A Study on Photosensitivity of Ge-doped SiO2 films foe Waveguide Bragg Grating Device

Abstract

Bragg grating is now widely used for a variety of apllication including filters, sensor, gain flattening, and dispersion compensation and becomes an indispensable technology for optical communication. Meanwhile the planar lightwave circuit devices gradually replace the fiber devices due to its relatively high performance and low price. Therefore, the variety of funtionality realized in fiber devices are also required in PLC devices. Bragg grating is one of the most urgent element to be realized in PLC devices. Bragg grating is fabricated by the induction of periodical refractive index change in the core layer when exposed to UV light with a large connection of germannium. In this study, phtosensitivity dynamics in glass with the composition similar to that of PLC devices was investigated as a fundamental study prior to the device fabrication. Silica bulk glasses for the core layer of PLC devices were prepared in a way that the amount of SiO2, GeO2, and P2O5 were kept constant but the amount of boron is controlled. After all, the glasses are irradiated by 248nm KrF laser and induced-refractive index changes are measured by prism coupler method