Highly sensitive temperature sensor based on nematic liquid crystal channel waveguide on silicon

Abstract

This paper presents a highly sensitive hybrid plasmonic liquid crystal channel-based temperature sensor. The proposed structure has V-groove waveguide channel infiltrated with nematic liquid crystal (NLC) material of type E7 and coated by a gold (Au) layer to excite the surface plasmon resonance at the metal/dielectric interface. The NLC refractive indices depend on the temperature which affects the resonance wavelength where coupling occurs between the core and surface plasmon modes. The full vectorial finite element method is employed to evaluate the sensing performance of the reported sensor. The numerical results show that the suggested sensor can achieve an average temperature sensitivity of 24.5 nm/°C over a temperature range from 15 to 40 °C. The obtained wavelength sensitivity is higher than those of most similar temperature sensors based on silica-silicon or silicon-on-insulator technology in literature. In addition, the average amplitude sensitivity and figure of merit of the presented sensor are 0.135 °C− 1 and 0.43 °C− 1, respectively. Moreover, the introduced structure is complementary metal-oxide-semiconductor compatible with simple design and good fabrication tolerance of ± 5% where the temperature sensitivity is better than 23 nm/°C.