Fabrication And Application Of Periodic Poled Lithium Niobate

Lithium niobate crystal has a serious of outstanding properties of electro-optics, acoustic-optics, plastic-optics, pizoelectronics,pyroelectricity and nonlinear optics, which make it one of the most attractive materials for acoustic-optical, electro-optical and nonlinear optical devices. Periodic poled lithium biobate (PPLN) based on quasi-phase matching (QPM) technique uses the largest nonlinear coefficient of lithium niobate d33(25.2pm/V), and is widely used in parametric process, such as second harmonic generation, differential frequency generation, optical parametric oscillation, in THz wave generation, and is an promising technique in the field of optical communication, especially in wavelength conversion and all-optical switching.We emphasized our study on the basis of domain reversion of PPLN, roughly solving substantial problems of poling process, optimizing poling process, and building an well-developed platform readily for further improvements of the quality of PPLN device. The work integrated theoretical analysis and experimental evidence, and its major contribution is listed as follows:1. The electric field distribution of poling structure is analyzed with finite element method. A comparison is made between comb-like and frame-like electrode structure. A novel periodic poling electrode structure which efficiently decreases the fringe field and is suitable for the poling of crystal with a small dimension is proposed based on theoretical analysis. This structure is applied for an invention patent. (application no.: 200510015505.6).2. The influence of several potential defects on the poling process is systematically analyzed, which includes the residual bubble issue of liquid electrode method with an countermeasure proposed; the interaction of different parts when multiple period is simultaneously poled; the influence of small protrusion and broken strip on poling process.3. Five important geometric parameters in periodic poled lithium niobate, permittivity of insulator, thickness of insulator, width of electrode, applied voltage and period, are numerically analyzed with a computational model from Stanford university. A general procedure in the design of poling configuration is thus obtained. The square regression formula for the relationship of width of electrode versus period achieved here will be an useful assistant of the design process.4. Corrects the synthesized tuning curve from an important reference, and points out the major algorithm mistake.5. An 3-D kinetic model which demonstrates the poling process precisely is presented.6. Study the break-down characteristics of lithium niobate which is intrinsicly related to the poling process.7. A practical jig used for liquid electrode method is designed, and the high voltage supplier is revised for higher performance.8. A 20mm-long PPLN is fabricated and characterized for the first order second harmonic generation of 1064nm continuous wave Nd:YVO4 laser. A 20.55mW green light of second harmonic is obtained when the pump power is 1.51W. The corresponding conversion efficiency is 1.36%, which improves 26 times than our early results, and reaches the average of domestic research under the same condition.