DM: Tsuneto: Development of CEP-stabilized high power CPA/OPA lasers and direct generation of highly phase-matched isolated attosecond pulses

One of the most crucial issues for the present attophysics is to increase the pulse energy of isolated attosecond pulses (IAP.s). For this purpose, there are two crucial experimental challenges to demonstrate; one is to develop multi-mJ few cycle lasers with a stabilized carrier-envelope phase (CEP) and the other is to achieve the phase-matching highly between the few cycle pulses and high harmonics of them. In this talk, I will present our research activities on both challenges. First, I will present our recent results of RIKEN based on our TW-class 2-cycle laser system (5 fs, 780 nm, 5 mJ, 1 kHz). Recently, we have stabilized CEP of this system with two feedback loops and by blocking mechanical vibrations on the laser system thoroughly. Through the phase matching process, we could select the supercontinuum component of the harmonics without any use of bandpass filters such as Mo/Si mirrors. By using a heterodyne interferometry using mixed gases, we verified that we could select IAP directly. Second, I will briefly introduce our recent results at Imperial College London on constructing a CEP-stabilized high power OPA (optical parametric amplification) laser. CEP-stabilized seed pulses were generated using type II DFG of different frequency components of the supercontinuum generated with a hollow fiber compression technique, and the seed pulses were amplified by two-stage OPA.s. Final output pulses had a pulse energy of 500 μJ, pulse duration of 40fs, and tunable wavelength from 1300-1800 nm. As the first demonstration of this handmade laser, we could generate high harmonics up to 47th using a tube target filled with Xe gas.
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JC: Stefan: Study of high Mach number laser driven blast waves in gases

A series of experiments were performed examining the evolution of blast waves produced by laser irradiation of a target immersed in gas. Blast waves were produced by illumination of wires by 1 kJ, 1 ns laser pulses from the Z-Beamlet laser at Sandia National Laboratories. The blast waves were imaged by probe laser pulses at various times to examine the trajectory, radiative precursor, and induced perturbations on the blast wave front. Well de.ned perturbations were induced on the blast wave front with arrays of wires placed in the gas and the results of the experiments are compared to the theoretical predictions for the Vishniac overstability. It is found that the experimental results are in general agreement with these theoretical predictions on thin blast wave shells and are in quantitative agreement in the simplest case.
http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PHPAEN000017000011112104000001&idtype=cvips&prog=normal
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DM: Damien: OPA/OPCPA in crystals and fibres

I will do a general discussion/presentation about OPA/OPCPA in non linear crystal and in fiber. I will show some experimental results related to what I did in the PETAL Petawatt project.
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DM: Jon: Programme Grant overview & introduction

we plan to extend attosecond science to larger molecules and condensed phase systems building upon our present activity in HHG spectroscopy and attosecond pulse generation. I hope to give a short briefing on the scientific plans
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JC: Misha: Radiation Generated by the Ultrafast Migration of a Positive Charge Following the Ionization of a Molecular System

Electronic many-body effects alone can be the driving force for an ultrafast migration of a positive charge created upon ionization of molecular systems. Here we show that this purely electronic phenomenon generates a characteristic IR radiation. The situation when the initial ionic wave packet is produced by a sudden removal of an electron is also studied. It is shown that in this case a much stronger UV emission is generated. This emission appears as an ultrafast response of the remaining electrons to the perturbation caused by the sudden ionization and as such is a universal phenomenon to be expected in every multielectron system.
http://prl.aps.org/abstract/PRL/v106/i5/e053001
What I want everyone to think about is:
- What is the role of the detached electron that they have completely neglected?
- Can this radiation be observed, and if yes, will it be coherent?
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DM: Luis: how to grow micro and nanostructures, with both, nanosecond and femtosecond laser pulses

(i) Laser irradiation of materials with laser pulses whose energy density is around the ablation limit, no matter whether they are femtosecond or nanosecond pulses, do produce microconical structures despite of the, most likely, different mechanisms involved. These structucture do have several interesting applications.
(ii) We will show how a metalic thin film of nanoparticles can be rearranged just by shining few laser pulses with a well defined intensity structure.
PPT slides to follow...

DM: Malte: Molecular structure dependence of recollision induced fragmentation in N2

After converting the VMI in the Red Dragon lab to an ion time-of-flight spectrometer, it is currently used to investigate those inelastic electron recollisions, which lead to fragmentation. Inelastic recollisions lead to electron-electron interactions in the outer shell of the molecule and investigating them is one of the objectives of attosecond science.
In the lab, we are trying to find out if the recollision induced fragmentation of N2 depends on the alignment of the molecule, or in other words if fragmentation is more probable if the electron hits the molecule parallel or perpendicular with respect to the bond.
I will give a detailed description of the required experimental steps to find an answer to that question and present a few intermediate results. I will try to raise a few questions about the setup and future plans to get input from the group.
Most of the experimental issues are mentioned in the following paper, written by a very familiar Irish man: http://pra.aps.org/abstract/PRA/v73/i4/e043401 Nevertheless, I will briefly discuss them during the meeting as well.
PPT slides to follow...