Space-selectively crystallized fiber with second-order optical nonlinearity for variable optical attenuation.

We have fabricated BaO-TiO2-GeO2-SiO2-based glass fibers with the oriented space-selectively crystallized structure by laser irradiation and also demonstrated variable optical attenuation induced by electro-optical birefringence change based on second-order optical nonlinearity. The transmittance of a polarized signal is controlled by an electric field applied to the fiber, and the electro-optic fiber devices are operated with extremely low nanowatt electric power dissipation.