Simulation of the Sensing Performance of a Plasmonic Biosensor Based on Birefringent Solid-Core Microstructured Optical Fiber

A finite element method is used to analyze the performance of a microstructured optical fiber-based surface plasmon resonance sensors aimed for biomedical applications, such as the detection of blood carried species. Birefringence obtained by removing of a row of holes in a two-ring hexagonal lattice of holes in a gold covered silica fiber leads to a relatively high sensitivity of the fiber optical response to a refractive index of the analyte surrounding the fiber. This fiber structure supports two types (I and II) of resonant modes. In these modes, there is an opposite variation of some sensing parameters with the increase of the refractive index of the analyte between 1.36 and 1.39. Thus, for a smaller value (1.36) of the refractive index of the analyte n a, the resonance spectral width δλ 0.5 is large for the core mode I and small for the core mode II but for a larger value (1.39) of n a, δλ 0.5 is small for the core mode I and large for the core mode II. Also, for n a = 1.36, the amplitude sensitivity S A is small for the core mode I and large for the core mode II but for n a = 1.39, S A is large for the core mode I and small for the core mode II. By adjusting the radius of the gold layer, the proposed sensor shows high spectral sensitivity S λ and narrow δλ 0.5 at the same resonance wavelength and n a (1.39) where the figure of merit (FOM) is very large in comparison with the most recently published values.