Thermal poling of boron-codoped germanosilicate fibre

The dependence of a linear electro-optic (LEO) coefficient induced into bor on-codoped germanosilicate fibre on thermal poling conditions (poling volta ge, poling temperature and poling time) has been systematically carried out using a Mach-Zehnder interferometer. The LEO coefficient increases as a si milar to 2.7 power law with the poling voltage; it can be maximally induced into the silica fibre within a temperature range from 250 degrees C to 300 degrees C; it exponentially increases with poling time until saturation bu t after that it then decreases. Possible mechanisms of thermal poling are d iscussed in the light of the experimental results.