A step towards perfect control of light waves

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A team at the Laboratory for Attosecond Physics at the Max Planck Institute for Quantum Optics (MPQ) in Germany has developed a glass-based detector that can determine the form of light waves that make up an individual femtosecond pulse. The research, published in January’s issue of journal Nature Photonics, will allow researchers to generate light flashes that are a thousand times shorter to study ultrafast processes at the molecular and atomic levels.

In the course of experiments performed over the past several years, together with colleagues based at the Ludwig Maximilian University of Munich and the Technical University of Munich, physicists have learned that, when pulsed high-intensity laser light impinges on glass, it induces measurable amounts of electric current in the material. The glass detector created by the team is able to measure the flow of electric current between two electrodes 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.

If the precise waveform of the femtosecond laser pulse is known, it will become possible to reproducibly generate stable trains of ultrashort attosecond light flashes - which are highly dependent on the exact shape of the femtosecond pulse. 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 measurements of physical processes at the level of bacteria, viruses, atoms, and other particles using single attosecond light flashes will become easier to perform, because the new glass-based phase detector can now be controlled much more easily than before.