| Dielectric superlattice based on Quasi-phase matching (QPM) has a great application in the domain of nonlinear optics. Focusing on the fabrication of supperlatttice, this paper attempts to analysis the kinetics of ferroelectric domains in LiNbO3and LiTaO3using room temperature electrical poling method, find out the different poling characteristics of crystals with different components, and improve the technology of poling, create superlattice of LiNbO3and LiTaO3with high quality. A continues wave (CW) narrow linewidth yellow light laser source that can be used in laser guide star is set up by using periodically poled stoichiometric LiTaO3(PPSLT). The influence from illumination to the poling characteristics of MgO doped LiNbO3is explored and a new method of ultraviolet light assist poling is forwarded. The major contents are as follows:1. Based on the elementary nature of ferroelectrics, the distribution of electric field in LiNbO3and LiTaO3was studied. We describe the evolution of the distribution when periodically electric field is applied and propose the the model of domain kinetics of electrical poling at room temperature.2. After comparing properties of LiNbO3and LiTaO3with different components, we study their different poling conditions and succeed to fabricate domain structure in congruent LiNbO3, congruent LiTaO3; and stoichiometric LiTaO3with high quality. We improve the electrical poling method by the introduction of symmetric electrode on both sides of the substrate and do the trick in the experiment.3.We analysed the mechanisms that illumination influenced the poling properties of MgO:LiNbO3and compared the drop of coercive field when illuminated by different laser source. A new method to control domain conversion through the tailoring of light is proposed. And we aimd to fabricate MgO:LiNbO3supperlattice by realizing effect control of domain inverse in large area when suitable light source chosen.4. Random distribution of optical field was realized by scattering of ground glass. Stimulated by this random domain structure in MgO:LiNbO3substrate was fabricated and the mean domain size can be manual adjusted. Periodically poled MgO:LiNbO3was fabricated using light assistant poling.5. A10mm thick PPSLT sample with period of about lOum was fabricated and used as the frequency conversion crystal when pumped by a1178nm narrow linewidth Raman fiber amplifier. A4W CW589nm laser output was achieved with conversion efficiency14.3%and linewidth less than0.18GHz. The effect of light heating was studied. |
PDF Full Text Request