GARCHING, Germany, June 15, 2012 — A new method that generates ultrashort attosecond bursts of light on a glass target will enable the highest resolution to date.
Currently, attosecond flashes of light are generated by electrons in noble gases. These atoms’ electrons absorb the laser light’s energy and subsequently emit it in the form of ultrashort flashes of light.
Attosecond flashes of light can be generated on a glass surface under the influence of strong laserpulses. Every laserpulse hitting surface leaves a punctual imprint on the glass surface and produces attosecond flashes of light. (Image: Thorsten Naeser)
Scientists at the Laboratory of Attosecond Physics at the Max Planck Institute of Quantum Optics have found an alternative way to generate these attopulses of light. They created an oscillating mirror of sorts by shooting an 8-fs laser pulse with a power of 16 terawatts onto a glass target.
The pulse consisted of three optical cycles, or three cycles of its electric field. The electrons at the surface were accelerated out of the solid to velocities close to the speed of light and subsequently decelerated and sent back to the surface as soon as the electric field changed its polarization. This generated an oscillating mirror.
The pulsed laser light was converted from the near-infrared to the extreme- ultraviolet spectrum during reflection in the mirror, generating shorter flashes of light with a duration in the attosecond regime. These flashes of light occur in isolated bursts if filtered appropriately. The scientists achieved durations of around 100 as.
In comparison to conventional attosecond pulse generation methods, the alternative technique delivers flashes of light that are more intense because they contain more photons. This higher intensity allows for the splitting of these isolated bursts into two attosecond flashes of light, enabling the observation of processes in microcosm.
The method appeared in Physical Review Letters
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