Improving Tuning Range and Sensitivity of Localized SPR Sensors With Graphene

Abstract — This letter theoretically and numerically confirms that graphene can improve the tuning range and sensitivity of localized surface plasmon resonance (SPR) sensors. For an SPR sensor with metal nanoparticle arrays fabricated on top of a graphene-coated glass slide, the voltage applied to the graphene layer changes the graphene’s optical conductivity and induced polarization of the nanoparticles. As a result of these modifica-tions, the transmission and reflection characteristics of the device change. Numerical studies reveal that for the longitudinal mode, an increase of 2 eV in the chemical potential cause a 24-nm blue shift in the resonance wavelength with a sharper dip in the transmission spectrum and a 23 % increase in the sensitivity. Index Terms — Graphene, optical sensors, surface plasmon resonance (SPR), tunable sensors. I