Periodically-poled KTP Crystal Fabrication And Characterization Of Second Harmonic Generation Reseach

This work is supported by national Nature Science Foundation. In this dissertation, quasi-phase-matched technology is researched in theoretical ways. The properties and analysis of periodically poling of KTP crystal are obtained through experimental research. Investigation on the theory and technique of domain inversing is the basis of fabrication of KTP with ideal inversed domain structures. The focus of this dissertation is to develop strategies for the fabrication of PPKTP through investigating the electric field periodic poling process in KTP, and to improve the quality of domain-reversal processes through identifying and optimizing those parameters contributing most significantly to the quality of KTP. Major contributions are as follows:1. quasi-phase-matched technology is researched in theoretical ways. The major concepts, such as spontaneous polarization, pyroelectric effect, piezoelectricity etc.,are described.2. A new type of poling voltage waveform for the fabrication of Periodically Poled KTP by electric field poling method was presented and the related high voltage power supply was designed .This power supply can output trapezoid waveform, periodic square waveform and others generated by these two waveforms.3. The domain switching process and characteristics of periodically poled KTP was analyzed, and based on which important factors in fabrication such as choosing electrode and the design of poling waveforms are identified. These analyses provide the basis for the development of poling methods.High voltage used together with low voltage has been utilized.4. The work shows that the in-situ SHG technique used together with electro-optic monitoring, makes it possible to obtain reliable, real-time information regarding the poling quality over the whole crystal aperture during the electric-field poling process. Uniform and fan structure periodically poled KTP crystals are successfully fabricated by using of liquid electrode scheme in external electrical field poling method.5. The confocal cavity a used in SHG are analysized and optimizing condition is discussed. The SHG output of self-made PPKTP reached 70mW at 532nm which is the best in present reported results and the conversion efficiency was 8.7%. The calculated single-passed normalized conversion efficiency was 1.69%/W·cm. As we known, there is no other similar achievement reported in China.