10. Multifunctional Plasmonic Photonic Crystal Fiber Biosensors

In this chapter, two novel designs of compact surface plasmon resonance multifunctional biosensors based on nematic liquid crystal (NLC) and Alcohol mixture photonic crystal fibers (PCFs) are proposed and studied. The suggested sensors have a central hole filled either with NLC or alcohol mixture as temperature-dependent materials. Further, another large hole filled with liquid analyte has a gold nanorod as a plasmonic material. Therefore, the proposed sensors can be used for temperature and analyte refractive index sensing via the coupling between the core-guided modes in the central hole and the surface plasmon modes around the gold nanorod. The effects of the structure geometrical parameters are studied to maximize the sensitivity of the PCF biosensors. The numerical analysis is carried out using full-vectorial finite element method with perfectly matched layer boundary conditions. The reported multifunctional NLC-based sensor offers high sensitivity of 5 nm/°C and 3700 nm/RIU (refractive index unit) for temperature and analyte refractive index sensing, respectively. In addition, the alcohol mixture PCF sensor achieves high-temperature sensitivity of 13.1 nm/°C with high analyte refractive index sensitivity of 12700 nm/RIU. To the best of the authors’ knowledge, it is the first time to introduce PCF biosensor with high sensitivity for temperature and analyte refractive index sensing as well. Further, the achieved sensitivity values of the alcohol sensor are far higher than those reported in the literature.