Birefringence Grating and Surface Grating in Azobenzene Polymer Liquid Crystal Films Investigated by Near-Field Optical Method
ZHANG Jiang-Ying1, MING Hai1, WANG Pei1, SUN Xiao-Hong1, LU Yong-Hua1, WU Yun-Xia1, XIE Jian-Ping1, ZHANG Qi-Jin2,3, LIU Jian2,3, XIE Ai-Fang4, ZHANG Ze-Bo4, GU Ben-Yuan4
1Department of Physics, University of Science and Technology of China, Hefei 230026
2Structure Research Laboratory, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026
3Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026
4Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080
Birefringence Grating and Surface Grating in Azobenzene Polymer Liquid Crystal Films Investigated by Near-Field Optical Method
1Department of Physics, University of Science and Technology of China, Hefei 230026
2Structure Research Laboratory, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026
3Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026
4Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080
Abstract： The birefringence grating and the surface grating in azobenzene polymer liquid-crystal (Azo-PLC) films are studied by a near-field scanning optical microscope. With laser irradiation, the refractive index change caused by birefringence and the sinusoidal surface profile are observed at the near-field transmittance image and the surface topography of the grating. The grating period and the peak-to-peak value of the sinusoidal surface profile are 0.8μm and 40 nm, respectively. The maximum diffractive efficiency of the grating is 2%. The dynamic process of the grating formation is probed and analysed. The mass diffusion responsible for the formation of the surface grating due to the temperature rise is analysed.
2003, Vol. 20 
