何形状，WGM退出通过挫折全内反射前平面介质基板，在最近的实验报告。基片和圆柱体之间的光耦合产生WGM展宽，WGM展宽随着圆柱体和基片之间距离的增加而指数减小。我们还考虑了衬底和圆柱体之间的分离层，其导致WGM加宽和偏移，这取决于层和周围介质之间的折射率失配，并且发现对于几个百分之一范围内的失配，Q值> 10（5）是可能的。对于生物传感应用，我们计算了单个和多个不同大小的圆柱形颗粒附着到圆柱表面以模拟生物分析物的效果。我们发现，不仅WGM位移，但也加宽和分裂作为不同属性的分析物的敏感指标。特别地，在单个颗粒的情况下，可以从WGM偏移和加宽确定颗粒尺寸和折射率，从而打开了适用于单个对象（例如病毒或细菌）的生物传感的新模式的视角。在多粒子的情况下，结果进行统计分析，在其表面覆盖。(C)2008年美国光学学会。
Whispering gallery modes (WGMs) in dielectric microcylinders are investigated numerically as sensitive probes of the surrounding medium, for applications in chemical sensing and biosensing. We consider a geometry where WGMs are exited via frustrated total internal reflection front a planar dielectric substrate, as reported in recent experiments. The optical coupling between the substrate and the cylinder yields a WGM broadening exponentially decreasing with increasing distance between the cylinder and the substrate. We also consider a separation layer between the substrate and the cylinder that results in a WGM broadening and shift depending on the index mismatch between the layer and the surrounding medium, and find that Q values > 10(5) are possible for a mismatch in the few pet-cent range. For biosensing applications we calculate the effect of single and multiple cylinder-shaped particles of different sizes attached to the cylinder surface to simulate biological analytes. We find not only WGM shifts but also broadenings and splittings acting as sensitive indicaters of different properties of the analytes. In particular, in the case of a single particle, both particle size and refractive index can be determined from the WGM shift and broadening, opening the perspective to a new modality of biosensing applicable to single objects such as viruses or bacteria. In the multiparticle case, the results are statistically analyzed in terms of their surface coverage. (C) 2008 Optical Society of America.