Time evolution of frozen-in field during poling of fiber with alloy electrodes.

Twin-hole fibers were provided with Au-Sn alloy electrodes and thermally poled at 255 degrees C. The evolution of the depletion layer was studied by etching fibers poled at varying poling temperatures. The electro-optic response was measured for different poling times. When the depletion region did not overlap the core the direction of the recorded field was opposite to the applied poling field. Poling for a longer time made the depletion region extend through the core and changed the sign of the recorded field.