20 November 1996 Thermal annealing of UV-induced compaction in germanosilicate preform plates
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Bragg gratings were written in the cores of 7 percent mole germania doped preform plates through exposure to cw UV light. The diffraction efficiencies of the holograms were measured at a probe wavelength of 633 nm. The photoinduced refractive index modulations were calculated from these data. Microscopic inspections of the plate surfaces have shown that UV exposure induced corrugations at the grating places. A phase shift interferometric microscope was used to measure the depths of the corrugations. These measurements have shown that the corrugation depths do not depend on the nature of the gas surrounding the plate at the time of the UV exposure. Afterwards, both the refractive index modulations and the depths of the corrugations were measured in the course of 30 min isochronal step annealing experiments. The heating induced refractive index modulation changes were calculated from the changes in the corrugation depths by means of as train densification model and then compared to the experimental ones. Heating the gratings up to 600 degrees C has shown that the densification process is thermally reversible.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Marc Douay, Marc Douay, Wenxiang Xie, Wenxiang Xie, Pascal Bernage, Pascal Bernage, D. Ramecourt, D. Ramecourt, Pierre Niay, Pierre Niay, Bertrand Poumellec, Bertrand Poumellec, Jean-Francois Bayon, Jean-Francois Bayon, H. Poignant, H. Poignant, } "Thermal annealing of UV-induced compaction in germanosilicate preform plates", Proc. SPIE 2841, Doped Fiber Devices, (20 November 1996); doi: 10.1117/12.258980; https://doi.org/10.1117/12.258980

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