Writing of birefringent lines in LBG glasses by UV pulsed laser irradiation

Glass isotropy could be broken by using the electric field of the 355 nm wavelength delivered by a nanosecond YAG: Nd3+ laser. In this way, pulsed laser-induced birefringence was obtained in the La2O3–B2O3–GeO2 (LBG) glassy system. Buried lines behaving like waveguides were written in glasses using this laser irradiation process. Micro Raman spectra performed in irradiated points of glasses revealed a rotation of the light polarization in agreement with previous results obtained on thermally-poled LBG glasses. However, no orientation effects of irradiated points related to the direction of the laser wave polarization (UV poling) could be clearly evidenced as suggested in our last paper. The interaction of the glass with the electromagnetic field of the UV laser beam can be more probably described by mechanisms based on a densification process.