We propose a simple optical fiber current sensors based on the Lorentz force to measure the current. We use two copper carrying wires, and the two carrying wires are parallel fixed to the insulated coil spring. Then, the two optical fibers are vertically fixed on two copper, respectively. When the current input the wires, Loren magnetic force will be existed between wires. The force causes deformation of the spring and leads to the displacement of the fiber’s end faces. So the spectra should be changed. The experimental device is used to measure the current at range for the 1-5 A, the response time is about 0.1 seconds, and resolution sensitivity of the sensor is 10 nm/A. The results show that the device is simple and low costs. It has a potential applied in high current sensing.
A U-shaped optical fiber sensing system designed to measure the refractive index of liquid had been
proposed. The sensing mechanism of U-shaped optical fiber was discussed. A general single-mode
fiber was bent into U-shaped and partially cladding of U-shaped fiber was corroded by HF acid buffer
solution. Powers of different diameters of U-shaped fibers had been measured by many experiments.
The results showed that the diameter of U-shaped fiber cladding 40 μm and the diameter of U-shaped
was 1 cm were suitable to measure liquid refractive index. Then, this U-shaped optical fiber was
immersed in liquid, such as pure water, ethanol, acetone and isopropanol, respectively. The evanescent
field of the U-shaped fiber should be modulated by the liquid. The optical signal in the U-shaped fiber
was measured with the optical spectrum analyzers(OSA). Finally, the experimental results were
analyzed, and the spectra in the air was selected as a reference. The relative intensity was obtained for
the different liquid. These results showed that the relative intensity of the liquid had a good linear
relationship. This sensing device could accurately demarcate refractive index of liquid. It is simple, low
cost, and it can also be applied in measuring the level of liquid.