Ultrafast time-resolved laser spectroscopy is a technique that uses the interaction of light with matter to study the properties of physical systems. Researchers can generate laser pulses lasting mere attoseconds—quintillionths of seconds—to examine the nuclear dynamics in different states of matter, including single atoms.
Generating isolated attosecond pulses reliably is challenging. Commonly, physicists use few-cycle laser pulses with a near infrared wavelength as a pump to temporarily ionize specific atoms, typically those of a noble gas. When an electron re-collides with a nucleus from which it has been pulled away, it emits light with a much higher frequency than the one in the pump laser. This so-called ‘high-order harmonic generation’ usually in the extreme ultraviolet region can create an attosecond pulse.
Eiji Takahashi and his colleagues at the RIKEN Advanced Science Institute in Wako, in collaboration with scientists at the Vienna University of Technology, Austria, have now reported a way to easily produce isolated attosecond pulses, which surpasses all previous attempts for simplicity and reliability1.
A number of research groups have recently generated isolated laser pulses as short as 80 attoseconds. However, their energy is still too low be used in practice, since the energy of the pump pulses is limited. High pump energy would induce high gas ionization such that the atoms hit by the pump pulses would be highly ionized, but this would prevent the whole process of re-collision. In addition, to guarantee reliable production of isolated attosecond pulses, the phase of the carrier envelope wave connected to the pump pulse needs to be stabilized, which requires an expensive and complicated process.
To circumvent these limitations, Takahashi and colleagues used a two-color laser field: a pump laser with an 800-nanometer wavelength superimposed on one of 1,300 nanometers. The combination of the two lasers allowed the generation of a higher harmonic spectrum without needing to stabilize the carrier envelope phase.
Crucially, they used conventional lasers that are readily available and inexpensive. “This novel two-color laser scheme also enables one to markedly suppress the detrimental gas target ionization,” notes Takahashi. “Consequently, not only the most appropriate phase-matching technique, but also an energy-scaling scheme, can be applied to produce intense isolated attosecond pulses.”
Takahashi also says that this method has the potential to produce isolated, attosecond, extreme-ultraviolet x-ray pulses with microjoule energy from a table-top system. He believes this would open the door to the realm of strongly nonlinear attosecond science.
The corresponding author for this highlight is based at the Extreme Photonics Research Group, RIKEN Advanced Science Institute.
1. Takahashi, E.J., Lan, P., Mücke, O.D., Nabekawa, Y. & Midorikawa, K. Infrared two-color multicycle laser-field synthesis for generating an intense attosecond pulse. Physical Review Letters 104, 233901 (2010).
gro-pr | Research asia research news
CeGlaFlex project: wafer-thin, unbreakable and flexible ceramic and glass
25.04.2017 | Fraunhofer-Institut für Lasertechnik ILT
Additive manufacturing, from macro to nano
11.04.2017 | Laser Zentrum Hannover e.V.
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
26.04.2017 | Materials Sciences
26.04.2017 | Agricultural and Forestry Science
26.04.2017 | Physics and Astronomy