Tunable plasmonic sensor with metal-liquid crystal-metal structure

Abstract

A new tunable plasmonic biosensor is proposed by embedding liquid crystals in the slit region of a corrugated plasmonic nanoslit array. The absorption spectrum of the structure and, thus, the sensing wavelength can be controlled by applying voltage to the electrode parts of the device. The interaction between the waveguide mode inside the slit and the surface plasmon polaritons on the corrugation surface can be modified using the electrooptical effect of the liquid crystals. Our numerical simulations with the finite-difference time-domain (FDTD) method reveal a large tuning of the absorption spectrum up to 100 nm. In addition to the tunability feature, the structure has a high sensitivity of 570 nm/RIU. The sensing performance of the device is evaluated by performing homogeneous biochemical sensing simulations. The special feature of the proposed structure gives it an opportunity to be used as an efficient element in integrated photonics circuits for miniaturization and tuning purposes.