High performance surface plasmon resonance sensor based on two dimensional ultra-thin metal nanoslit arrays

We present a high performance surface plasmon resonance (SPR) sensor based on two dimensional (2D) ultra-thin (40 nm) gold nanoslit arrays. These structures were designed to exhibit narrow linewidth (FWHM) and high transmission SPR under non-polarized illumination. In addition, we show the influence of the geometrical design on the performance of these 2D slit arrays. The measured sensitivity (S_λ) of 2D slit arrays with a grating period of 620 nm is 600 nm/RIU, while the FWHM is as small as 22 nm. The obtained figure of merit (S_λ/FWHM) of 27/RIU is one of the highest reported values for such structures. Furthermore, we experimentally prove that 2D nanoslit arrays show narrower FWHM and higher transmission than 1D slit arrays under non-polarized illumination. The high figure of merit and polarization independence makes the 2D slit arrays especially suitable for further SPR sensor miniaturization through integration with a VCSEL or white light source, while keeping a high sensitivity.