Bragg gratings printed upon thin glass films by excimer laser irradiation and selective chemical etching

Photon-induced property changes of sputter-deposited GeO(2)-SiO(2) thin glass films were investigated. Irradiation with ArF laser pulses induced the changes in refractive index of -10% and volume of +30% in the film without ablation. A Bragg grating with a positive sinusoid wave pattern was printed upon the film by irradiation with ArF excimer laser pulses through a phase mask. The irradiated area could be quickly etched by a HF solution. The ratio of etching rate of irradiated area to unirradiated area was higher than 30. A Bragg grating with a surface relief pattern was successfully formed on the film by irradiation with excimer laser pulses followed by chemical etching. Diffraction efficiency of the gratings increased by 25 times with the etching.