Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New light at the end of the tunnel

17.10.2011
An international team of scientists successfully concentrated the energy of infrared laser pulses using a nano funnel enabling them to generate extreme ultraviolet light pulses, which repeated 75 million times per second.

Who wants to decant liquids in the kitchen without spilling knows to value a funnel. Funnels are not only useful tools in the kitchen. Light can also be efficiently concentrated with funnels. In this case, the funnels have to be about 10.000-times smaller.


Figure caption: Scheme of the generation of EUV light by the 3D nano funnel. The infrared light (shown in red) is incident at the entrance of the Xe (green depicted particles) filled nano funnel (shown as a half-cut). The surface plasmon polariton fields (wave pattern) concentrate near the tip of the structure. Extreme ultraviolet light (shown in purple) is generated in the enhanced fields in Xe and exits the funnel through the small opening, while the infrared light cannot penetrate the small opening and is back-reflected. Picture: Christian Hackenberger

An international team of scientists from the Korea Advanced Institute of Science and Technology (KAIST) in Daejeon (South Korea), the Max Planck Institute of Quantum Optics (MPQ) in Garching (Germany), and the Georgia State University (GSU) in Atlanta (USA) has now managed to concentrate the energy of infrared light pulses with a nano funnel and use the concentrated energy to generate extreme ultraviolet light flashes. These flashes, which repeated 75 million times per second, lasted only a few femtoseconds. The new technology can help in the future to measure the movement of electrons with the highest spatial and temporal resolution (Nature Photonics, 16.10.2011).

Light is convertible. The wavelengths composing the light can change through interactions with matter, where both the type of material and shape of the material are important for the frequency conversion. An international team of scientists from the Korea Advanced Institute of Science and Technology (KAIST), the Max Planck Institute of Quantum Optics (MPQ), and the Georgia State University (GSU) has now modified light waves with a nano funnel made out of silver. The scientists converted femtosecond laser pulses in the infrared spectral range to femtosecond light flashes in the extreme ultraviolet (EUV). Ultrashort, pulsed EUV light is used in laser physics to explore the inside of atoms and molecules. A femtosecond lasts only a millionth of a billionth of a second.

Light in the infrared (IR) can be converted to the EUV by a process known as high-harmonic generation, whereby the atoms are exposed to a strong electric field from the IR laser pulses. These fields have to be as strong as the fields holding the atom together. With these fields electrons can be extracted from the atoms and accelerated with full force back onto the atoms. Upon impact highly energetic radiation in the EUV is generated.

To reach the necessary strong electric fields for the production of EUV light, the team of scientists has now combined this scheme with a nano funnel in order to concentrate the electric field of the light. With their new technology, they were able to create a powerful EUV light source with wavelengths down to 20 nanometers. The light source exhibits a so far unreached high repetition rate: the few femtoseconds lasting EUV light flashes are repeated 75 million times per second.

The core of the experiment was a small, only a few micrometers long, slightly elliptical funnel made out of silver and filled with xenon gas (see Fig. 1). The tip of the funnel was only ca. 100 nanometers wide. The infrared light pulses were sent into the funnel entrance where they travel through towards the small exit. The electromagnetic forces of the light result in density fluctuations of the electrons on the inside of the funnel. Here, a small patch of the metal surface was positively charged, the next one negative and so on, resulting in new electromagnetic fields on the inside of the funnel, which are called surface plasmon polaritons. The surface plasmon polaritons travel towards the tip of the funnel, where the conical shape of the funnel results in a concentration of their fields. “The field on the inside of the funnel can become a few hundred times stronger than the field of the incident infrared light. This enhanced field results in the generation of EUV light in the Xe gas.”, explains Prof. Mark Stockman from GSU.

