Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A feeling for the (light) wave

13.01.2014
A team at the Laboratory for Attosecond Physics has designed and built a simplified detector for the measurement of the waveforms of pulsed laser radiation.

A team in the Laboratory for Attosecond Physics (LAP) at the Max-Planck-Institute of Quantum Optics has taken another step toward the achievement of complete control over the waveform of pulsed laser light.


A mode-locked laser at the Max-Planck-Institute of Quantum Optics emits flashes of light that last for a few femtoseconds. A new glass-based phase detector now enables simpler and more precise control of their waveforms. (Graphic: Thorsten Naeser)

Together with colleagues based at LMU and the Technische Universität München (TUM), they have constructed a detector which provides a detailed picture of the waveforms of laser pulses that last for a few femtoseconds.

Unlike conventional gas-phase detectors, this one is made of glass, and measures the flow of electric current between two electrodes that is generated when the electromagnetic field associated with the laser pulse impinges on the glass.

The researchers can then deduce the precise waveform of the pulse from the properties of the induced current. Knowledge of the exact waveform of the femtosecond pulse in turn makes it possible to reproducibly generate light flashes that are a thousand times shorter – lasting only for attoseconds – and can be used to study ultrafast processes at the molecular and atomic levels (Nature Photonics, DOI:10.1038/nphoton.2013.348, 12 January 2014).

Modern mode-locked lasers are capable of producing extremely brief light flashes that last for only a few femtoseconds (1 fs is one-millionth of a billionth of a second). With durations of as little as 2.5 fs, such pulses correspond very few oscillations of the electromagnetic field, indeed to only 1 to 2 complete cycles, which are however preceded and followed by waves of lower amplitude that are rapidly attenuated. In laser physics it is often important to know more about the precise form of the high-amplitude oscillations, because this tells one the shape of the electromagnetic fields and allows them to be utilized in an optimal manner to probe ultrashort processes that occur at the level of molecules and atoms.

A team led by Prof. Ferenc Krausz and including his doctoral student Tim Paasch-Colberg has now developed a glass-based detector that allows one to accurately determine the form of the light waves that make up an individual femtosecond pulse. In the course of experiments performed over the past several years, physicists in the group have learned that when pulsed high-intensity laser light impinges on glass, it induces measurable amounts of electric current in the material (Nature, 3 January 2013). Krausz and his colleagues have now found that the direction of flow of the current generated by an incident femtosecond pulse is sensitively dependent on the exact form of its wave packet.

In order to calibrate the new glass detector, the researchers coupled their system with a conventional instrument used to measure waveforms of light. Since the energy associated with the laser pulse is sufficient to liberate bound electrons from atoms of a noble gas such as xenon, the “classical” detector measures the currents caused by the motions of these free electrons. But there is a catch – the measurements must be done in a high vacuum. By comparing the currents induced in the new solid-state detector with the data obtained using the conventional apparatus, the team was able to characterize the performance of their new glass-based set-up, so that it can now be used as a reliable phase detector for few-cycle femtosecond laser pulses. The new instrument enormously simplifies measurements in the domain of ultrafast physical processes, because one can dispense with the use of cumbersome vacuum chambers. Moreover, in its practical application the technique is much more straightforward than the methods available for the mapping of waveforms hitherto.

If the precise waveform of the femtosecond laser pulse is known, it becomes possible to reproducibly generate stable trains of ultrashort attosecond light flashes, each one a thousand times shorter than the pulse used to induce them. The composition of the attosecond flashes is in turn highly dependent on the exact shape of the femtosecond pulses. Attosecond flashes can be used to “photograph” the motions of electrons in atoms or molecules. In order to obtain high-resolution images, the length of the flashes must be tuned to take account of the material one wants to investigate.

Highly sensitive and reliable measurements of physical processes at the level of the microcosmos with the aid of single attosecond light flashes of known shape should become easier to perform because, thanks to the new glass-based phase detector, the source of the energy to drive them – the waveform of the laser pulses – can now be controlled much more easily than before. Thorsten Naeser

Original publication:

Tim Paasch-Colberg, Agustin Schiffrin, Nicholas Karpowicz, Stanislav Kruchinin, Özge Saglam, Sabine Keiber, Olga Razskazovskaya, Sascha Mühlbrandt, Ali Alnaser, Matthias Kübel, Vadym Apalkov, Daniel Gerster, Joachim Reichert, Tibor Wittmann, Johannes V. Barth, Mark I. Stockman, Ralph Ernstorfer, Vladislav S. Yakovlev, Reinhard Kienberger and Ferenc Krausz
Solid-state light-phase detector
Nature Photonics, DOI:10.1038/nphoton.2013.348, 12 January 2014
For more information please contact:
Tim Paasch-Colberg
Max-Planck-Institute of Quantum Optics
Hans-Kopfermann-Straße 1, 85748 Garching, Germany
Phone: +49 (0)89 / 32 905 -651
E-mail: tim.paasch-colberg@mpq.mpg.de.de
Prof. Ferenc Krausz
Chair of Experimental Physics, Ludwig-Maximilians-Universität München
Laboratory for Attosecond Physics
Director at the Max-Planck-Institute of Quantum Optics
Hans-Kopfermann-Straße 1
85748 Garching, Germany
Phone: +49 (0)89 / 32 905 -600
E-mail: ferenc.krausz@mpq.mpg.de
Dr. Olivia Meyer-Streng
Press & Public Relations
Max-Planck-Institute of Quantum Optics
Hans-Kopfermann-Straße 1, 85748 Garching, Germany
Phone: +49 (0)89 / 32 905 -213
E-mail: olivia.meyer-streng@mpq.mpg.de

Dr. Olivia Meyer-Streng | Max-Planck-Institut
Further information:
http://www.attoworld.de
http://www.mpq.mpg.de

More articles from Physics and Astronomy:

nachricht Interstellar seeds could create oases of life
28.08.2015 | Harvard-Smithsonian Center for Astrophysics

nachricht Draw out of the predicted interatomic force
28.08.2015 | Hiroshima University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: OU astrophysicist and collaborators find supermassive black holes in quasar nearest Earth

A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.

The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...

Im Focus: What would a tsunami in the Mediterranean look like?

A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).

Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...

Im Focus: Self-healing landscape: landslides after earthquake

In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.

These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...

Im Focus: FIC Proteins Send Bacteria Into Hibernation

Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.

For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...

Im Focus: Fraunhofer IPA develops prototype of intelligent care cart

It comes when called, bringing care utensils with it and recording how they are used: Fraunhofer IPA is developing an intelligent care cart that provides care staff with physical and informational support in their day-to-day work. The scientists at Fraunhofer IPA have now completed a first prototype. In doing so, they are continuing in their efforts to improve working conditions in the care sector and are developing solutions designed to address the challenges of demographic change.

Technical assistance systems can improve the difficult working conditions in residential nursing homes and hospitals by helping the staff in their work and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Networking conference in Heidelberg for outstanding mathematicians and computer scientists

20.08.2015 | Event News

Scientists meet in Münster for the world’s largest Chitin und Chitosan Conference

20.08.2015 | Event News

Large agribusiness management strategies

19.08.2015 | Event News

 
Latest News

Interstellar seeds could create oases of life

28.08.2015 | Physics and Astronomy

An ounce of prevention: Research advances on 'scourge' of transplant wards

28.08.2015 | Health and Medicine

Fish Oil-Diet Benefits May be Mediated by Gut Microbes

28.08.2015 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>