Fluorine and sodium depletion followed by refractive index modification imprinted on fluorophosphate glass surface by thermal poling

Thermal poling using microstructured electrodes on oxyfluoride glasses have been investigated and the impact on optical properties is evaluated. A micrometer refractive index modification based on the sodium and fluorine migration have been evidenced, creating a layer with different chemical composition compared to the original glass. Topological and optical properties modifications after poling treatment are discussed. For the first time, we described the migration of negative fluorine ion in the direction of the cathode from the glass network. Na and F migration led to a layer richer in oxides with a strong contrast of + 0.06 of the refractive index in the imprinted structures.