Rainbow pattern from laser-plasmas
Intense light pulses that can precisely sculpt solid materials also generate dazzling rainbow patterns that reveal information about the surface.
Not just a pretty face. This colorful pattern of light scattered from a solid surface being hit with laser pulses can convey details of the surface damage, such as the size of the laser-generated crater.
A spectacular sunburst of colored light produced as a laser beam bores into a solid surface could reveal information about the damage the light causes, according to a report in Physical Review Letters. The authors observed the rainbow pattern as they blasted a series of transparent materials such as glass and quartz with intense laser pulses. The team says that this effect, surprisingly overlooked until now, could offer a way of monitoring laser ablation, a technique used in fields as varied as dental surgery and art preservation.
- Ciliary White Light: Optical Aspect of Ultrashort Laser Ablation on Transparent Dielectrics
Yi Liu, Yohann Brelet, Zhanbing He, Linwei Yu, Sergey Mitryukovskiy, Aurélien Houard, Benjamin Forestier, Arnaud Couairon, and André Mysyrowicz
Phys. Rev. Lett. 110, 097601 (2013)
Improved stability of laser-plasma electron beam
Laser-plasma accelerators can produce high quality electron beams, up to giga-electronvolts in energy, from a centimeter scale device. The properties of the electron beams and the accelerator stability are largely determined by the injection stage of electrons into the ac- celerator. The simplest mechanism of injection is self-injection, in which the wakefield is strong enough to trap cold plasma electrons into the laser wake. The main drawback of this method is its lack of shot-to-shot stability. Researchers from LOA have demonstrated the existence of two different self-injection mechanisms. Transverse self-injection is shown to lead to low stability and poor quality electron beams, because of a strong dependence on the intensity profile of the laser pulse. In contrast, longitudinal in- jection, which is unambiguously observed for the first time, is shown to lead to much more stable acceleration and higher quality electron beams. These results are published in Nature Communications, February 19th, 2013.
Nature Photonics, December 2012 - The dynamics of electrons in atoms and molecules is extremely fast (order of magnitude: attosecond, or 10-18 s). One way to study these phenomena is to use pulses of ultra-short light on these timescales. With the demonstration carried out at the Laboratory of Applied Optics (LOA, CNRS / ENSTA-ParisTech / Polytechnique) by researchers from LOA and CEA-IRAMIS, it is possible to have today unique light sources. From a single laser pulse focused onto a plasma, several isolated attosecond pulses can be produced. The beams are well angularly separated and perfectly synchronized. The attosecond "lighthouse" is an ideal light source for future pump-probe experiments to study the ultrafast dynamics of electron in matter.
These results were published in Nature Photonics, 1 December 2012.
New LaserLab coordinator
Claes-Göran Wahlström from the Lund Laser Centre at Lund University, Sweden, has been elected as the new Coordinator of LASERLAB-EUROPE, the European Laser consortium. He succeeds Wolfgang Sandner, Max-Born-Institute, Berlin, who lead the consortium and its evolution through several successive Framework Programmes of the EU, starting with the FP5 thematic network LASERNET in 2001. Meanwhile the consortium has grown to 28 partner institutions, comprising, together with subcontractors, 19 European countries. It has just started a new project period, funded by the European Union and ranging from 2012 through 2015.
Claes-Göran Wahlström is Professor of Physics at the Lund University, where he is the head of the Atomic Physics Division, at the Department of Physics, and of the Lund Laser Centre. His own research addresses ultra-high intensity laser matter interactions, and laser-driven particle acceleration in particular. Since 2010 he is an elected member of the Royal Swedish Academy of Sciences.
The hand-over took place during the General Assembly Meeting in Munich on October 25. In his inauguration speech, Claes-Göran Wahlström thanked Wolfgang Sandner for his achievements, having brought together two laser communities, the former “high-energy laser infrastructures” and the “analytical laser facilities”, and having led them to become a powerful network. He also pointed out the options for the further development of the consortium and his commitment to lead LASERLAB-EUROPE into a successful and sustainable future.
The LASERLAB-EUROPE partners congratulate Claes-Göran Wahlström to his election and wish him all the best for the future coordination of the LASERLAB network. They also thanked Wolfgang Sandner who will assume new tasks in the European ESFRI project ELI, the “Extreme Light Infrastructure”, the world’s first international scientific laser project. Claes- Göran Wahlström will be assisted in his new tasks by the Forschungsverbund Berlin e.V., the legal entity holding the LASERLAB grant agreement with the EC, and by the LASERLAB Berlin office, who both will continue in their functions.
LOA belongs to the consortium since its start more than 10 years ago. It plays an active role in the research and access facility programs as well as in the coordination of the consortium with its recent election at the Management Board.
ENSTA-ParisTech moves to Palaiseau
The french National School of Advanced Techniques (ENSTA ParisTech) has just moved this september from Paris to Palaiseau. ENSTA ParisTech was located in Paris since its creation in 1970. In 2012, the school of engineering is moving on the Paris-Saclay Campus, located on the Saclay plateau. The new campus provides teaching facilities, student accommodations, catering and hotel services and a range of outstanding sporting facilities for the people who live, work and study there. Saturday, October 6, 2012, a first event has gathered around 1000 people came to visit the new school in a friendly and musical atmosphere. The official inauguration took place Saturday, October 13, 2012.
