Numerical Investigation of a High Performance Subwavelength Grating Based Plasmonic Biosensor

Abstract

A Localized Surface Plasmon Resonance (LSPR) biosensor based on a subwavelength grating structure is studied numerically for detection of bulk refractive change of aqueous environments such as biological buffer solutions. A high grating thickness of 40nm and a short grating period of 50nm are selected to evaluate numerically the effect of the other grating structural parameter i.e. fill factor (f.f) on the sensor performance including dispersion curve, sensitivity, FWHM, MRR and resonance angle. Evaluation shows that corresponding wavelength to the effective resonance of surface plasmons which locating in near infrared (NIR) wavelength range is displaced with f.f value. Also, as shown for some f.f values sensitivity is enhanced slightly whereas FWHM, MRR and resonance angle is increased. Thus with adjusting both of operating wavelength and f.f value, it is possible to get a better performance for the plasmonic sensor.