Detecting the shape of laser pulses

May 17, 2018, Institute for Basic Science
Detecting the shape of laser pulses
Schematic diagram of TIPTOE technology.Special mirrors divide a laser beam into a strong (EF) and a weak (ES) laser pulses. When the laser beams reach the air or gas-filled chamber, electrons escape from their atoms (tunnel ionization) and are caught by the metal plates. Changes in ionization are used to measure the shape of the laser pulse. Credit: Institute for Basic Science

A team of researchers at the Center for Relativistic Laser Science, within the Institute for Basic Science (IBS) have developed a method to measure the shape of laser pulses in ambient air. Unlike conventional strategies, it is does not require a vacuum environment and can be applied to laser beams of different wavelengths (UV, visible or longer). This patented technique, currently available for technology transfer and commercialization, has now been published in Optica, and it is expected to accelerate studies on light-matter interaction.

Experts aim to employ light to control the behavior of the electrons, and potentially to manipulate electric currents. However, in order to reach these goals, it is essential to know the waveform of a laser pulse. As molecular events occur in just attoseconds (1 as = 10-18 seconds), the existing method to study them relies on the generation of attosecond X-ray pulses which requires detection equipment in vacuum chambers. IBS researchers devised an alternative approach called TIPTOE (tunneling ionization with a perturbation for the time-domain observation of an electric ) which needs neither X-rays pulses nor vacuum conditions.

TIPTOE is based on two superimposed laser pulses: a strong one and a weak one. Atoms or molecules exposed to intensive electric fields, like the ones created by strong laser pulses, can lose some of their electrons in a phenomenon called tunnel ionization. The TIPTOE method depends on the intensity of the electric field and the tunnel ionization of the electrons of the atoms in the air. Time differences between the strong and the weak superimposed cause the electric field intensity to vary. As a higher electric field intensity corresponds to higher ionization, changes in the are directly reflected on the tunnel ionization. And in turn, these changes in tunnel ionization are used to measure the shape of the laser pulse. Since tunneling lasts only 200 attoseconds, the TIPTOE method can provide enough temporal resolution to measure UV, visible, and longer wavelength pules.

Detecting the shape of laser pulses
Comparison between attosecond X-ray pulse method X-ray (blue) and TIPTOE (red) to validate the new technique developed by IBS scientists. The waveforms measured with TIPTOE match the ones obtained with the conventional method. Credit: Institute for Basic Science

IBS scientists validated TIPTOE by comparing it with the conventional X-ray generation technique, and the results were the same.

"TIPTOE's biggest advantage is the universality of this technique at different wavelengths," explains Kyung Taec Kim, the leading author of this study.

Explore further: Processes in the atomic microcosmos revealed

More information: Seung Beom Park et al. Direct sampling of a light wave in air, Optica (2018). DOI: 10.1364/OPTICA.5.000402 Seung Beom Park et al. Direct sampling of a light wave in air, Optica (2018). DOI: 10.1364/OPTICA.5.000402

Related Stories

Processes in the atomic microcosmos revealed

May 16, 2018

Physicists at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have successfully generated controlled electron pulses in the attosecond range. They used optical traveling waves formed by laser pulses of varying wavelengths. ...

Hard X-ray flash breaks speed record

April 10, 2018

Reactions in solar panels, catalytic converters, and other devices are governed by the quick motion of electrons. To capture the movement of these electrons, scientists use pulses of extremely high energy x-rays. The challenge ...

Looking at complex light wave forms

May 31, 2017

For the first time, an international research team under the direction of Prof. Dr. Giuseppe Sansone at the Institute of Physics at the University of Freiburg has been able to completely characterize the complex evolution ...

Recommended for you

How heavy elements come about in the universe

March 19, 2019

Heavy elements are produced during stellar explosion or on the surfaces of neutron stars through the capture of hydrogen nuclei (protons). This occurs at extremely high temperatures, but at relatively low energies. An international ...

Trembling aspen leaves could save future Mars rovers

March 18, 2019

Researchers at the University of Warwick have been inspired by the unique movement of trembling aspen leaves, to devise an energy harvesting mechanism that could power weather sensors in hostile environments and could even ...

Quantum sensing method measures minuscule magnetic fields

March 15, 2019

A new way of measuring atomic-scale magnetic fields with great precision, not only up and down but sideways as well, has been developed by researchers at MIT. The new tool could be useful in applications as diverse as mapping ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.