ERC "starting Grant award at LOA
Jerôme FAURE, a CNRS staff researcher at LOA, has been awarded a junior European ERC starting grant (June 2012). This highly selective program favors the emergence of the next-generation of research leaders, who bring new ideas, and it encourages highly talented researchers at an early stage of their career to seek advancement. ERC Starting Grants aim to support up-and-coming research leaders who are about to establish or consolidate a proper research team and to start conducting independent research.
Jérôme FAURE will develop innovative femtosecond laser-plasma based electron source at high repetition rates to study the ultrafast structures of the matter. His research program will be done with the latest LOA laser infrastructures.
LOA results highlighted
Two scientific results of the Laboratoire d'Optique Appliqée (LOA) are highlighted in the May 2012 covers of Nature Physics and Nature Photonics. These two results on the attosecond control of plasma and on the generation of all-optical gamma-ray beam by Compton scattering, were obtained by three teams of the laboratory, FLEX (X-ray source development and application), SPL (Particle source development and application) and PCO (Physics of optical cycle) and using two LOA experimental facilities, the "Salle Jaune" infrastructure (30 TW femtosecond laser) and the "Salle Noire" infrastructure (ultrafast laser of a few optical cycles and controlled in phase). More details can be found following the links:
-Attosecond Control of plasmas-
-All Optical gamma-ray beam-
Attosecond control of plasmas demonstrated
- Generating for the first time an ultrashort radiation in a controlled manner by the use of a plasma, Nature Physics -
To observe ultrafast phenomena such as the movement of electrons in the matter, researchers need sources capable of producing extremely short light pulse radiation and energy. Even if devices capable of emitting pulses in the attosecond (10-18 seconds) already exist, many teams are trying to push the limits of their intensity and duration. The team led by the Laboratory of Applied Optics (LOA, CNRS / ENSTA-ParisTech / Ecole Polytechnique), in collaboration with CEA-Saclay and the Laboratory for the Use of Intense Lasers (LULI, CNRS / CEA / Ecole Polytechnique / UPMC), succeeded for the first time, to accelerate and guide electrons in a controled manner in a plasma using a laser. These electrons excite the plasma, which then emits electromagnetic pulses to ultra short wavelengths in the range of extreme ultraviolet. The attosecond radiation energy can be used to probe the ultrafast electronic processes. This work is published in Nature Physics (online - March 26, 2012).
Launch of 2 new ANR projects at LOA
Two new research programs selected by the French Ministery of Research (ANR), ILA and ROLEX, have been lauched at LOA this february, 2012.
The ILA project aims at pushing forward the development of compact laser-driven sources of particles and radiation by using the next generation of multi-PW lasers, and measuring laser-accelerated high energy (GeV) particles with innovative diagnostic approaches. It combines the expertise of the French LOA group in the particle acceleration field to the Romanian IFIN-HH expertise in high-energy accelerator beam and particle detection technology. It’s an ambitious proposal as it addresses the development of four key particle and radiation sources: electrons, ions, energetic radiation and neutrons.
The main objective of ROLEX is to numerically and experimentally investigate an innovative approach to produce the very first multi-microjoules monochromatic coherent femtosecond laser source in the 10-nm range enabling to overpass the current bottlenecks. Our approach is based on the guiding of frequency-doubled multi-TW laser driver focused into a high density plasma soft X-ray amplifier driven by ultrafast recombination pumping.
ROLEX brings together a unique combination of French laboratories from the "Plateau de Saclay" working on ultra-intense lasers, laser based X-ray sources, guiding of high intensity infrared laser pulses, and hydrodynamic and atomic physics (LOA, CEA, ISMO, LULI, LPGP).
"Equipements d'Excellence" ATTOLAB selected
The selection of the second round of national "Equipement of Excellence (EQUIPEX)" has just been released. Two projects in which the LOA is a partner, ATTOLAB and MORPHOSCOPE2, were selected. EQUIPEX are part of the operation "Investments for the Future" set up by the French Ministry of Research. They aim to provide France with scientific equipment of intermediate size (ie, between 1 and 20 million euros), which will benefit all areas of research. ATTOLAB's goal includes the establishment of a new experimental center, based on the Paris-Saclay campus, dedicated to studies of ultrafast electron dynamics in areas such as atomic, molecular, chemical, solid state physics and plasma physics. It was awarded 5 million euros. The CEA is the coordinator (SPAM) and the project gathers 9 partners. The LOA duty is to specifically set up systems for plasma physics. MORPHOSCOPE2 is an infrastructure project incorporating technological developments in microscopic imaging, storage and algorithmic analysis of datato advance the understanding of biological processes and in predicting their behavior according to genetic or environmental variations. It is coordinated by the Ecole Polytechnique (LOB) and gathers around twenty partners.
Press release of the selected 36 national projects: here, with the two summaries ATTOLAB and MORPHOSCOPE2.