Microwavephysics and Atmospheric Physics
Biomedizinische Photonik
Ultrafast Science and Technology
HS 2017  ·  FS 2017
HS 2016  ·  FS 2016
HS 2015  ·  FS 2015
HS 2014  ·  FS 2014
HS 2013  ·  FS 2013
HS 2012  ·  FS 2012
HS 2011  ·  FS 2011
Last update: 18.10.2017
HS 2017: Seminare über Ultrafast Science and Technology
Thursday 11:15am
Vorträge, die innerhalb der nächsten Tage stattfinden, sind speziell markiert.
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Freitag, 04.08.2017

Ultrafast and ultrasensitive coupling to molecular vibrations

Zeit: 10:15 Uhr
Hörsaal: B116
 
Dr. Johannes Haase
Paul Scherrer Institute PSI
Villigen Switzerland

The unification of ultrafast laser physics and chemistry opens new insights to the fundamentals of chemical reactions. The ultimate femto-chemistry probe is the X-ray free electron laser providing ultrashort pulses in the significant wavelength region for inter-atom investigations. Time resolved studies of ensemble reactions however rely on a synchronization and ultrafast initialization. Chemical processes that are triggered by heat are especially tricky since heat is defined as an equilibrium state that is not reached on ultrafast time scales. In my talk, I will present ultrafast heating mechanisms and coupling to molecular vibrations. These studies also require ultrasensitive detection of molecular monolayers that is reached by plasmonic field enhancement of nanoscopic antennas.

 
Donnerstag, 21.09.2017

Advancing Ultrashort Laser Pulse Technology: Controlling Ultrafast Electron Motion

Zeit: 11:15 Uhr
Hörsaal: B116
 
Dr. Yunpei Deng
Paul Scherrer Institute PSI
Villigen Switzerland

State-of-the-art laser technology is on the verge of providing synthesized waveforms at optical frequencies. Such flexibility in shaping arbitrary light waveforms permits sculpting an electric force for steering electrons in any desired fashion within atomic, molecular and solid systems, on the electronic time scale. This has promising potential in pushing the frontiers of attosecond physics and of coherent control schemes to completely unexplored regions.

Optical parametric chirped-pulse amplifier (OPCPA) systems can produce nearly single-cycle pulses at a mJ energy level, or few-cycle pulses at a hundred mJ level. In my talk I will present the details of a mid-IR OPCPA laser system that I developed at MPQ. As I will show, this system has already demonstrated an output of 1.2-mJ, 1.5-cycle (10.3fs) pulses at 2.1µm central wavelength and at 3 kHz repetition rate. Such source is the key to achieving HHG X-ray photons in the keV domain, and is also important to a wide range of highly interesting applications, such as the investigation of ultrafast structural dynamics and conformational changes of relevant molecules in biology. An additional benefit of the IR carrier wavelength is the increased duration of its optical cycle (e.g. 7 fs for 2.1 µm) compared with a NIR pulse (e.g. 2.5 fs for 750 nm). The increased spacing between successive half-cycles of the laser pulse provides a sufficient time window to capture the full dynamics of an arbitrary sub-femtosecond relaxation process, before the identical process is re-triggered by the next half-cycle of the laser pulse. It is a powerful and unique source for coherent control, ionization and dissociation experiments. I will also show how an OPCPA system, which can be developed to deliver more than two-octave bandwidth pulses, is capable of producing sinusoidal-like, square, sawtooth or any arbitrary waveforms. Such laser pulses will open the door to many ultrafast coherent control applications.

 
Donnerstag, 28.09.2017

No seminar due to EAAC

Zeit: 11:15 Uhr
Hörsaal: B116
 

 
Donnerstag, 05.10.2017

THz-driven graphene plasmon-based undulator

Zeit: 11:15 Uhr
Hörsaal: B116
 
David Rohrbach
Institute of Mathematics
University of Bern

By using a classical undulator with an alternating magnetic field one can produce X-ray with a high energetic electron beam. Numerical simulations of the new type of graphene plasmon-based undulator, which is driven by a THz source, indicate narrow-band emissions in the X-ray even for a low energetic beam and a total undulator length of some centimeters.

 
Donnerstag, 12.10.2017

No seminar due to UFO

Zeit: 11:15 Uhr
Hörsaal: B116
 

 
Donnerstag, 19.10.2017

Nonlinear THz spectroscopy and NIR pump THz ellipsometry

Zeit: 11:15 Uhr
Hörsaal: B116
 
Gregory Gäumann
Institute of Applied Physics
University of Bern

In the first part of this talk measurements on graphene and vanadium dioxide in our high field THz setup will be presented and compared with simulations. For graphene an increase in transmission (saturable absorption) as high as 12% for strong fields is observed and it’s dependence on the Fermi level was measured for the first time. The obtained results are compared to a simulation that is based on a simple thermodynamic energy balance. For VO2 the onset of a THz field induced metal to insulator transition is observed. In the second part recent progress in building up a NIR pump THz ellipsometer is reported and first measurements on silicon and VO2 are presented.

 
Donnerstag, 26.10.2017

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Zeit: 11:15 Uhr
Hörsaal: B116
 
Leonardo Gasparini
Fondazione Bruno Kessler, Trento (IT)

 
Donnerstag, 02.11.2017

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Zeit: 11:15 Uhr
Hörsaal: B116
 
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Donnerstag, 09.11.2017

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Zeit: 11:15 Uhr
Hörsaal: B116
 
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Donnerstag, 16.11.2017

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Zeit: 11:15 Uhr
Hörsaal: B116
 
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Donnerstag, 23.11.2017

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Zeit: 11:15 Uhr
Hörsaal: B116
 
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Donnerstag, 30.11.2017

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Zeit: 11:15 Uhr
Hörsaal: B116
 
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Donnerstag, 07.12.2017

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Zeit: 11:15 Uhr
Hörsaal: B116
 
Dr. Bänz Bessire
Institute of Applied Physics
University of Bern

 
Donnerstag, 14.12.2017

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Zeit: 11:15 Uhr
Hörsaal: B116
 
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Donnerstag, 21.12.2017

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Zeit: 11:15 Uhr
Hörsaal: B116
 
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