The polyimide can fully meet the requirements of the nonlinear optical material as the material. As one of the main obstacles is the optical loss optical materials, polyimide optical loss mainly from the following aspects:
1. By the charge transfer effect polyimide macromolecules present in the generated light absorption.
2. The light scattering polyimide by solvent evaporation or cyclization to produce evaporation of water in the polymer leaving the hole caused by the thermal cyclization of polyamic acid is formed.
3. The density of the formed polymer is present in the different domains fluctuations caused by light scattering.
4. from the outside into the light scattering caused by impurities and the like.