33 research outputs found
Extremely high-intensity laser interactions with fundamental quantum systems
The field of laser-matter interaction traditionally deals with the response
of atoms, molecules and plasmas to an external light wave. However, the recent
sustained technological progress is opening up the possibility of employing
intense laser radiation to trigger or substantially influence physical
processes beyond atomic-physics energy scales. Available optical laser
intensities exceeding 10^{22}\;\text{W/cm^2} can push the fundamental
light-electron interaction to the extreme limit where radiation-reaction
effects dominate the electron dynamics, can shed light on the structure of the
quantum vacuum, and can trigger the creation of particles like electrons, muons
and pions and their corresponding antiparticles. Also, novel sources of intense
coherent high-energy photons and laser-based particle colliders can pave the
way to nuclear quantum optics and may even allow for potential discovery of new
particles beyond the Standard Model. These are the main topics of the present
article, which is devoted to a review of recent investigations on high-energy
processes within the realm of relativistic quantum dynamics, quantum
electrodynamics, nuclear and particle physics, occurring in extremely intense
laser fields.Comment: 58 pages, 26 figures, version accepted by Reviews of Modern Physic
Power amplification for petawatt Ti: Sapphire lasers: New strategies for high fluence pumping
One of the major bottlenecks when we pump large
Ti:Sapphire crystals, to reach Petawatt–level laser amplification, is the
careful control of the spatial energy distribution of Nd:Glass pump lasers.
Commercially available nanosecond Nd:Glass and Nd:YAG lasers exhibit poor
spatial profile quality especially in the near and in the intermediate
field, which can lead to local hot spots, responsible of damages in
crystals, and parasitic transverse lasing enhancement, strongly dependent on
the profile of the pump beam . For these reasons, it is mandatory to keep
the pump beam intensity profile as flat as possible on the pumped crystal.
To guarantee the best pumping conditions we are investigating the combined
use of DOE (diffractive optical elements) and optical smoothing techniques.
In parallel we are starting a study on laser induced damages mechanisms in
crystal. With DOE and microlens arrays we plan to guarantee to the beam a
supergaussian shape. Simulation and first experiments with both optical
systems show that a flat top spatial profile with less than 10%
fluctuations and a 8th order supergaussian is possible with the present
technology.Optical smoothing will keep the beam free of hot spots. We
especially focused on the smoothing techniques involving optical fibers.
This is the first time to our knowledge that this technique is applied to
the pumping beams for Ti:Sapphire systems. A deep study of laser-crystal
interaction will allow us to fully understand the damages created by hot
spots. The knowledge of the phenomena involved in laser damages on
Ti:Sapphire is mandatory to control the pumping processes and thresholds. In
conclusion, mixing the advantages of these different approaches to overcome
this bottleneck will allow us to amplify in a safety way femtosecond laser
beams to the Petawatt level using Ti:Sapphire crystals
Optical component requirement for ultra-short and ultra-intense lasers (orale)
International audienc
Complete characterization of damage threshold in titanium doped sapphire crystals with nanosecond, picosecond and femtosecond laser pulses
International audienc
Chaînes laser intenses à contraste élevé par amplification directe dans un milieu gazeux à excimères*
Search for stimulated photon-photon scattering in vacuum
We have searched for stimulated photon scattering in vacuum at a
center of mass photon energy of 0.8 eV.
The QED contribution to this process is equivalent to four wave
mixing in vacuum.
No evidence for scattering was observed.
The corresponding upper limit of the cross-section is