Fabrication And Third-Order Nonlinear Optical Property Of Prophyrin/Polyoxometlate/Layered Double Hydroxide Systems

Porphyrin with a large nonlinear optical coefficient, good stability and modifiability, had got people’s attention in the field of nonlinear optics. Further improve the nonlinearity of porphyrin and fabricate porphyrin nonlinear device for their practical application is important. In this thesis, porphyrin/LDH films, porphyrin/POM/LDH films and porphyrin/POM/LDH cointercalation compounds were prepared by layer-by-layer assembly and exfoliation-retacking with meso-tetrakis(p-carboxyphenyl)porphyrin, Preyss-ler-type polyoxometalate (POM) and MgAl layered double hydroxide (LDH), respectively. And the third-order nonlinear optical property of these materials were characterized by Z-scan with nanosecond laser pulses. The main results are as follows.(1) Porphyrin/LDH films were fabricated regularly, the surface of which were uniform and smooth. They exhibited a saturable absorbtion property and self-defocus behavior under the effect of strong light. The nonlinear absorption property of the films were in contrast with porphyrin solution, which could be attributed to the surface state capture effect. The nonlinear effect of the films became larger with the increase of the number of bilayers. For the film with 50 bilayers, x(3)= 6.4×10-11 esu. Porphyrin/LDH films showed larger nonlinear property than porphyrin solution when the number of bilayers was not too low, which was due to the higher concentration of porphyrin in the films.(2) Porphyrin/POM/LDH films were fabricated uniformly, the surface was flat and smooth. These films exhibited saturable absorbtion property and self-defocus behavior. The nonlinear effect of the films became larger with the increase of the number of bilayers. The porphyrin/POM/LDH films showed higher nonlinear optical porperty than prophyrin/LDH films with the same content of porphyrin and the same number of bilayers. The χ(3) of porphyrin/polyoxometalate/layered double hydroxide film with 20 bilayers was 1.67 times that of the corresponding porphyrin/LDH film. It may result from the donor-acceptor interaction between porphyrin and POM in different layers.(3) Each of porphyrin/POM/LDH cointercalation compounds was a single crystalline phase. The ratio of POM and porphyrin in the interlayer changed with the ratio of POM and porphyrin in the solution changed. These cointercalation compounds had reverse saturated absorption property and self-defocus behavior. When the concentration of porphyrin was the same in the suspension of cointercalation compounds, the nonlinear effect of suspensions increased with the ratio of POM and porphyrin in the interlayer increased. The donor-acceptor interaction of POM and porphyrin was considered to enhance the nonlinear effect of porphyrin in the interlays.