We develop and investigate fiber-optic bend sensor, which is formed by a section of double cladding SM630 fiber between standard SMF-28 fibers. The principle of operation of the sensor is based on coupling of the fiber core and cladding modes at the splices of fibers having different refractive index profiles. We use two sources with wavelengths 1328 and 1545 nm to interrogate the sensor. The dependences of transmission on curvature at these wavelengths are significantly different. We show that the proposed sensor is able to perform measurements of curvature with radii from meters to 26 cm with accuracy of about 3%.

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Results of a computer simulation and experimental study are presented for a fiber sensor based on a Saint-Gobain Crystals BSF-60 scintillation fiber which was used to measure the activities of sources of ionizing radiation. The simulation was based on the Monte Carlo method and the Geant4 software code and was applied to calculate the dependence of the number of beta-electrons entering a BSF-60 scintillation fiber on the activity of radiation sources based on 63Ni, 89Sr and 90Sr isotopes. An experimental study of the sensitivity of the developed fiber sensor and the measuring system to beta-radiation of 63Ni, 89Sr and 90Sr isotopes showed a high degree of compliance with the proposed model.

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