Highly sensitive strain sensor based on tapered few-mode fiber

Abstract

A high sensitivity strain sensor using a sandwich structure of “single mode fiber (SMF)—few mode fiber (FMF)—single mode fiber (SMF)” was proposed and experimentally validated. The designed sensor is achieved by splicing a segment of FMF between two segments of SMFs, and then using a fiber optic fusion tapering machine to double the length of FMF. Introducing tapered optical fibers into the structure to excite more evanescent waves improves the sensitivity of the sensor to the surrounding environment. In addition, due to the fact that the FMF is tapered into a very fine shape, the tensile stress applied to the FMF will increase. Therefore, conical FMF has excellent stress concentration ability, which is easily deformed under stress, thus achieving a high strain sensitivity of −23.9 pm/με. Finally, a cascaded FBG was used to compensate for the temperature cross-sensitivity of the sensor. This strain sensor with an extremely simple structure and high sensitivity has wide application value in the industry.

Performance Enhancement in a Few-Mode Rayleigh-Brillouin Optical Time Domain Analysis System Using Pulse Coding and LMD Algorithm

“…Few-mode fibers (FMFs) are used in distributed temperature measurements as a new type of optical fiber that is different from ordinary single-mode fibers. Because FMFs have large core diameters, high SBS thresholds, and transmits a limited number of orthogonal modes [13,14], it can achieve the sensing of parameters such as temperature, strain, and bending, and can overcoming the problem of multiparameter cross-sensitivity, with potential for simultaneous multiparameter measurements [15][16][17][18], which has received widespread attention from researchers [19][20][21]. When light waves are coupled in FMFs, different Brillouin scattering spectra (BGSs) will be formed for the optical signals in the different modes, which react differently to changes in the measurement parameters.…”