Research On Fabrication Techniques Of Optical Superlattice

Optical superlattices based on quasi-phase matching technology are widely used in laser nonlinear frequency conversion and quantum information technology.The preparation process has always been the research content of people’s attention.In this paper,aiming at technical problems such as small period and magnesium-doped lithium niobate optical superlattice electric field poling,on the basis of introducing the structural characteristics of lithium tantalate and lithium niobate,as well as understanding the dynamics of domain flipping,explored the double-sided electrode electric field poling,Technical solutions such as high-temperature electric field poling and insulating layerassisted room-temperature electric field poling have realized the successful preparation of small-period optical superlattices and doped magnesium lithium niobate optical superlattices.Specifically include the following aspects:1.Starting from the basic characteristics of lithium tantalate and lithium niobate crystals,the domain dynamics model in the room temperature electric field poling process is introduced.Based on this,the preparation of large-period optical superlattices is prepared,and the differences are compared.The influence of the electrode material on the electric field poling result.2.The principle of over-electric field poling technology was explored,and on this basis,a double-sided electrode electric field poling scheme was proposed,and onedimensional and two-dimensional lithium tantalate optical superlattices with a small period(5μm)were prepared,with good domain penetration,The positive and negative domain patterns are basically the same.3.In view of the electric field poling technology problems of magnesium-doped lithium niobate,several technical solutions have been tried.Taking advantage of the coercive field reduction characteristics of magnesium-doped lithium niobate at high temperatures,an optical superlattice of magnesium-doped lithium niobate with a thickness of 1 mm and a period of about 30 μm was prepared.Using Si O2 as an insulating layer,combined with multi-pulse electric field poling,an optical superlattice with a thickness of 0.5 mm in magnesium-doped lithium niobate was prepared at room temperature with a period of more than ten microns.In addition,we also tried other technical solutions for preparing magnesium-doped lithium niobate superlattices at room temperature,including ultraviolet light-assisted electric field poling,electric field poling after proton exchange,etc.,and obtained preliminary results.