Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Laserphysics: At the pulse of a light wave

13.01.2020

Physicists in the Laboratory for Attosecond Physics at Ludwig-Maximilians-Universitaet (LMU) in Munich and at the Max Planck Institute for Quantum Optics (MPQ) have developed a novel type of detector that enables the oscillation profile of light waves to be precisely determined.

Light is hard to get a hold on. Light waves propagate with a velocity of almost 300,000 km per second, and the wavefront oscillates several hundred trillion times in that same interval.


How a novel type of detector enables the oscillation profile of light waves to be precisely determined.

Picture: Philipp Rosenberger

In the case of visible light, the physical distance between successive peaks of the light wave is less than 1 micrometer, and peaks are separated in time by less than 3 millionths of a billionth of a second (<3 femtoseconds). To work with light, one must control it - and that requires precise knowledge of its behaviour.

It may even be necessary to know the exact position of the crests or valleys of the light wave at a given instant. Researchers based at the Laboratory for Attosecond Physics (LAP) (at the LMU Munich and the Max Planck Institute for Quantum Optics) are now in a position to measure the exact location of such peaks within single ultrashort pulses of infrared light with the aid of a newly developed detector.

Such pulses, which encompass only a few oscillations of the wave, can be used to investigate the behaviour of molecules and their constituent atoms, and the new detector is a very valuable tool in this context. Ultrashort laser pulses allow scientists to study dynamic processes at molecular and even subatomic levels.

Using trains of these pulses, it is possible first to excite the target particles and then to film their responses in real time. In intense light fields, however, it is crucial to know the precise waveform of the pulses.

Since the peak of the oscillating (carrier) light field and that of the pulse envelope can shift with respect to each other between different laser pulses, it is important to know the precise waveform of each pulse.

The team at LAP, which was led by Dr. Boris Bergues and Professor Matthias Kling, head of the Ultrafast Imaging and Nanophotonics Group, has now made a decisive breakthrough in the characterization of light waves.

Their new detector allows them to determine the 'phase', i.e. the precise positions of the peaks of the few oscillation cycles within each and every pulse, at repetition rates of 10,000 pulses per second.

To do so, the group generated circularly polarized laser pulses in which the orientation of the propagating optical field rotates like a clock hand, and then focused the rotating pulse in ambient air.

The interaction between the pulse and molecules in the air results in a short burst of electric current, whose direction depends on the position of the peak of the light wave. By analyzing the exact direction of the current pulse, the researchers were able to retrieve the phase of the „carrier-envelope offset", and thus reconstruct the form of the light wave.

Unlike the method conventionally employed for phase determination, which requires the use of a complex vacuum apparatus, the new technique works in ambient air and the measurements require very few extra components. „The simplicity of the setup is likely to ensure that it will become a standard tool in laser technology", explains Matthias Kling.

„We believe that this technique can also be applied to lasers with much higher repetition rates and in different spectral regions," says Boris Bergues. „Our methodology is of particular interest in the context of the characterization of extremely short laser pulses with high repetition rates, such as those generated at Europe's Extreme Light Infrastructure (ELI)," adds Prof. Matthias Kling.

When applied to the latest sources of ultrashort laser pulses, this new method of waveform analysis could pave the way to technological breakthroughs, as well as permitting new insights into the behaviour of elementary particles 'in the fast lane'.

Media Contact

Dr. Kathrin Bilgeri
presse@lmu.de
49-892-180-3423

http://www.uni-muenchen.de 

Dr. Kathrin Bilgeri | EurekAlert!
Further information:
https://www.en.uni-muenchen.de/news/newsarchiv/2020/kling_lightwave.html
http://dx.doi.org/10.1364/OPTICA.7.000035

More articles from Physics and Astronomy:

nachricht Silicon 'neurons' may add a new dimension to computer processors
05.06.2020 | Washington University in St. Louis

nachricht The broken mirror: Can parity violation in molecules finally be measured?
04.06.2020 | Johannes Gutenberg-Universität Mainz

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: Restoring vision by gene therapy

Latest scientific findings give hope for people with incurable retinal degeneration

Humans rely dominantly on their eyesight. Losing vision means not being able to read, recognize faces or find objects. Macular degeneration is one of the major...

Im Focus: Small Protein, Big Impact

In meningococci, the RNA-binding protein ProQ plays a major role. Together with RNA molecules, it regulates processes that are important for pathogenic properties of the bacteria.

Meningococci are bacteria that can cause life-threatening meningitis and sepsis. These pathogens use a small protein with a large impact: The RNA-binding...

Im Focus: K-State study reveals asymmetry in spin directions of galaxies

Research also suggests the early universe could have been spinning

An analysis of more than 200,000 spiral galaxies has revealed unexpected links between spin directions of galaxies, and the structure formed by these links...

Im Focus: New measurement exacerbates old problem

Two prominent X-ray emission lines of highly charged iron have puzzled astrophysicists for decades: their measured and calculated brightness ratios always disagree. This hinders good determinations of plasma temperatures and densities. New, careful high-precision measurements, together with top-level calculations now exclude all hitherto proposed explanations for this discrepancy, and thus deepen the problem.

Hot astrophysical plasmas fill the intergalactic space, and brightly shine in stellar coronae, active galactic nuclei, and supernova remnants. They contain...

Im Focus: Biotechnology: Triggered by light, a novel way to switch on an enzyme

In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".

Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

 
Latest News

New image of a cancer-related enzyme in action helps explain gene regulation

05.06.2020 | Life Sciences

Silicon 'neurons' may add a new dimension to computer processors

05.06.2020 | Physics and Astronomy

Protecting the Neuronal Architecture

05.06.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>