The nano funnel has yet another function. Its small opening at the exit acts as “doorman” for light wavelengths. Not every opening is passable for light. If the opening is smaller than half of a wavelength, the other side remains dark. The 100 nanometer large opening of the funnel did not allow the infrared light at 800 nm to pass. The generated EUV pulses with wavelengths down to 20 nanometers passed, however, without problems. “The funnel acts as an efficient wavelength filter: at the small opening only EUV light comes out.”, explains Prof. Seung-Woo Kim from KAIST, where the experiments were conducted.

“Due to their short wavelength and potentially short pulse duration reaching into the attosecond domain, extreme ultraviolet light pulses are an important tool for the exploration of electron dynamics in atoms, molecules and solids”, explains Seung-Woo Kim. Electrons are extremely fast, moving on attosecond timescales (an attosecond is a billionth of a billionth of a second). In order to capture a moving electron, light flashes are needed, which are shorter than the timescale of the motion. Attosecond light flashes have become a familiar tool in the exploration of electron motion. With the conventional techniques, they can only be repeated a few thousand times per second. This can change with the nano funnel. “We assume that the few femtosecond light flashes consist of trains of attosecond pulses”, argues Matthias Kling, group leader at MPQ. “With such pulse trains, we should be able to conduct experiments with attosecond time resolution at very high repetition rate.”

The repetition rate is important for e.g. the application of EUV pulses in electron spectroscopy on surfaces. Electrons repel each other by Coulomb forces. Therefore, it may be necessary to restrict the experimental conditions such that only a single electron is generated per laser shot. With low repetition rates, long data acquisition times would be required in order to achieve sufficient experimental resolution. “In order to conduct experiments with high spatial and temporal resolution within a sufficiently short time, a high repetition rate EUV source is needed”, explains Kling. The novel combination of laser technology and nanotechnology can help in the future to record movies of ultrafast electron motion on surfaces with so far unreached temporal and spatial resolution in the attosecond-nanometer domain. [Thorsten Naeser]

Publication:
In-Yong Park, Seungchul Kim, Joonhee Choi, Dong-Hyub Lee, Young-Jin Kim, Matthias F. Kling, Mark I. Stockman & Seung-Woo Kim
Plasmonic generation of ultrashort extreme-ultraviolet light pulses
Nature Photonics, 16 October 2011, Doi: 10.1038/NPHOTON.2011.258
Further information on attosecond physics:
http://www.attoworld.de
Contact information:
Prof. Seung-Woo Kim
Department of Mechanical Engineering
Korea Advanced Institute of Science and Technology
Science Town, Daejeon 305-701, South Korea
Phone: +82-42-869-3001, 3217
Fax: +82-42-869-3210
E-mail: swk@kaist.ac.kr
Website: http://pem.kaist.ac.kr/
Prof. Dr. Matthias Kling
Max Planck Institute of Quantum Optics
Max Planck Research Group „Attosecond Imaging“
Hans-Kopfermann-Str. 1, 85748 Garching, Germany
Phone: +49-89-32905-234
Fax: +49-89-32905-649
E-mail: matthias.kling@mpq.mpg.de
Website: http://www.attoworld.de/kling-group/
Prof. Mark Stockman
Department of Physics and Astronomy
Georgia State University
29 Peachtree Center Avenue, Science Annex, Suite 400
Atlanta, GA 30302, USA
Phone: +1-678-457-4739
Fax: +1-404-413-6025
E-mail: mstockman@gsu.edu
Website: http://www.phy-astr.gsu.edu/stockman
Dr. Olivia Meyer-Streng
Press and Public Relations
Max Planck Institute of Quantum Optics
Phone: +49 - 89 / 32905 - 213
E-mail: olivia.meyer-streng@mpq.mpg.de

Dr. Olivia Meyer-Streng | Max-Planck-Institut
Further information:
http://www.mpq.mpg.de

More articles from Physics and Astronomy:

nachricht Applicability of dynamic facilitation theory to binary hard disk systems
08.12.2016 | Nagoya Institute of Technology

nachricht Will Earth still exist 5 billion years from now?
08.12.2016 | KU Leuven

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>