Electrically Tuneable Optical Diffraction Gratings Based on a Polymer Scaffold Filled with a Nematic Liquid Crystal

Polymers

Irena Drevenšek-Olenik¹  Dejan Bošnjaković¹  Mathias Fleisch²  Xinzheng Zhang³ 

[1] Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia;Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria;International Sino-Slovenian Joint Research Center on Liquid Crystal Photonics, TEDA Institute of Applied Physics & School of Physics, Nankai University, Tianjin 300071, China;

关键词: nematic liquid crystals;    photoresist polymeric materials;    laser-based micro structuring;    diffractive optical elements;   

DOI  :  10.3390/polym13142292

来源: DOAJ

【 摘 要 】

We present an experimental and theoretical investigation of the optical diffractive properties of electrically tuneable optical transmission gratings assembled as stacks of periodic slices from a conventional nematic liquid crystal (E7) and a standard photoresist polymer (SU-8). The external electric field causes a twist-type reorientation of the LC molecules toward a perpendicular direction with respect to initial orientation. The associated field-induced modification of the director field is determined numerically and analytically by minimization of the Landau–de Gennes free energy. The optical diffraction properties of the associated periodically modulated structure are calculated numerically on the basis of rigorous coupled-wave analysis (RCWA). A comparison of experimental and theoretical results suggests that polymer slices provoke planar surface anchoring of the LC molecules with the inhomogeneous surface anchoring energy varying in the range 5–20 μJ/m². The investigated structures provide a versatile approach to fabricating LC-polymer-based electrically tuneable diffractive optical elements (DOEs).

【 授权许可】

Unknown