Optical Nonlinearity Enhancement in Cross-Linked Polydiacetylene (PDA) Supramolecules Composited with Nanometer-Size Silver

Polydiacetylene (PDA) vesicles with various cross-linking degree were prepared by adding different quantity of ethylenediamine. Ag nanoparticles were added into above systems to form the cross-linked PDA/Ag composite vesicles. UV-vis spectra and transmission electron microscopy (TEM) were used to confirm the formation of the cross-linked PDA/Ag composite vesicles. Their thirdorder nonlinear optical (NLO) properties were investigated in detail. A pronounced enhancement of the third-order nonlinear optical susceptibility χ(3) was observed with increasing of the cross-linking degree, which should be ascribed to the coupling effect of strong local field near the adjacent PDA/Ag composite vesicles.