The theory of correcting the devation of retardation of wave-plate

In order to get the information of index of refraction,we measure the properties of birefringence of LiNbO3and LiNbO3 waveguide,using UT300-FPD ellipsometry.Firstly,we made model of LiNbO3 and fit the results,so we have the index of refraction from 190nm~1700nm.Secondly,based on the model of the first step,we readily obtain the model of LiNbO3 waveguide and the distribution of the index of refraction.The work we have done provide useful information for the development of LiNbO3 waveguide as photon devices.