Regensburg 2007 – wissenschaftliches Programm
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SYSE: Symposium Strain-Engineering for New Functional Structures
SYSE 2: Strain engineering in ferroics and photonics
SYSE 2.4: Hauptvortrag
Montag, 26. März 2007, 17:30–18:00, H1
Curl in Photonic Crystals Induced by Drying Stresses upon Sol-Gel Infiltration — •Vladimir Kitaev1, Evangellos Vekris2, and Geoffrey Ozin2 — 1Wilfrid Lauirer University, Waterloo, Ontario, Canada — 2University of Toronto, Toronto, Ontario, Canada
Colloidal photonic crystals will be introduced starting with monodisperse colloids and their self-assembly to structural control of the confinement. Recent results on curl control in inverse opal structures achieved by fine-tuning of the sol-gel infiltration process will be discussed. The driving force of structural transformations is the gradient in contraction arising from the drying stress between the sol-gel infiltrated into the porous media of the colloidal crystals and its surface overlayer. The curvature of the resulting assemblies can be consequently adjusted through the control of the overlayer thickness during the infiltration. Structural continuity (absence of cracks) is successfully achieved by optimization of the drying conditions. Optical characterization of curled photonic crystals using UV-vis microspectroscopy confirmed high structural quality of the template preserved and demonstrated that the stopband reflection of the curled colloidal photonic crystals can be described by the Bragg's law.