past events

Thursday 31. March 2016

IMPRS monthly meeting

 

Organisation: Hsuan-Wei Liu (MPL/ Sandoghdar Division)

Talk: Spontaneous emission control in hybrid photonics systems

Speaker: Dr. Martin Frimmer (Photonics laboratory, Dept. of Information Technology and Electrical Engineering, ETH Zürich)

Place: MPL / Large seminar room (*429/435)

Abstract:

Nanophotonics is the science of controlling all aspects of light generation, propagation, and absorption on length scales smaller than the wavelength. This talk focuses on controlling the spontaneous emission of photons. The quantity of paramount importance in the context of spontaneous emission control is the local density of optical states which can be engineered by designing the electromagnetic environment of the source. After reviewing the established nanophotonic tools for spontaneous emission control, we turn to hybrid photonic systems harnessing the sometimes counter-intuitive electromagnetic interplay between several building blocks.

Thursday 25. February 2016

IMPRS monthly meeting

 

Organisation: Sebastian Käppler (FAU/ Pattern Recognition Lab)

Talk: Physics-based and statistical features for detecting image manipulations

Speaker: Dr. Christian Riess (FAU)

Place: MPL / Large seminar room (*429/435)

Abstract:

Digital images are now captured anywhere, anywhen, by anyone. For several businesses, e.g., media networks and insurance companies, it is crucial to know whether an image is original, i.e., proof for an event, or manipulated.
In this talk, we will review landmark methods for determining authenticity of an image, including work performed at our lab.

Monday 25. January 2016

IMPRS monthly meeting

 

Organisation: Sivaraman Subramanian (MPL/ Vollmer Lab)

Talk: Conformational Dynamics of Single Enzymes and Biomolecules

Speaker: Dr. Michael Schlierf (Center for Molecular Bioengineering, TU Dresden)

Place: MPL / Seminar room, building 26 (*408)

Abstract:

Over the past decade, numerous single-molecule techniques have become available to study biological molecules. In particular, the observation of conformational changes within these biomolecules or during interactions have become directly accessible. Here, I will present how we develop and apply single-molecule techniques to characterize molecular machines. I will introduce farFRET, a technique to observe large conformational changes, and how we use single-molecule FRET to study membrane protein folding and protein-DNA interactions.

Monday 18. January 2016

IMPRS soft skill course
"Career Building"

 

Teacher: Dr Dennis Fink (mediomix)

Place: Large seminar room of MPL (*429/435)

Participation: Only registered IMPRS students

Thursday 03. December 2015

IMPRS alumni talk

 

Talk about "real life" experiences by: Dr Marta Ziemienczuk (former IMPRS PhD student in Russell Division)

Place: MPL / Large seminar room (*435)

Thursday 03. December 2015

IMPRS monthly meeting

 

Organisation: Martin Finger (MPL/ Russell Division)

Talk: Optical manipulation of biological cells using ultrashort laser pulses and plasmonic gold nanoparticles

Speaker: Dr Maria Leilani Torres (Institute for Quantum Optics, Biomedical Optics Group, Leibniz University Hannover)

Place: MPL / Large seminar room (*435)

Abstract:

This talk will provide a broad overview on cell manipulation using focused pulsed lasers and laser interaction with gold nanoparticles. Several chemical or physical techniques have been previously developed to deliver extracellular biologically relevant molecules to living cells. However, cell specific targeting or high-throughput delivery while maintaining cell viability has remained a challenge.  Laser poration of mammalian cells has recently emerged as an effective means to create transient and sub-micron-sized disruptions on the cell membrane. This light-tissue interaction mechanism depends on the pulse duration and wavelength of light. To address cell-specific targeting, a tightly focused femtosecond laser has been used to transfect single cells such as primary neurons and embryonic stem cells. In order to treat thousands of cells, the interaction of gold nanoparticles with pulsed lasers was utilized for high-throughput cell poration but with localized targeting. As an example, endosomal membranes can be precisely disrupted enabling the intracellular release of molecules within the cytoplasm. Overall these studies demonstrate the effectiveness of pulsed lasers and its interaction with gold nanoparticles for targeted cell disruption and transfection.

Thursday 26. November 2015

IMPRS monthly meeting

 

Organisation: Katharina König (MPL/ Sandoghdar Division)

Talk: High-k Materials and embedded Nanocrystals for Electronic and Photonic Applications

Speaker: Prof Dr Johannes Heitmann (Institute for Applied Physics, Technical University Freiberg)

Place: MPL / Seminar room of Sandoghdar Division (*478)

Abstract:

High-k materials play a major role in semiconductor research and development. Semiconductor industry made a step towards high-k dielectrics like Al2O3, HfO2 and ZrO2 for MIM capacitors in DRAM and rf applications [1], as well as for gate dielectrics for sub 45 nm devices or in high electron mobility transistor in GaN based hetero structures. Implementing high-K materials into the process flow of a GaN based high electron mobility transistor needs to adapt the whole process sequence, like thermal budget of electrode formation etc. [2]. Furthermore, in solar industry the high-k material Al2O3 is discussed to replace SiN passivation layer for the newest PERC concept [3,4].

