Past colloquia and seminars


Ordered and disordered self-assembled photonic materials

General public Colloquium / Congress / Forum

Order is a good trait for many systems in science and technology because, among other benefits, it leads to easier analysis and description. In wave related problems, like photonic crystals, it leads to interference and can contribute to strengthening the signal from otherwise hardly detectable effects. This can make some spectroscopic techniques more powerful than others specifically developed like the case of adsorbate-detection where novel optical techniques based on Bragg diffraction in porous self-assembled materials can compete with usual isotherms.
In such cases, success relies on order but self-assembled structures are intrinsically disordered. It comes as no surprise that restraining disorder to improve performance will encounter many difficulties. Where surprise lurks is in the difficulty to produce disorder entirely averting order. A cunning way to achieve controlled disorder is by introducing it in order-maximized structured that profit from the best techniques developed to create self-assembled photonic crystals.
Such techniques permit to create vacancy-doped lattices where disorder can be introduced in any desired amount allowing so to study the effect on the optical properties. One surprising finding in these structures is the ability to control reflectance lineshape through a Fano-like effect that appears to reveal the greatest level of disorder occurring at the threshold for vacancy percolation.

When? 03.04.2019 17:15 - 18:15
Where? PER 08 0.51, bâtiment de Physique
Chemin du Musée 3
1700 Fribourg
speaker Prof. Dr. Cefe López
Materials Science Factory
Instituto de Ciencia de Materiales de Madrid (ICMM)
Consejo Superior de Investigaciones Científicas (CSIC)
Contact Prof. Dr. Frank Scheffold
chemin du Musée 3
1700 Fribourg
026 300 91 17 3