Isochronal annealing of Bragg gratings written in H2-loaded or in UV-hypersensitized germano-phosphosilicate planar waveguides:: a comparison

Bragg Gratings (BGs) have been written within either H-2-loaded or UV- hypersensitized phosphorous-germanium co-doped silica planar waveguides through exposure to light at 248 nm. The stability of these BGs has been investigated by means of isochronal annealing experiments. It appears that the stability of both the modulation and the Bragg wavelength is higher in the hydrogenated waveguides than in the hypersensitized counterparts. Moreover, in the case of BGs in the UV- hypersensitized waveguides, the rate of the strength decay depends on the initial amplitude of the refractive index modulation whereas no significant difference could be observed in H-2- loaded waveguides. It is shown that the master-curve formalism can be used to predicting an isothermal decay of both reflectivity and Bragg wavelengths of BGs written in the H2- loaded waveguides. This conclusion is illustrated by the fairly nice agreement that exits between the results of an isothermal annealing experiment and those predicted by use of the master-curve. (c) 2005 Optical Society of America.