Fabrication And Investigation Of Micron-scale Ferroelectric Domain Of Lithium Niobate

Lithium niobate is an excellent synthetic crystal.It has stable mechanical properties,the capacity of high temperature resistant and corrosion prevention.The crystal can be growth easily and has a low price.And lithium niobate is also a multi-functional material which has a serious of properties such as acoustic-optics, pizoelectronics and nonlinear optics,and it has the biggest nonlinear optical coefficients in inorganic materials.Through change the orientation of ferroelectric domains of lithium niobate periodically to make periodic poled lithium niobate(PPLN) is widely used in several aspects,such as second harmonic generation of laser,optical parametric oscillation and optical waveguide and so on.The main research direction of this thesis is explore the fabrication technique of micro domain structure of lithium niobate,and it primarily contains the following two aspects:1. A set of experimental system which use the technique by apply high voltage to pinpoint has been put up to fabrication domain structure of lithium niobate.We designed the related mechanical structures of this instrument,such as the structures of micro-motion platform,suppot and adjusting system of platform, the observing device of the pinpoint,sample stage,etc.We also built the motion control system of the experimental facilities,use the GALIL controller to control micro-motion platform and high voltage pulse source,and developed some relevant PC side control program.2. We made some experiments for tailoring point-like and strip-like domains in lithium niobate crystal in different conditions.We observed the domain non-destructive by use polarization microscopy and get pictures of domain through the USB image acquisition device. We compared the influence of the magnitude of applied voltage,movement speed and duration of applied voltage on the size of domain,We can come to a conclusion that the size of domain is proportional to the magnitude and duration of applied voltage and inverse proportional to domain processing speed. At last, we contrasted the experimental image of polarization microscopy with hydrofluoric acid etch patterns.