Electro-optic modulation in germanosilicate fibrewith UV-excited poling

Abstract
The authors report what is, to their knowledge, the highest electro-optic effect measured in a germanosilicate fibre ever reported. The electro-optic effect based on a permanent second-order nonlinearity has been induced by UV-excited poling at 193 nm with an electric field > 8 × 105 V/cm. Polarisation dependence of the VπL product in a birefringent fibre has been observed, and the lowest VπL product obtained for the TE mode of 32 Vcm, comparable to that based on r22 of LiNbO3, has been measured at 633 nm with a phase modulation at frequencies up to 5 MHz.