Dresden 2011 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 15: Poster 1: Quanteninformation, Quanteneffekte, Laserentwicklung, Laseranwendungen, Ultrakurze Pulse, Photonik
Q 15.19: Poster
Montag, 14. März 2011, 16:30–19:30, P1
Phase behaviour of electro-optic liquid crystals-oil blends — •Kirstin Bornhorst, Martin Blasl, and Florenta Costache — Fraunhofer Institut for Photonic Microsystems, Maria-Reiche-Str. 2, 01109 Dresden, Germany
New blends with high electro-optic (EO) constants are created by mixing the thermotropic liquid crystals 4-cyano-4*-n-alkylbiphenyle (nCB) with immersion oils. EO effect in blends occurs in their nematic as well as their isotropic phases. We study the optical, thermal and morphological changes of the new blends in view of possible applications for dynamic EO waveguides and compare them to pure nCBs.
The phase transition behaviour of pure n-CBs (n = 4-7) and nCB-oil blends was analysed as a function of oil concentration by DSC and their corresponding changes in morphology with polarized optical microscopy. For all blends we observed that the nematic-isotrop transition temperature, TNI, as well as the crystalline-nematic transition temperature, TCN, shift largely toward lower temperatures with increasing oil concentration. For instance, TNI in the 5CB-oil blend was found to be 17 ∘C lower than that of pure 5CB. Additionally, we observed significant texture changes in the blends.
The isotropic phase for 5CB- and 6CB-oil blends occurs at room temperature. Interestingly, the nematic phase of 5CB-oil blend exists over a much wider temperature range as compared to that of pure 5CB. We will show that this can considerably help the temperature stabilization requirements of the EO waveguide device.