Producing isolated laser pulses in attoseconds made easier using two-color laser field

Aug 30, 2010
Figure 1: An artistic representation of light from two lasers. Conventional, two-color infrared laser beams can be used simply and reliably in systems designed to produce attosecond laser pulses. © 2010 iStockphoto/RapidEye

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 pulses reliably is challenging. Commonly, physicists use few-cycle with a near 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, Japan, 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 reliability.

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 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.

Explore further: New technique detects microscopic diabetes-related eye damage

More information: 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).

add to favorites email to friend print save as pdf

Related Stories

K-State attosecond research could aid Homeland Security

May 21, 2007

Building a new laser-like X-ray source powerful and quick enough to capture fast motion in the atomic world is a big job. But Zenghu Chang, Kansas State University professor of physics, and his team of physicists and engineers ...

Scientists track electrons in molecules

Jun 13, 2010

( -- Physicists in Europe have successfully glimpsed the motion of electrons in molecules. The results are a major boon for the research world. Knowing how electrons move within molecules will ...

Recommended for you

Robotics goes micro-scale

23 hours ago

( —The development of light-driven 'micro-robots' that can autonomously investigate and manipulate the nano-scale environment in a microscope comes a step closer, thanks to new research from the ...

High power laser sources at exotic wavelengths

Apr 14, 2014

High power laser sources at exotic wavelengths may be a step closer as researchers in China report a fibre optic parametric oscillator with record breaking efficiency. The research team believe this could ...

Combs of light accelerate communication

Apr 14, 2014

Miniaturized optical frequency comb sources allow for transmission of data streams of several terabits per second over hundreds of kilometers – this has now been demonstrated by researchers of Karlsruhe ...

User comments : 0

More news stories

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

Robotics goes micro-scale

( —The development of light-driven 'micro-robots' that can autonomously investigate and manipulate the nano-scale environment in a microscope comes a step closer, thanks to new research from the ...

Leeches help save woman's ear after pit bull mauling

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

White House updating online privacy policy

A new Obama administration privacy policy out Friday explains how the government will gather the user data of online visitors to, mobile apps and social media sites. It also clarifies that ...