R. R. Khrapko

Dedicated optical fibers for dosimetry based on radiation-induced attenuation: experimental results

Nuclear industry may benefit from the implementation of Optical Fiber Sensor (OFS) technology. This is obvious if the OFS integrates features that meet specific nuclear sensing needs, such as distributed dose monitoring in underground radioactive waste disposals. The use of radiation sensitive fibers for dosimetry has already been proposed in literature. In this paper, we report on our gamma irradiation of such dedicated Ge-P co-doped and pure P-doped optical fiber, fabricated by the Fiber Optic Research Center in Moscow. We show that after a careful selection of the wavelength at which the radiation-induced attenuation is measured, it is possible to reconstruct the dose within 20% accuracy by means of a linear model or a second order polynomial, depending on the temperature.

Nitrogen-doped silica fibers and fiber-based optoelectronic components

The technology, properties and applications of novel germanium-free nitrogen-doped silica fibers are reviewed. The key features of the plasmachemical synthesis of low- hydrogen N-doped silica fiber preforms are discussed. Optoelectronic components fabricated from N-doped silica fibers are considered: thermostable Bragg and long-period gratings, mode field converters, and filters to smooth the erbium amplifier gain spectrum. Other important properties of the new fibers, such as high resistance to ionizing radiation and efficient third harmonic generation, are also discussed.

Fluorine-doped silica optical fibres fabricated using plasma-chemical technologies

Fluorine-doped silica active and passive optical fibers for different purposes have been fabricated by two novel modifications of the plasmachemical technology. These versions of the technology are shown to be convenient in laboratory conditions and very promising in developing various types of special fibers with non-standard parameters based on pure and fluorine-doped silica.

Radiation resistance of optical fibres with fluorine-doped silica cladding

Spectra and kinetics of decay of (gamma) -irradiation induced loss in optical fibers with pure silica and Ge- and/or F-doped silica core and F-doped cladding made by MCVD and SPCVD methods were measured at room temperature. Induced loss in short-wavelength range is shown to decrease at Ge-content decrease and at F addition to the core glass. Minimum of induced loss is located in long-wavelength range, the best result (about 2 dB/km after the dose 10 kGy) being achieved on pure silica core MCVD fiber. Induced absorption band at 630 nm is observed in pure silica core fibers and it is suppressed by F-doping of the core glass.