Models for the r-POHC (right side) and l-POHC (left side) paramagnetic defects. Small spheres represent oxygen atoms, while large spheres represent phosphorus or silicon. In the r-POHC the unpaired spin is shared between the two nonbridging oxygens of the structure [figure adapted from Griscom et al. (Ref. 8)].
Models for the P1, P2, and P4 paramagnetic centers [figure adapted from Griscom et al. (Ref. 8)].
Phosphorus doping profile in optical fiber. The inset shows the enlarged view of the canonical fiber sample. Numbers from 0 to 4 refer to the zones listed in Table I and related to the different P-content.
Spectral dependence of the 10 keV x-ray RIA for different total deposited doses.
(a) Permanent radiation-induced absorption coefficient measured in preform samples after an irradiation dose of 2 MGy (dose rate of 0.1 kGy/s). The inset shows the spectrum detected in pristine preform sample. (b) Spectral dependence of RIA during 10 keV x-ray irradiation detected in P-doped fibers (dose rate of 10 Gy/s) after a total deposited dose of 0.5 kGy.
ESR extended spectrum detected in P-doped preform x-irradiated at a dose of 20 kGy. The doublet due to P2 center is clearly visible.
Electron spin resonance spectra detected in (a) preform and (b) fiber after a total deposited X-dose of 20 kGy.
Decomposition with Gaussian absorption bands of the RIA spectra measured at the dose of 1 kGy. Dashed lines represent the Gaussian components.
Amplitude variation in the three RIA bands as a function of the x-ray dose detected in fiber samples at a dose rate of 10 Gy/s.
ESR intensity related to POHC centers as a function of the X total deposited dose detected in fiber samples.
Correlation between the POHC concentration evaluated by ESR measurements in fiber samples and the intensity of the three observed RIA components at 2.3 and 3.0 eV as obtained from the fit procedure illustrated in Fig. 8. The dashed flash indicates irradiation at 2 kGy. Full red lines represent the linear best fit. POHC concentration for doses refers to the sum of the contributions of r-POHCs and l-POHCs.
Correlation between the amplitude of the RIA band at 4.5 eV and the RIA amplitudes of (a) the 2.3 eV and (b) the 3.0 eV peaks. Red lines represent the linear best fit curves.
Parameters related to P-doped fiber and preform samples.
Article metrics loading...
Full text loading...