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A novel surface plasmon polaritons (SPPs) refractive index sensor based on a single defect nanocavity coupled with a metal-insulator-metal (MIM) waveguide is proposed and numerically simulated by using the finite difference time domain (FDTD) method with perfectly matched layer absorbing boundary condition. It is found that the defect structure can realize two Fano resonances and these two Fano resonances originate from two different mechanisms. The results demonstrate the liner correlation between the resonance wavelengths of the device and the refractive index of the material under sensing. Through the optimization of structural parameters, we achieve a theoretical value of the refractive index sensitivity as high as 1800.4 nmRIU. It could be utilized to develop ultra-compact nanodevice for high-resolution biological sensing. [ABSTRACT FROM AUTHOR]

Abstract: A novel two-dimensional nanoscale structure for sensing which consists of a metal–insulator–metal (MIM) waveguide with a defect, is designed and numerically simulated by using the finite element method (FEM). Both of the refractive index sensing characteristics and the temperature sensing characteristics of the structure are analyzed systematically by investigating the transmission spectrum. The numerically simulated results show that the dip positions of the transmission spectrum have linear relationships with the refractive index of the material under sensing and the ambient temperature, respectively. Based on the relationships, the refractive index of the material under sensing or the ambient temperature can be obtained from the dip wavelength shift detection. When the width and the height of the defect are set to be 50nm, 300nm, respectively, the refractive index sensitivity can be obtained as high as 1736nmRIU−1 and the temperature sensitivity is about 0.51nm/°C with a FOM of 9.79. This work has a certain significance for designing nanoscale refractive index sensors and temperature sensors. [Copyright &y& Elsevier]