A comparison between thermal poling of silica in air and in vacuum is reported. It is shown that the second-order susceptibility and thickness of the nonlinear layer as well as their time evolution are highly dependent on the surrounding poling atmosphere. In the vacuum case a charge distribution (under the anode) more complex and broader than that for the air case has also been revealed by laser induced pressure pulse measurements. A multiple charge carrier model can explain the formation and evolution of the depletion region under the anode. The findings are relevant to achieve improved nonlinearities in fiber and waveguide devices.

We explore, by means of inelastic neutron scattering, the extent of changes in dynamic correlations induced by thermal poling of vitreous SiO2. The measured vibrational density of states shows an excess of modes in certain frequency regions as well as a narrowing of the 100 meV peak. These findings indicate that such alterations cannot be ascribed to the appearance of new well defined vibrational modes, such as those coming from localized topological defects, but rather arises from an increase in ordering in the material as attested in a reduced spread of the inter-tetrahedral angles.

A review of electro-optic and nonlinear optical devices based on poled glass will be presented, including recent developments and potential applications.