UV laser induced transmission change of pure and doped silica glass
ABSTRACT Pure and F, GeO2-doped silica glass cut from fiber preforms prepared by plasma assisted chemical vapor deposition(PCVD) were investigated
by ultraviolet absorption spectroscopy. The ultraviolet absorption characteristics of these glasses were also studied after
UV laser irradiation and heating treatment. It was found that absorption band near 240 nm assigned to GODC was found both
in GeO2-doped and F-GeO2 co-doped silica glass, but absorption intensity of the latter was lower than that of the former. It’s because F can react
with GODC and GeE’ simultaneously and reduce their concentration. After irradiation, UV absorption change of F-GeO2 co-doped silica glass was weaker than that of GeO2-doped silica glass,it thus can be concluded that introduction of F could depress the UV absorption of GeO2-doped silica core effectively.
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ABSTRACT: The amplitude of the 5 eV optical absorption band of oxygen-deficient germanium-doped silica samples (3GeO2:97SiO2) was varied by annealing in oxygen at 1000°C for different periods of time. Each sample was irradiated with the same dose of 5 eV light from a KrF excimer laser to study the effect of the absorption band amplitude on the photo-induced changes. ESR (Electron spin resonance) and optical absorption measurements were carried out after each annealing and each laser irradiation cycle. We find that samples with an initially higher 5 eV absorption band amplitude exhibit a larger increase in the absorption bands related to the photo-induced paramagnetic Ge E′ and GEC (Germanium Electron Center) when irradiated with the same laser dose. Deconvolution of the measured spectra shows that the concentrations of the photo-induced paramagnetic Ge E′ and GEC defects are well correlated with the concentration of GLPC (germanium lone pair center) defects associated with a 5.14 eV absorption band.Journal of Non-crystalline Solids - J NON-CRYST SOLIDS. 01/1999; 246(1):39-45.
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ABSTRACT: Several kinds of optical diagnostics are planned in a fusion reactor. Complicated optical systems such as periscopes are thought to be primary candidates for optical measurements, especially for visible wavelengths. However, optical fibers have several advantages over such optical systems. Also, the optical fibers could be a far better transmission line for signals under a high electromagnetic field. However, they have been considered vulnerable to heavy irradiation. In this study, several kinds of optical fibers were irradiated in the Japan Material Testing Reactor (JMTR). The optical transmissivity in fibers was measured in situ during fast neutron and gamma irradiation, up to doses of 2×1024 n m−2 and 5×109 Gy, respectively. The irradiation temperature ranged from 300 to 700 K. For pure ionizing irradiation environments, some methods for improving the radiation resistance of optical fibers were indicated. The results showed that effects of the irradiation associated with fast neutrons would be different from the effects of pure ionizing irradiation. Some fibers were found to withstand the heavy irradiation, especially in an infrared wavelength range.Fusion Engineering and Design. 01/1998;
- Journal of Non-Crystalline Solids 01/1985; 73:51-77. · 1.60 Impact Factor