Optics Seminar
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2014-11-27 (Thursday)
room 1.40, Pasteura 5 at 09:15 
prof. Krassimir Panajotov (Vrije Univeristeit Brussel and Institute of Solid State Physics, Sofia.)Nonlinear dynamics of semiconductor lasers and its applications
2014-11-20 (Thursday)
room 1.40, Pasteura 5 at 09:15
Mr. Martin Jansen (Heinrich Heine Universitaet Duesseldorf, Niemcy)Electron-positron pair creation in bichromatic laser fields
The ongoing progress in laser technology leads to field strengths at which the vacuum becomes unstable and breaks down into electron-positron pairs, offering prospects to eventually see the Schwinger effect in the laboratory. As predicted by Breit and Wheeler in 1934, already the collision of two single energetic photons can produce a pair, yet with an extremely small probability. In contrast, photon densities achieved in focus areas of modern lasers facilitate multiphoton reaction channels, decreasing the required photon energy and leading to measurable particle yields.We present detailed calculations within the framework of laser-dressed strong-field QED. We investigate a setup in which two co-propagating laser beams collide with highly energetic gamma quanta, which allows two different interaction regimes to be examined. For low-intensity lasers with a suitably-chosen frequency ratio, interference effects between production channels of different photon-number combinations can be observed in the angular distributions of the particles and even in the total particle count rate. For a high-intensity optical laser used in an experiment to observe the Schwinger effect, we demonstrate how the addition of aow-intensity yet high-frequency laser can strongly enhance the particle yield.
2014-11-13 (Thursday)
room 1.40, Pasteura 5 at 09:15
dr Piotr Fita (IFD UW)Optical studies of interfacial chemistry
2014-11-06 (Thursday)
room 1.40, Pasteura 5 at 09:15
mgr Michał Nejbauer (IFD UW)Uniwersalny układ do ultraszybkiej spektroskopii ramanowskiej
2014-10-30 (Thursday)
room 1.40, Pasteura 5 at 09:15
Michał Parniak (IFD UW)Efekty wielofotonowe w ciepłych parach atomowych - propozycja nowego kwantowego interfejsu światło-atomy
Multi-photon effects in warm atomic vapours - proposal for a new quantum light-atom interface
2014-10-23 (Thursday)
room 1.40, Pasteura 5 at 09:15
dr Ziaul Hoque (IFD UW)Ultrafast molecular alignment and nanoplasmonics enhanced phenomena
2014-10-16 (Thursday)
room 1.40, Pasteura 5 at 09:15
prof. Giacomo Roati (University of Florence, Italy)Degenerate 6Li atoms in Florence: current and future experiments
I will present the new experimental machine at LENS to study strongly-correlated fermionic 6Li atoms. We have recently demonstrated a gray molasses scheme operating on the D1 atomic transition to produce degenerate quantum gases of 6Li with a large number of atoms.Thanks to this novel sub-Doppler cooling phase we lower the initial temperature of 109 atoms from 500 to 40 μK. By evaporating two-state spin mixtures into an optical trap, we produce molecular Bose-Einstein condensates of up to 5×105 molecules and weakly-interacting degenerate Fermi gases of 7×105 atoms at T=TF < 0.1. We are currently superimposing on the quantum gases a thin optical barrier whose size σ≃1.5 μm is comparable with the mean inter-particle distance. I will discuss on the different regimes that we plan to study in thisconfiguration, going from the itinerant ferromagnetic phases to the observation of Josephson-like tunneling of fermionic pairs.
2014-10-09 (Thursday)
room 1.40, Pasteura 5 at 09:15
dr Gotz Lehmann (Heinrich-Heine University Dusseldorf)High-order harmonics from laser-irradiated plasmas
The interaction between femtosecond laser pulses and plasma surfaces can lead to the generation of high-order harmonics. This mechanism provides an alternative to harmonic generation in gas targets and is especially interesting in the view of conversion efficiency.Since the laser pulse amplitude for laser-plasma interaction (typically above 1018 W/cm2) can vastly exceed the intensities used for atomic harmonics (up to 1014 W/cm2) the generated radiation can be far more intense. In the relativistic regime the harmonics intensity can even exceed the intensity of the focused laser pulse.Harmonic radiation generated from relativistic laser-plasma interaction can be used for nonlinear optics in the extreme ultraviolet regime (XUV) and the generation of atto-second radiation. On the other hand the details of the laser-plasma interaction influence the harmonics spectrum, i.e. details of the harmonic spectrum reveal information about the motion of the plasma surface, plasma waves, electron transport inside the plasma and large electric and magnetic fields at the surface.In the presentation the physics behind high-order harmonic generation in the relativistic regime of laser-plasma interaction will be presented. Prospective applications as coherent XUV sources are highlighted. The influence of plasma parameters such as surface density gradient scale-length and plasma temperature on the harmonics spectrum will be discussed.
2014-10-02 (Thursday)
room 1.40, Pasteura 5 at 09:15
prof. Kazimierz Rzążewski (Centrum Fizyki Teoretycznej PAN)Każdy głos się liczy
Seminarium odbędzie się w nowej siedzibie, w budynku przy ul. Pasteura 5.Sala 1.40 znajduje się na I piętrze (windą obok stanowiska recepcji na parterze). Po opuszczeniu windy należy się skierować w prawo. Sala 1.40 znajduje się w części oddzielonej od głównego korytarza szklanymi drzwiami.