Orientation-Enhanced Photorefractive Effect in PVK-PBA:DR1:TNF Polymer
LI Lu-Ying1, ZHAO You-Yuan1, LI Fu-Ming1, YANG Jian2, CHEN Guo-Rong2, WANG Chang-Chun3
1State Key Laboratory for Advanced Photonic Materials and Devices, Department of Optical Science and Engineering, Fudan University, Shanghai 200433
2Department of Material Science and Engineering, Fudan University, Shanghai 200433
3Department of Macromolecule Science, Fudan University, Shanghai 200433
Orientation-Enhanced Photorefractive Effect in PVK-PBA:DR1:TNF Polymer
LI Lu-Ying1;ZHAO You-Yuan1;LI Fu-Ming1;YANG Jian2;CHEN Guo-Rong2;WANG Chang-Chun3
1State Key Laboratory for Advanced Photonic Materials and Devices, Department of Optical Science and Engineering, Fudan University, Shanghai 200433
2Department of Material Science and Engineering, Fudan University, Shanghai 200433
3Department of Macromolecule Science, Fudan University, Shanghai 200433
Abstract： We developed a novel photorefractive (PR) polymer PVK-PBA:DR1:TNF, and its film sample was prepared with outstanding performance by using the method of combination of vacuum saturated vapour resolving with vacuum hot-pressing. The sample exhibits distinctive PR properties with the two-beam coupling coefficient up to 140cm-1 and four-wave mixing (FWM) diffraction efficiency above 1.5% in the absence of applied external electric field. The designed experiments, including measurements of the second-order nonlinear coefficient and birefringence as well as the relationship between the diffraction efficiencies of the FWM and the external bias field, were performed to understand the underlying mechanism, because this phenomenon cannot be explained by the conventional PR theories. It is presented that because of its high orientational mobility and large dipole moment, the polymer produces the photovoltaic effect under the irradiation of laser to induce a space-charge field so as to engender the PR effect under zero or low external fields. A model based on the assumption was established and the simulation agrees well with the experimental results.
2004, Vol. 21 
