Confocal Raman imaging of femtosecond laser induced microstructures in germanate glasses

Microstructures were induced in a germanate glass by irradiation with focused 800 nm, 250 kHz femtosecond laser pulses. Compared with unirradiated glass, an increase in intensity and a frequency shift of the Raman scattering bands have been observed in a ring-shaped region inside the laser-modified structure. The pictogram shows the spatial map of the peak intensity and frequency shift of Raman bands in regard to the bulk germanate glass over the laser-modified region.