Study On The Fabrication Of Surface Domain Inversion Structures In LiNbO₃

Lithium niobate(LiNbO3)crystal is a kind of artificial material widely used in the electronics and optoelectronic industry.We have achieved a series of applications using LiNbO3 based on its piezoelectric,ferroelectric,electro-optical and nonlinear optical properties.One of its most widely used applications is the preparation of surface acous-tic wave devices,which are widely used in mobile phones and other wireless terminal products.Since the lithium niobate crystal have excellent electro-optical characteristics,a lithium niobate electro-optic modulator and as many core materials it is also widely used in the field of optical communications.At present,the nonlinear optical proper-ties of lithium niobate are also increasingly used in wavelength conversion and other fields,the development of lithium niobate periodic polarization technology to promote the laser wavelength conversion,optical parametric oscillator,optical signal processor A series of results.We all know that the applications of lithium niobate in nonlinear optics need to meet the phase matching conditions,Quasi phase matching technology is widely used is the current phase matching technology.Quasi-phase matching is achieved by lithium niobate’s domain engineering,where the domain inversion structure is generated by periodic polarization.The current lithium niobate domain inversion process is most widely applied electric field polarization,optical Induced been much attention in recent years.In this thesis,we mainly study the domain inversion process of lithium niobate using high voltage tip polarization method.We design an automatic device for domain structure preparation based on the method of high voltage tip polarization.Aiming at the conditions of different polarization voltage and high voltage pulse duty cycle,we con-duct comparative experiment to arrive at the best experimental conditions.The samples used in our experiments are 0.5 mm thick z-cut 5.0 mol%Mg doped lithium niobate crystals,in the experiment we preparate the dot-shape domain and line-shape domain,and finally we arrive at the best experimental conditions.When the polarization volt-age is controlled at 2.6 kV～2.8 kV,the regular hexagonal dot-shape domain inversion structure can be prepared.When the polarization voltage is controlled at about 2.7 kV,the high duty pulse duty cycle is 25%and the scanning speed is 15 μm/s,a more uni-form line-shape domain inversion structure can be prepared.In addition,we also use the external electric field polarization method to preparate line-shape domain structure and explore the optimum experimental conditions of external electric field polarization method.