21 February 2014

COBRA COLLOQUIUM: Friday February 21, 2014 at 15:00 – 16:00 in the Film Theater of Grand Café and Film house De Zwarte Doos

Speaker: Prof. T.D. Wilkinson

Title: Towards liquid crystal nanophotonic devices

Abstract: Advances in nanoscale fabrication allow for the realization of artificial materials with properties that do not exist in nature, metamaterials. They are composed of subwavelength electromagnetic structures, placed at close proximity to each other. Due to mutual coupling between individual structures, they present properties to incident electromagnetic radiation that are different from those associated with the material from which the structures are comprised of. We have reported the use of multiwalled carbon nanotubes (MWCNTs) and silver nano-rods, as subwavelength structures to produce optical metamaterials that exhibit artificial dielectric properties, wavelength and polarisation control and band gaps within the optical regime. If a liquid crystal (LC) material is added to this geometry it provides a variable refractive index pathway between the CNTs and alters the plasmonic frequency in a complex way. This is not a simple process to model or measure as the interaction at the surface of the CNT with the liquid crystal has a dominant effect in this geometry and is very difficult to observe experimentally, however the addition of the LC materials allow us to electrically tune the properties of the metamaterials

Biography: Prof. Wilkinson has had a long term research interest into the applications of liquid crystal (LC) devices, holograms, nanophotonics and related applications. One breakthrough made recently was in algorithms which lead to the commercialisation of holographic projectors. The use of holograms has also been used for telecoms to demonstrate modal control and full mode characterisation in multimode fibres. Core to his research has been liquid crystal device fabrication and the search for the optimal materials for different applications. One of the holy grails that has eluded us so far is the fast elector-optical effect suitable to modulate the phase of the light at rates < 1mSec. My research has pioneered hybrid LC/CNT (carbon nanotube) technology including design and fabrication of plasmonic optical filters, waveguides, resonators and super-resolution lenses. We have also demonstrated that these structures can be made reconfigurable using LC materials. Most recently new devices and electro-optics have been demonstrated using graphene and LC/graphene materials.

After the colloquium (around 16:00) we organize a mini-colloquium in which three COBRA researchers, one from each of the three COBRA groups, will give a short presentation about his or her work.

For the Electro Optical Communication Group:
Speaker: Joanne Oh                Title: Simultaneous 1.5 Gbps Multilink Indoor Optical Wireless System Using Diffractive Optics
For the Photonic Integration Group:
Speaker: Kasia Lawniczuk       Title: AWG-laser based transmitter with DBR mirrors and Mach-Zehnder modulators
For the Photonics and Semiconductor Nanophysics Group:
Speaker: Francesco Pagliano   Title: Ultrafast Electrical Modulation of the Exciton Energy for the Dynamic Control of Cavity Quantum Electrodynamics

The audience is invited to an informal gathering following the colloquium (around 17:00) in the lounge of Grand Café and Film house De Zwarte Doos.