Measurement of charge density distributions in KTa_1-xNb_xO₃ optical beam deflectors

摘要

In a KTa1-xNbxO3 optical beam deflector, light rays are bent by a space charge formed by electrons that are injected through an electrode and captured by crystal defects. For complete device control, it is important to evaluate the space charge. We propose an optical method for measuring charge density distributions that utilizes the electrooptic (EO) effect of the material. With this method, electron accumulation caused by a screening effect was commonly observed near the cathode. The electron accumulation region extended toward the anode as the applied voltage and permittivity increased. This method can be applied to any EO materials that exhibit space charge distributions.