Photoinduced absorption and refractive-index induction in phosphosilicate fibres by radiation at 193 nm

The photoinduced room-temperature-stable increase in the refractive index by similar to 5 x 10(-4) at a wavelength of 1.55 mu m was observed in phosphosilicate fibres without their preliminary loading with molecular hydrogen. It is shown that irradiation of preliminary hydrogen-loaded fibres by an ArF laser at 193 urn enhances the efficiency of refractive-index induction by an order of magnitude. The induced-absorption spectra of preforms with a phosphosilicate glass core and optical fibres fabricated from them are studied in a broad spectral range from 150 to 5000 run. The intense induced-absorption band (similar to 800 cm(-1)) at 180 mn is found, which strongly affects the formation of the induced refractive index. The quantum-chemical model of a defect related to this band is proposed.