Study of UV-written channels in lead silicate glasses

Light-induced refractive index change was investigated in two lead-silicate (SF57 and F2) glasses by irradiation using a pulsed 248 nm KrF excimer laser and a CW frequency doubled argon ion laser at 244 nm. UV–Vis spectra were recorded after each exposure to the excimer laser to study the change in absorption. The exposures were cumulative. The results showed that, with increasing number of pulses, there was an increase in the attenuation of the samples. Large photosensitivity was observed from direct 244 nm UV-written channels without the use of a phase mask. The refractive index change measured at 633 nm for SF57 glass was to 2.9×10-2 and a channel waveguide loss of 4.8 dB/cm and for F2 glass was to 7×10-3 and a loss of 5 dB/cm. The large refractive index changes measured here are achieved at the expense of large induced losses. The channel waveguides were thermally stable up to 300 °C.