A photonic crystal fiber based on a surface plasmon resonance sensor coated with segmented silver-titanium dioxide ( A g - T i O 2 ) film is proposed for microfluid refractive index sensing. The sensing properties of the designed sensor are analyzed numerically by the full-vectorial finite element method. The results display that the wavelength sensitivity can be tuned by the thickness of the T i O 2 film and segmented number and angle of the A g - T i O 2 film. It is observed that an average sensitivity of 6329 nm/RIU for refractive indexes ranging from 1.330 to 1.360, and a maximum wavelength sensitivity of 10600 nm/RIU with a high wavelength resolution of 9.43 × 10 − 6 R I U , can be achieved in the sensing range of 1.350 to 1.355. In addition, it also shows a maximum amplitude sensitivity of 633.4001 R I U − 1 , and the maximum figure of merit is 303 with n a varying from 1.330 to 1.360, which can be applied to the field of chemical and biological analysis.

Two kinds of photonic crystal fiber (PCF) sensors based on surface plasmon resonance (SPR) with silver nano-continuous gratings (i) and (ii) are designed. The coupling characteristics and sensing properties are analyzed numerically by the finite element method (FEM). The results show that the proposed sensor based on silver nano-continuous grating (i) can achieve better performance than that of the sensors based on silver nano-continuous grating (ii) and plane silver film structures. When the segmented number is 50 and segmented angle is 0.5°, a wavelength sensitivity of the proposed sensor with silver nano-continuous grating (i) is obtained as high as 13,600 nm/RIU in the refractive index (RI) range from 1.330 to 1.365, corresponding to a maximum RI resolution of $7.35\times {10}^{-6}\mathrm{RIU}$, which can have promising applications in medical and environmental monitoring and biochemical detection.

Long-term operation of cables and equipment under abnormal currents can cause insulation aging and reduce the service life of the equipment. Identifying the current-carrying status accurately and early detection of potential failures of power cables is particularly significant for ensuring the operation of power equipment safely and economically. This paper proposed a method for detecting the current-carrying status of power cables and an early fault warning based on temperature information. Based on the theoretical basis of the relationship between temperature and current. According to IEC 61000-3-7 and IEC 60038 standards, the current-carrying state evaluation method is analyzed and given, and the early fault warning model is established. Finally, the paper takes the cable connector and the lightning arrester in the power ring network cabinet as an example to verify the method’s feasibility. It shows that the characteristic information of the relative temperature variation curves under different current carrying states significantly differs. Includes the slope of hour 9, the slope of hour 2, and the maximum. Then the total duration under abnormal current operation is calculated, and the early warning of faults can realize.