Date
Place
- Room G (Room 306)
- 47. Optical Properties of LC
- August 21, 2015 (Friday)
- 09:00 ~ 10:30
- [47-1]
- 09:00 ~ 09:25
- Title:[Invited] Electro-Optics and Dielectric Measurements in Polymer-Stabilized Liquid Crystals of High Chirality
- Alexander Lorenz (Technische Universitat Berlin, Germany)
Abstract: Fast electro-optic switching in both hyper-twisted chiral nematic (N*) LCs and blue phase (BP) LCs is presented. Response times well below 500 ¥ìs were observed in both types of LCs, respectively. Structural stabilization of the LCs was provided with fitted cross-linked polymers. Polymer was in-situ generated: Mass-ratios of up to 10% of reactive component (a photo-reactive mixture of reactive mesogens, acrylates, and photo initiator) were added to the LCs, respectively, and exposed with a controlled dose of UV radiation. Mass-ratio and composition of reactive component had great influence on the resulting electro-optic properties of the LCs. In N* LCs, polymer-stabilization was found to effectively suppress unwanted textural transitions especially near the interdigitated addressing electrodes. Simulations of the electric field-distribution inside the test cells were carried out: The local distribution of induced birefringence was successfully modeled. The electro-optic response was mainly caused by the flexoelectro-optic effect at low voltages and by the Kerr effect at high voltages. Polymer-stabilized BP LCs were generated in reflective test cells. A double-slit diffraction experiment revealed continuous, polarization-independent optical phase modulation in the BP LC layer. The magnitude of the induced birefringence could be enhanced by 20% in test cells with larger platelets.?
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