Chloe Tartan: In-Situ Structuring of Polymer Networks and Defects in Chiral Liquid Crystals for High Speed Photonics and Laser Devices
Datum objave: 17. 3. 2015
Seminar fizike mehkih snovi
Torek, 24. 3. 2015, ob 14h v Kuščerjevem seminarju, Jadranska 19, LjubljanaIn-Situ Structuring of Polymer Networks and Defects in Chiral Liquid Crystals for High Speed Photonics and Laser Devices
Chloe Tartan, University of Oxford, UK
In this presentation, we demonstrate how the formation of discrete polymer walls can be used to induce a uniform lying helix (ULH) alignment in a short pitch chiral nematic liquid crystal whereby the axis of the helix lies in the plane of the device. Under the application of an electric field perpendicular to the helix axis, an in-plane tilt is induced in the optical axis, which couples to the flexoelectric coefficients. The linear regime of the chiral flexo-electro-optic effect permits fast changes in the optical state leading to microsecond range response times in liquid crystals. Unfortunately, the ULH alignment becomes unstable when confined between spatially uniform aligning surfaces. Here we use a high resolution multiphoton absorption laser scanning lithography technique to form polymer walls of various dimensions and orientations relative to the rubbing of the alignment layers resulting in a spontaneous ULH alignment.