High-Sensitive Fiber Anemometer Based on Surface Plasmon Resonance Effect in Photonic Crystal Fiber

A novel hot wire fiber anemometer was proposed based on surface plasmon resonance (SPR) effect in a dual-defect hole photonic crystal fiber (PCF), and the flow rate sensing characters of high sensitivity, wide measurement range, and strain compensation were proved by the numerical analysis. A gold film was selected as the plasmonic material to stimulate SPR, and diethylene glycol was considered as temperature-sensitive material. By theoretical and simulation analyses, the relationship between flow rate and ambient temperature was discussed, and the variations of structural parameters in the PCF were analyzed along with the changes of temperature and strain. Through further simulation research, the temperature sensitivity of the proposed SPR sensor was calculated as 6.83 nm/°C. Besides, the simulated flow rate sensitivity and resolution were improved to 32.19 nm/(m/s) and
$6.21\times 10^{-4}$
m/s, respectively, when the flow rate was around 1 m/s and laser power was 100 mW. The maximum detectable flow rate could be up to 23.4 m/s when the resolutions of flow rate and wavelength were 0.3 m/s and 0.02 nm, respectively. Finally, the cross-sensitivity problem between flow rate and strain could be theoretically solved by detecting the wavelengths of dual SPR.