Study Of Electro-optic Effect Of Orthogonal Phase Tantalum Potassium Niobate Crystal

Potassium tantalum niobate(KTa1-x Nbx O3,KTN)crystals have been extensively studied by researchers because of their excellent electro-optical properties and the advantages of no pollution to the environment.KTN crystal is a multifunctional photoelectric functional material that can be used in the preparation of optical devices.Due to its excellent properties,the study of KTN ferroelectric single crystals is very extensive,especially for the properties near the tetragonal-cubic phase transition temperature,and there is a lack of relevant research on the electro-optic properties of KTN crystals in the orthogonal phase.Therefore,in this paper,the electro-optic performance of orthogonal phase KTN is studied experimentally and theoretically,and the effect of external electric field on the refractive index is analyzed.The physical properties of KTN crystal were experimentally characterized.In order to characterize its structure,the structure of KTN crystal was characterized by X-ray diffraction method,so as to obtain the crystal phase and lattice constant.The response relationship between the temperature of the KTN single crystal and the relative dielectric constant was measured through experiments.Due to the peak of the dielectric anomaly pattern,the phase transition temperature was determined,and the relative dielectric constant and crystal composition corresponding to different temperatures were calculated.The domain structure of ferroelectric single crystal was characterized by piezoelectric power microscope(PFM),and the sub-micron domain structure in orthogonal phase KTN crystal was obtained,which provided a certain theoretical basis for the analysis of electrooptic performance.The electro-optic effect of orthogonal phase KTN crystal was studied.The change of the polarization intensity of KTN crystal with the external field is measured,and the relevant parameters are obtained,which provides a basis for the polarization experiment and the theoretical calculation of the electro-optic performance.The polarization conditions of orthogonal phase KTN crystal were explored by changing the variables such as applied electric field,polarization duration and polarization temperature,and the optimal polarization conditions were determined,and the completed samples were used for experimental measurement.According to the theory of light propagation in the crystal,the change trend of the photometric body of the ferroelectric single crystal with 2mm point group symmetry with the applied electric field was calculated.The Mach-Zehnder double-beam interference system was built to measure the linear electro-optic coefficient of the KTN sample.The electro-optic coefficient of the orthogonal phase KTN crystal is about 10-10 m/V.In theory,the electro-optic matrix of the orthogonal phase KTN crystal is calculated.In theory,the method of calculating the conductive light matrix through the calculation of the secondary auroral coefficient is introduced,and the linear electro-optic coefficient of the orthogonal phase and the tetragonal phase is deduced by using the secondary auroral g coefficient to obtain the KTN ferroelectricity in different phases.The linear electro-optic coefficient of the crystal is directly proportional to the spontaneous polarization of the sample.The electro-optic effect essentially means that the refractive index will change with the external field.Using MATLAB calculation to simulate the electric field in different directions,the refractive index ellipsoid of the orthogonal phase KTN single crystal changes,and the calculation results are analyzed to obtain external field conditions when a large electro-optic coefficient is obtained under different conditions.