Beyond the already established applications routes high-k materials show superior properties as matrix material for semiconductor quantum dots – rare earth element alloys to enhance their optical and electrical properties. Embedded group IV nanocrystals like Si and Ge show superior charge storage properties in high-K matrix materials deposited via rf-magnetron sputtering. Ge nanocrystals embedded in an amorphous TaZrOx matrix as blocking oxide implemented in a metal-insulatorsemiconductor capacitor show a voltage hysteresis in a capacitance-voltage slope of 5 V and a programming voltage – hysteresis voltage slope of nearly 1 [5]. In case of embedded Au nanoparticles in sol gel deposited Er doped ZrO2 films a temperature stability of the Au nanoparticle related surface plasmon resonance up to 1000°C annealing temperature could be shown [6].

In this contribution we will review our efforts to realize optimized properties of the high-K materials for the needs of the different applications as matrix material for nanocrystalline semiconductors for optical and electrical applications and as passivation layer for Si photovoltaics or nitride electronics.

[1] J. Heitmann, A. Avellan, T. Boescke, E. Erben, B. Hintze, S. Jakschik, S. Kudelka, and U. Schroeder, HfAlO
and HfSiO Based Dielectrics for Future DRAM Application, ECS. Trans. 2 (2006) 217.
[2] Schmid, A.; Schröter, Ch.; Otto, R.; Schuster, M.; Klemm, V.; Rafaja, D.; Heitmann, J., Appl. Phys. Lett.
106, 053509 (2015)
[3] Benick et al. Applied Physics Letters 2008; 92; 253504
[4] F. Kersten, A. Schmid, S. Bordihn, J. W. Müller, J. Heitmann, Energy Procedia, 38, p. 843, (2013)
[5] D. Lehninger, P. Seidel, M. Geyer, F. Schneider, V. Klemm, D. Rafaja, J. von Borany, J. Heitmann, Appl.
Phys. Lett. 106, 023116 (2015)
[6] S. Seidel, A. Sabelfeld, R. Strohmeyer, G. Schreiber, V. Klemm, D. Rafaja, Y. Joseph, and J. Heitmann, J. of
Appl. Phys., submitted for publication.

Thursday 12. November 2015

IMPRS get-together

 

Organisation: Eugene Kim (MPL/ Vollmer Lab)

Talk: Enhancing Nonlinear Optical Signal in χ(2) Nanomaterials

Speaker: Prof Dr Rachel Grange (ETH Zurich, Department of Physics, Optical Nanomaterial Group)

Place: MPL / Large seminar room (*435)

Abstract:

Nonlinear optical processes are known to be weak in bulk materials and extremely small at the nanoscale since they mainly scale with the volume. Here I will show how we enhance second-harmonic generation in two typical c2 non centrosymmetric nanomaterials. First, in barium titanate nanoparticles, we take advantage of Mie scattering resonances. Second, in lithium niobate nanowires, we demonstrate phase-matching and use it to increase the guided second-harmonic power by a factor of more than 80. We also increase non-phase-matched guided second-harmonic by engineering the nanowire length. Those bright nanostructures can serve for developing compact efficient nonlinear optical sources or waveguides.

Monday 05. October 2015

IMPRS annual meeting

 

Place: Tagungshotel Behringers, Gößweinstein

Invited talks: Jean-Michel Gerard, Anne Sentenac, Mikael Käll, Albert Stolow

Block lectures: Peter Hommelhoff, Christoph Marquardt

Other: panel discussion, poster session, student talks

For more information: flyer, schedule, programme with abstracts

Wednesday 09. September 2015

IMPRS get-together

 

Organisation: Daqing Wang (MPL/ Sandoghdar Division)

Talk: Wide Field STED Microscopy and Optical Nanoscopy with Excited State Saturation at Liquid Helium Temperatures

Speaker: Dr Jean-Baptiste Trebbia (Institut d'Optique Graduate School, CNRS &  Université de Bordeaux)

Place: MPL / Large seminar room (*435)

Abstract:

Recent developments in super-resolved microscopy (PALM, STORM, RESOLFT, STED ...) have been able to achieve an optical resolution down to few nanometers. Among these techniques, the Stimulated Emission Depletion has the advantage to be a super-resolution technique (not a superlocalization technique) and therefore could be use to image dense labeled fluorescent samples. However, being a scanning point method, this technique needs to be parallelized for fast wide-field imaging. Here, I will present how we achieved a large STED parallelization microscopy using well designed optical lattice for depletion, together with a fast camera for detection. We obtained, with 100 intensity "zeros" generated by a four-beam interference, a field of view of 3*3 μm2 at an acquisition rate of 12.5 frames per second and with a super-resolution of 70 nm [1,2]. In the second part of my talk, I will focus on a simple super-resolution optical microscopy method operating at cryogenic temperatures, which is based on the optical saturation of single fluorescent molecules with a doughnut-shaped beam. Sub-5 nm resolution is achieved with extremely low excitation intensities [3]; a million times lower than those used in room temperature STED microscopy. Compared to super-localization approaches, our technique offers a unique opportunity to super-resolve single molecules having overlapping optical resonance frequencies, paving the way to the study of coherent interactions between single emitters and to the manipulation of their degree of entanglement.

 

References :

[1] Yang B., FANG C.-Y., Chang H.-C., Treussart F., Trebbia J.-B. and Lounis B., Polarization Effects in Lattice-STED Microscopy, Faraday Discussion (2015).

[2] Yang B., Przybilla F., Mestre M., Trebbia J.-B., Lounis B., Large parallelization of STED nanoscopy using optical lattices, Optics Express (2014).

[3] Yang B., Trebbia J.-B., Baby R., Tamarat Ph. and Lounis B., Optical Nanoscopy with Excited State Saturation at Liquid Helium Temperatures, Nature Photonics (2015).