We propose an all-fiber electric field sensor using a U-bent single-mode fiber integrated with liquid crystal. The sensing mechanism is based on the interference between whispering-gallery modes and core mode in U-shaped bent fibers. We have experimentally investigated the influences of applied electric voltage as well as polarization state of the incident light on the transmission spectral characteristics of the proposed electric field sensor. The experimental results indicate that the transmission spectra are highly sensitive to the applied voltage and the highest sensitivity reaches 20.4221 nm/kV. The dip wavelengths and transmission loss at transmission dip exhibit a periodic variation behavior in response to the light polarization state rotation by 360 deg, which is in agreement with our theoretical analysis.
An ultrasensitive optical fiber twist sensor is proposed by employing a Sagnac interferometer based on polarization-maintaining elliptical core fibers (PM-ECFs). The twist effects are theoretically analyzed and experimentally demonstrated. Based on the photoelastic effect, the wavelength shift in response to twist rate turns out linear tendency and is torsion-direction-dependent. The maximum torsion sensitivity reaches 18.59593nm/(rad/m) (or 0.67582nm/°) for clockwise (CW) torsion direction and 15.83073nm/(rad/m) for anticlockwise (ACW) torsion direction, respectively. Furthermore, it is further improved up to 1.675 nm/° by rotating two ends of PM-ECF simultaneously. The prominent advantage of ultrasensitivity keep it meritorious in the applications of spaceflight and constructional engineering.
In this paper, we have demonstrated a magnetic field sensor based on the fiber taper coupler coated with Magnetic fluid. The proposed sensor is fabricated by immersing a fiber taper coupler into the Magnetic fluid and then sealing it with the paraffin. The sensor exhibits high response as a function of the magnetic field with sensitivities of 0.154 nm/Oe with measurement range from 50 Oe to 200 Oe and -0.06301 dB/ Oe from 75 Oe to 200 Oe. Owing to the advantages of high sensitivity, small footprint, and ease of fabrication, the proposed sensor would find potential applications in magnetic field sensing field.
A compact fiber-optic magnetic-field sensor based on tapered all-solid waveguide-array fiber (WAF) and magnetic fluid (MF) has been proposed and experimentally demonstrated. The transmission spectra of the fiber-optic magnetic field sensor have been measured and analyzed under different magnetic field intensities. Experimental results show that the acquired magnetic field sensitivity is 44.57 pm/Oe for a linear magnetic field intensity range from 50 Oe to 200 Oe. It also indicates that the magnetic field sensor based on tapered all-solid WAF and MF is helpful to reduce temperature cross-sensitivity for the measurement of magnetic field.
A magnetic-field-tuned photonics device based on magnetic fluid (MF) and a square tapered no-core fiber (NCF) sandwiched between two single-mode fibers (SMFs) has been proposed. The enhanced evanescent field effect in the NCF is achieved by tapering the square NCF utilizing a fusion splicer. The spectral dependence of the proposed device on the applied magnetic-field intensity has been investigated. The results indicate that a maximal sensitivity of -18.7pm/Oe is obtained for a magnetic field strength ranging from 25Oe to 450Oe. The proposed tunable device has several advantages, including low cost, ease of fabrication, compact structure, and high sensitivity.