Kwon Soon-Hong
Department of Physics, Chung-Ang University, Seoul 06974, Korea.
Sensors (Basel). 2017 Nov 3;17(11):2526. doi: 10.3390/s17112526.
Sensitive refractive index sensors with small footprints have been studied to allow the integration of a large number of sensors into a tiny chip for bio/chemical applications. In particular, resonant-type index sensors based on various micro/nanocavities, which use a resonant wavelength dependence on the refractive index of the analyte, have been developed. However, the spectral linewidth of the resonance, which becomes the resolution limit, is considerably large in plasmonic cavities due to the large absorption loss of metals. Therefore, there is demand for a new type of plasmonic refractive index sensor that is not limited by the linewidth of the cavity. We propose a new type of plasmonic index sensors consisting of a channel waveguide and a ring cavity. Two emissions from the ring cavity in both directions of the waveguide couple with a reflection phase difference depending on the length of a closed right arm with a reflecting boundary. Therefore, the output power dramatically and sensitively changes as a function of the refractive index of the analyte filling the waveguide.
为了将大量传感器集成到用于生物/化学应用的微小芯片中，人们对具有小尺寸的灵敏折射率传感器进行了研究。特别是，基于各种微/纳米腔的共振型折射率传感器已经被开发出来，这种传感器利用共振波长对分析物折射率的依赖性。然而，由于金属的吸收损耗较大，等离子体腔中作为分辨率极限的共振光谱线宽相当大。因此，需要一种不受腔线宽限制的新型等离子体折射率传感器。我们提出了一种由通道波导和环形腔组成的新型等离子体折射率传感器。来自环形腔在波导两个方向上的两种发射光，会根据具有反射边界的闭合右臂的长度产生反射相位差而相互耦合。因此，输出功率会随着填充波导的分析物折射率的变化而急剧且灵敏地改变。
