Determination of the visible range optical absorption spectrum of peroxy radicals in gamma-irradiated fused silica

Origin of the visible absorption in radiation-resistant optical fibers

“…Nagasawa et al [4,5] have asserted that the peak and the FWHM values can change with the OH-group content. Later, in similar samples the presence of other absorptions have been proposed in the same spectral region, these bands have been attributed to: the peroxy radical, POR (≡Si-O-O·), [6] and the selftrapped holes, STH (≡Si-Ȯ-Si≡) [7][8][9]. The attempt to single out the absorption related to specific defects has been mainly based on the deconvolution of the OA lineshape in gaussian bands [10].…”

Effect of neutron-irradiation on optical properties of SiO2-Na2O-MgO-Al2O3 glasses

“…In general, these absorption bands are associated with either oxygen deficiency or oxygen excess in the glass network [2,3]. The most fundamental radiation induced defects in glasses are the non-bridging oxygen hole center (NBOHC: Si-O*), the E' center ( Si*), the peroxy radical (POR: Si-O-O*), and the trapped electron (TE), where the notation " " represents three bonds with other oxygens in the glass network and "*" denotes an unpaired electron [2][3][4]. In the glass exposed to radiations, hole trapped color centers with characteristic absorption bands around 430 nm were formed upon irradiation, leading to the development of the brown color.…”

Irradiation Effects in Optical Fibers

“…In particular, it has been shown that the defect formation processes feature a complex dynamics related to the presence of precursor of the defects and also affected by the inhomogeneity intrinsic to the amorphous nature of the material. Furthermore, the stability of irradiation induced defects is affected by the presence of species present in the material and, in particular, it has been evidenced that H related species (H, H 2 , H 2 O) usually affects the formation and thermal removal of many defects as NBOHC, E' and ODC(II) (Griscom et al, 1998;Devine et al, 2000;Pacchioni et al 2000;Nuccio et al 2009;Messina et al 2009). …”

“…In nuclear environments optical fibers found an application niche in optical communication links, embedded into various all-fiber or hybrid sensors or as light-guides for control and diagnostics (Alfeeli et al, 2007;Ahrens et al, 2001;Fernando et al, 2005;Fielder et al, 2005;Florous et al, 2007;Gan et al 2008;Henschel et al, 2001;Kimurai et al 2002;O'Keeffe et al 2008;Reichle et al, 2007;Troska et al, 2003). For applications related to fusion installations the requirements are quite demanding because of the exposure to (Campbell, 2005;Griscom, 1998;Hodgson, 2006;ITER Physics Expert Group on Diagnostics, 1999;Shikama, 2003;Zabezhailov, 2005): ionising radiation, high temperature, and high electromagnetic disturbances. One of the major drawbacks for optical fibers use under ionizing radiation is related to the development of colour centres, which affect dramatically the optical transmission in UVvisible-NIR spectral ranges (Griscom, 1998;Karlitschek, 1995).…”

“…For applications related to fusion installations the requirements are quite demanding because of the exposure to (Campbell, 2005;Griscom, 1998;Hodgson, 2006;ITER Physics Expert Group on Diagnostics, 1999;Shikama, 2003;Zabezhailov, 2005): ionising radiation, high temperature, and high electromagnetic disturbances. One of the major drawbacks for optical fibers use under ionizing radiation is related to the development of colour centres, which affect dramatically the optical transmission in UVvisible-NIR spectral ranges (Griscom, 1998;Karlitschek, 1995). For this reason, optical fibers are by more than 30 years in the focus of colour centres research (Friebele, 1976;Kaiser, 1974).…”