Effects of densification atmosphere on optical properties of ionic copper-activated sol-gel silica glass: towards an efficient radiation dosimeter

Ionic copper-doped pure silica glass, with high photoluminescence (PL) quantum yield (QY), has been prepared using the sol-gel technique and densification of the porous xerogel under inert atmosphere. The optical properties of the obtained glass, and especially the green light emission due to Cu+ ions under UV excitation, have been studied and compared to those of the glass produced in air atmosphere conditions. We have shown that the sintering process under helium increases the quantum efficiency of this emission by a factor 40. Moreover, the resulting copper-doped silica rod has been used in the fabrication of a high numerical aperture microstructured optical fiber, which shows similar luminescent properties to the sol-gel preform. The obtained fiber exhibits promising characteristics to be employed in an all-fibred UV sensor. In particular, the high emission efficiency and the specific air-clad geometry of the fiber made it possible to perform measurements without removing the polymer coating.