| In recent years, in the research areas of nonlinear optical material, in order to overcome inherent weaknesses of a single inorganic and organic material, people naturally think of making use of the advantages of both and synthesize nonlinear optical hybrid material. There is a direction of seeking new nonlinear optical material which new POM structure compounds can be synthesized which have properties of both organic compounds and POM and Various organic groups, Metal Complexes and polyoxometallate as the basic building unit can be synthesized into hybrid polymers which have multidimensional holes structure.Polyoxometallate molecules and substrate molecule framework produce some new features which individual components don't have by synergistic effect between the components in addition to the respective specific physical properties. Firstly, This paper introduces the method of measuring third-order nonlinear optical coefficient, including the four-wave mixing method, time-resolved optical Kerr effect method, Z-scan method, non-linear interference method and so on, and characteristics and development of organic-inorganic hybrid nonlinear optical material, especially polyoxometallate.Secondly, the paper describes several common Z-scan methods and then deduces Gaussian decomposition theoretical model for Z-scan with nonlinear absorption and without nonlinear absorption in detail. Details and attentions for adjusting Z-scan light path are given. By using C60 sample, Z-scan experimental system is tested in the condition of open-aperture and close-aperture. Optical limiting experiment of C60 sample is also tested.Finally, the paper introduces to preparing supermolecular compound sample by means of hydrothermal synthesis method. It reports how to study on nonlinear optical properties of the following four POM samples and their experiment results by means of Z-scan method under conditions of wavelength of 532 nm and 8 ns pulse.(1) Compound 1: Supermolecular based on POM: (HDPA·DMF)2(HDPA·2DMF)(PMo12O40);(2) Compound 2: Keplerate spheroidal nanoporous POM 1:(NH4)72- n [{(H2O)81-n+ (NH4)n )}(?){(MoⅥ)Mo5ⅥO21(H2O)4}12{Mo2ⅤO4-(SO4)}30]·ca.200H2O (3) Compound 3: Keplerate spheroidal nanoporous POM 2: (NH4)31(NH2CHNH2)6Gd1[{(NH2CHNH2)20+Gd4}{(MoⅥ)Mo5ⅥO21(H2O)6}12{ Mo2V-O4(SO4)}30]·ca.260H2O(4) Compound 4: Bielefeld giant-wheel nanoporous POM Na15[Mo126ⅥMo28ⅤO462H14(H2O)70]0.5[Mo124ⅥMo28ⅤO457H14(H2O)68]0.5·ca.400 H2O.Under the corresponding theoretical model numerical simulation results are given for the experimental results. The influence of the molecular structure of polyoxometallate sample to the third-order nonlinear optical properties is discussed. The results show that these POM samples haven't significant nonlinear absorption properties, but they have negative and much larger third-order optical nonlinear refractive index and characteristics of a self-defocusing.The results of this paper which contribute to enhance third-order nonlinear optical coefficient have very important significance for molecular design of nonlinear optical material. |
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