Fast-neutron radiation effects in a silica-core optical fiber studied by a CCD-camera spectrometer

Abstract

A simple CCD-camera spectrometer was deployed at the Los Alamos Spallation Radiation Effects Facility to characterize fast-neutron irradiation effects in several silica-based optical fibers over the wavelength range 450-1100 nm. The experimental arrangement allowed optical loss spectra to be developed from remotely recovered frame grabs at various times during irradiation without it being necessary to resort to cutback methods. Data recorded for a pure-silica-core/F-doped-silica-clad fiber displayed a peculiar artifact, which is described and mathematically modeled in terms of leaky modes propagating in an optical cladding that is substantially less susceptible to radiation-induced optical attenuation than is the core. Evidence from optical time-domain reflectometry supports the postulate that mode leakage into the cladding may be a result of light scattering from the tracks of ions displaced by the 14-MeV neutrons. These results suggest that fibers with fluorine doping in the core, as well as in the cladding, would be relatively resistant to radiation-induced attenuation in the UV-visible spectral region.

Fiber Bragg gratings of type I in SMF-28 and B/Ge fibre and type IIA B/Ge fibre under gamma radiation up to 0.54 MGy

“…Optical fibres have long been used as communication links in these environments [1] . Although radiation induced attenuation is observed, this can be counteracted by increasing power levels [2] . Wavelength encoded sensor technology i.e.…”

Radiation effect in silica optical fiber exposed to intense mixed neutron-gamma radiation field

“…Most of the studies deal with radiation effects at low as well as moderate accumulated dose (see references in [1] and [2]). Fewer publications are available concerning high gamma dose and neutron fluence [3]- [8]. However, sensing capability and data transmission could be also conceived under intense radiation field, e.g., inside a fission reactor.…”

1064 nm laser-induced defects in pure SiO_2 fibers

“…The stressed bonds which are the precursors to these sites result from three-or four-member ring structures in the silica matrix where the Si-O-Si bonds are not allowed to exist with their natural angle [4]. Previous work has shown that defects can be induced from stressed bonds through exposure to gamma rays [5,6] and high-energy particles [7] but also through one or two photon absorption occurring during the guidance of light from UV excimer lasers (KrF 248 m, ArF 193 nm, and F 2 157 nm) [8,9]. Other work has also been reported which demonstrates defect formation in bulk media due to few photon absorption from ultrashort, microjoule titanium sapphire laser pulses with high peak powers (50-300 MW) in the near infrared (800 nm) [10].…”