Thermally stimulated poling and depoling current in thermally poled silica fiber

This paper presents an analysis and comparison of the poling and depoling current evolution with the electro-optic coefficient evolution for positively poled twin-hole fiber, where the anode is closer to the core. The current discharge efficiency was measured to be 5% suggesting that the poling mechanism is due to movement of space charge. During thermal poling we have observed a current peak which corresponds to formation of the shielding field. After formation of the shielding field the electro-optic coefficient begins to grow due to a second poling mechanism. The second poling mechanism occurs during the decay component of the current evolution. The second poling mechanism causes the depletion region to move into the fiber and obtain better overlap with the core. The activation energy for charges in the current peak are of the order of 0.5 eV. In addition, the activation energy was measured to be 30% higher for depoling than for poling of the same device.