8. Temperature Sensors Based on Plasmonic Photonic Crystal Fiber

In this chapter, two novel highly sensitive surface plasmon resonance photonic crystal fiber (PCF) temperature sensors based on liquid crystal (LC) or alcohol mixture are presented and studied. Through this chapter, the coupling characteristics between the core-guided mode inside the PCF core infiltrated with either nematic LC or alcohol mixture and surface plasmon mode around the surface of nanogold wire are studied in detail. The structural geometrical parameters of the proposed designs, such as hole pitch, number of metallic rods, core diameter, and metallic rod diameter, are optimized to achieve highly temperature sensitivity. The suggested alcohol-based sensor offers high sensitivity of 3 nm/°C and 4.9 nm/°C for transverse electric (TE) and transverse magnetic (TM) polarizations, respectively. Moreover, the alcohol core sensor operates over a wider range of temperatures from −4 °C to 53 °C. In addition, the suggested LC-based sensor of compact device length of 20 μm proved to surpass the sensitivity of the recent temperature sensors. Using the LC instead of alcohol has improved the sensitivity to 10 nm/°C. The results are calculated using full-vectorial finite-element method with irregular meshing capabilities and perfect matched layer boundary conditions.