Activation energy of DC-drift of x-cut LiNbO3 optical intensity modulators

The DC-bias-induced drift phenomenon in LiNbO/sub 3/ optical intensity modulators is a main cause of device wearout failure. In order to estimate the device lifetime, an activation energy value Ea of the drift is needed, and Ea=1.0 eV is already known for z-cut LiNbO/sub 3/ modulators. However, Ea of x-cut LiNbO/sub 3/ modulators is not known even though there is a possibility that the Ea depends on the crystal orientation. Here, Ea=1.4 eV is obtained experimentally for the x-cut LiNbO/sub 3/ modulator with a SiO/sub 2/ buffer layer from their drift measurements between 50/spl deg/C-140/spl deg/C.