An international team of physicists from the University of Kassel, led by Prof. Thomas Baumert, and the University of Aarhus, led by Prof. Peter Balling, discovered that ultra-short laser pulses are amplified in a laser excited piece of glass. This amplification, similar to a classical laser, is directed and of coherent nature. By utilizing theoretical models and simulations, the researchers were able to understand and reproduce the multi-step process leading to the “Laser Amplification in Excited Dielectrics” (short: LADIE) named effect. Their results were published online in the well-known research journal Nature Physics.
If a transparent dielectric material like water or glass is illuminated by visible or infrared light it is transmitted without loss. This quickly changes if ultra-short laser pulses on the femtosecond timescale (quadrillionth second) are used:
Caused by the high intensities that such laser pulses provide, different interaction mechanisms are able to transfer the transparent material into a metallic like state. The created “free” electrons, similar to a metal, play a significant role in the change of the optical properties associated to the excitation of the material.
Accordingly, pump-probe experiments, utilizing two temporally delayed laser pulses were proven to be a very useful method to investigate the laser-material interaction. Indeed, most experiments show that shortly after the laser excitation, absorption and reflection increase due to the creation of high density of free electrons giving the dielectric material transient metallic properties.
Researchers from the Experimental Physics III located at the University of Kassel, in cooperation with colleagues from the Department of Physics at the University of Aarhus in Denmark, recently performed similar experiments on laser excited sapphire glass.
Much to their surprise, the researchers observed that the absorption of a violet probe pulse is, under certain conditions, replaced by coherent amplification. The physicists could link the observed amplification to the, so far, unobserved LADIE mechanism. While in typical light amplification processes, such as a laser, single photons are doubled, the study suggests that the LADIE process provides a multi photon process, for example making four out of two incident photons.
“It is too early to foresee possible impacts or applications of the LADIE effect”, says Thomas Winkler, scientist at the Kassel Department of Physics. “Yet it provides a more detailed understanding of the light material interaction. However, also the discovery of the LASER in the mid 60s by Theodore Maiman was an unusual discovery that was initially seen as no more than another thrilling aspect of quantum physics. However, today, more than 50 years later, there are no products or technical process in which laser-technology is not involved in a certain way.”
The publication was published on Monday, 18th September 2017 and is available under the following link: https://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys4265.html
For a picture (copyright: Uni Kassel), please see: https://www.uni-kassel.de/uni/fileadmin/datas/uni/presse/anhaenge/2017/NatPhysic...
Institut für Physik
Tel.: +49 561 804 4319
Prof. Dr. Thomas Baumert
Institut für Physik
Tel: +49 561 804 4452
Sebastian Mense | idw - Informationsdienst Wissenschaft
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences