When: September 05, 16:00
Where: Skoltech, MR-408 (TROC-3, Blue building)
Seminar:
Tailoring the mode distribution in dielectric resonant structures
Prof. Dr. Thomas Kusserow
Technical University Darmstadt
Institute for Microwave Engineering and Photonics (IMP)
Abstract:
Periodic thin-film structures are widely used as resonant elements since many years, in the form of highly reflecting mirrors, narrowband spectral filters or polarizers. But still many interesting research topics can be found if these rather simple structures are varied or applied in new ways.
In the first part of my talk, narrowband resonant structures based on thin-films with slightly varying periodicity (chirped layers) will be presented. By distributing the cavity of a Fabry-Pérot filter over the whole thin-film structure a similar resonance can be obtained without any discrete cavity layer. This approach provides new design parameters for narrow-band filters, but especially can be used to control the distribution of the electric field of the resonant mode in the whole structure. After some initial discussion of the properties of these structures, the development of a VCSEL device based on chirped layers with colloidal quantum dots as emitter material will be shown.
The second part of the presentation will focus on Bloch surface modes on 1D periodic structures. Light can be localized on the surface of a highly reflecting thin-film structure if a mode is fulfilling the condition for total internal reflection to prevent free space propagation and has a frequency in the stop-band of the periodic structure at the same time. The behavior is similar to surface plasmon-polariton modes, but can be realized with dielectric materials rather than with metals. When coating the surface with another material, the localized surface mode can be used to enhance emission or absorption effects. An overview of the basic properties and first experimental results will be shown.
BIO:
Thomas Kusserow received a Diploma in optical engineering (2002, Cologne) and the MSc degree in Photonics (2004, Göttingen). He worked at the Institute for Nanostructure Technologies and Analytics (INA), University of Kassel, from 2005 on and received his PhD in 2010. Since 2014 he is assistant professor at INA (Kassel), heading the nanophotonics group. From 2018 on he also is professor at TU Darmstadt in the field of optical communication and photonics. His main research interests are focused on optics of resonant structures and modification of optical material properties.