Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, People’s Republic of China.
Nanotechnology. 2012 Jul 11;23(27):275501. doi: 10.1088/0957-4484/23/27/275501. Epub 2012 Jun 18.
We study numerically and analytically the refractive index sensing sensitivities of surface plasmon (S(SP)) and waveguide (S(WG)) modes arising from one-dimensional Au gratings. By using rigorous coupled wave analysis, we find that while S(SP) is mainly controlled by the periodicity of the grating, the shape of the groove governs S(WG). As a result, it is possible to increase S(WG) to 1000 nm/RIU and figure of merit to 24 by tailoring the height and width of the groove. Finally, a simple analytical expression is derived to describe S(WG) and it agrees well with the numerical data. This easy-to-use expression not only reveals the origin of waveguide mode sensitivity, but also provides useful guidance for the theoretical design and experimental realization of high-sensitivity metallic-gratings-based biosensors.
我们通过数值和解析方法研究了一维金光栅产生的表面等离子体（S(SP)）和波导（S(WG)）模式的折射率传感灵敏度。通过严格耦合波分析，我们发现 S(SP)主要由光栅的周期性控制，而槽的形状则控制 S(WG)。因此，通过调整槽的高度和宽度，可以将 S(WG)增加到 1000nm/RIU，品质因数增加到 24。最后，推导出了一个简单的解析表达式来描述 S(WG)，并且与数值数据吻合得很好。这个易于使用的表达式不仅揭示了波导模式灵敏度的起源，而且为基于金属光栅的高灵敏度生物传感器的理论设计和实验实现提供了有用的指导。
