Design of dual-core photonic crystal fiber for temperature sensor based on surface plasmon resonance effect

A toluene-ethanol filled dual-core photonic crystal fiber (PCF) based on surface plasmon resonance effect is designed for temperature sensing. The toluene with higher refractive index is injected into the central air hole in order to support the core mode. In contrast, the ethanol, whose refractive index is lower, is injected into the sideward air hole coated by gold film to support the mode induced by surface plasmon polariton. The resonance characteristics of surface plasmon in the designed PCF are numerically investigated by using finite element method. It is shown that the influences of structure parameters on temperature sensing performance are different. On the other hand, the resulting resonance wavelength of the spectrum of confinement loss moves to longer wavelength to satisfy the phase matching when the detective temperature is increased. After optimizing structure parameters, the sensitivity of temperature sensor can reach 6.32 nm/°C in the range from 10 °C to 70 °C, indicating its potential applications in temperature measurement with wide temperature range.