Ultraviolet-visible light-induced solarisation in silica-based optical fibres for indoor solar applications

The transmission performances of pure- and doped-silica (a-SiO2) optical fibres are compared during the exposure to a high-power broadband light source approximating the solar spectrum. From the Gaussian decomposition of the attenuation spectra, we found that Al- and P-doped fibres show a fast solarisation effect which leads to transmission degradation in the ultraviolet-visible range. Similarly, Ge-doped fibres undergo photoinduced colour-centre formation which, however, does not prevent visible-light propagation. One of the two tested pure-silica fibres results completely unaffected by light exposure whereas the other shows an absorption band probably due to the presence of chlorine impurities in the silica matrix.The reported results demonstrate the possibility of using commercial Ge-doped and pure-silica fibres for indoor lighting applications and fibre-based photovoltaic devices.