Magnetic field sensor by combing magnetic fluid and optical fiber Loyt-Sagnac interferometer is proposed. The sensor takes advantage of the birefringence effect of magnetic fluid. The relative small birefringence of the magnetic fluid is â€˜magnifiedâ€?by the properly designed optical fiber Loyt-Sagnac interferometric structure. As compared to the reported MF-based sensors, the achieved sensitivity of the proposed sensor is 592.8 pm/Oe, which is enhanced by 1â€? orders of magnitude.
A novel load sensor has been proposed and demonstrated by embedding a fiber Bragg grating (FBG) into a tapered cylindrical polymer rod. Load-induced nonuniform strain field changes the bandwidth, and hence, the reflected optical power of the FBG. Temperature-insensitive measurement of load has been realized by measuring the reflected optical power with only a low-cost optical power meter. Load measurement sensitivity of 5.0 nW/N has been experimentally achieved within a range up to 1800 N.
A photonic crystal fiber pressure sensor using mechanical induced tilted long period grating is reported. Trans- mission dip has a blue shift when the tilted angle of the long period grating increases. The performances of the pressure sensor are evaluated by the shifting of the transmission spectrum after applying different pressure level. The experimental results show that the larger the tilted angle of the grating, the transmission dip experiences the larger blue-shift, leading to higher sensitivity up to 2.701 nm/MPa.
A magnetic field sensor based on combination of the magnetic fluid and the tunable photonic bandgap effect of photonic crystal fiber is proposed. The magnetic fluid with higher refractive index (>1.45) is prepared and filled into the air-holes of photonic crystal fiber to convert the index guiding fiber into photonic bandgap fiber. The proposed sensor takes full advantage of the ultrahigh sensitivity characteristic of photonic bandgap fiber and achieves a high sensitivity and resolution of 1.56 nm/Oe and 0.0064 Oe, respectively, which are 2-3 orders of magnitude better than other sensors based on magnetic fluid.