Coupled surface plasmon resonance sensor with sensitive liquid crystal layer

Abstract

This paper presents an optical sensor based on the surface plasmon resonance (SPR) phenomenon, involved with liquid crystal (LC) sensitive layer. This sensor has potential applications in chemical and biological systems. We present a tracking method for the state of alignment and degree of ordering of the partially ordered LC film. This can be achieved via the SPR propagation constant and the critical angle at the interface between a metal and an LC film. The proposed idea is also investigated experimentally. For this purpose, we fabricated gold nano-dots array on an optical fiber tip for localized SPR sensing. The spectral position of the maximum loss in the transmission spectra depends on the refractive index of the medium surrounding the sensor fiber tips. This allows for tracking the LC profile parameters.