Deep Subwavelength-Scale Metal-Insulator-Metal Plasmonic Disk Cavities for Refractive Index Sensors

초록

We propose an ultrasmall plasmonic cavity index sensor based on double metal disks, in which a plasmonic mode with a wavelength (lambda(0)) of 1550 nm can be confined. By carefully reducing the radius (R) and gap thickness (t), the cavity can be reduced to a size of R = 744 nm and t = 20 nm, achieving a deep subwavelength-scale sensing volume of 0.0093 lambda(3)(0), while keeping the same wavelength. The figure of merit of the index sensor has a maximum value of 80 with a high sensitivity (1160 nm per refractive index unit) and narrow linewidth (14.8 nm).

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