Tunable optical diffraction gratings based on a ferromagnetic liquid crystal
Mathias Fleisch, Faculty of Physics, University of Vienna, Austria
The director of a ferromagnetic liquid crystal can be realigned by small external magnetic fields. Transmission optical diffraction gratings composed of periodic slices of a ferromagnetic liquid crystal and a conventional photoresist polymer are demonstrated. Dependence of diffraction efficiencies of various diffraction orders on an in-plane external magnetic field is investigated. It is shown that diffraction properties can be effectively tuned by magnetic fields as low as a few mT. The experimental results are explained with analytical calculations based on the Jones calculus for polarising microscope measurements and simulations using the Rigorous Coupled Wave Analysis (RCWA) for the diffraction experiments.
S. Gao, M. Fleisch, R. A. Rupp, L. Cmok, P. Medle-Rupnik, A. Mertelj, D. Lisjak, X. Zhang, and I. Drevenšek-Olenik, “Magnetically tunable optical diffraction gratings based on a ferromagnetic liquid crystal,” Opt. Express 27 (2019)