Dr. Inge Nys: Periodic Liquid Crystal Superstructures Stabilized by Patterned Anchoring
Liquid crystals (LCs) have the advantage that they can self-organize in complex structures and that they are strongly responsive to external stimuli such as an applied electric field. This makes them interesting for integration in tunable electro-optic devices such as diffraction gratings, lasers, light modulators and sensors. To develop new LC components and to optimize their functionality, it is essential to understand how the anchoring of the LC at the confining surfaces interacts with the elastic properties of the material. The LC director configuration in a confined geometry depends on a delicate balance between surface anchoring, elastic energy and, if an electric field is applied, dielectric energy. In my presentation I will discuss, based on some examples, how the combination of LC with periodically patterned surface anchoring gives rise to the formation of complex periodic superstructures. Both patterned photo-alignment and patterned surface topography in planar cells is tested to stabilize nematic and chiral nematic LC superstructures in the bulk. Also the effect of an applied electric field is studied in detail. Besides experimental work, numerical simulations are performed to get insight in the LC behavior and the optical properties of the devices. Applications of this research are mainly oriented towards diffraction gratings, smart windows, soft actuators and lasers.