University of Colorado professors conduct new laser research

  • Published
  • By Maria Callier
  • Air Force Office of Scientific Research
ARLINGTON, Va. --  A University of Colorado at Boulder husband and wife research team, Professor Margaret Murnane and Dr. Henry Kapteyn, have developed new, practical, laser-like sources in the ultraviolet and soft x-ray regions based on the most extreme form of nonlinear optics.

In this work, an intense femtosecond laser is focused into a gas-filled hollow waveguide. The interaction between the laser field and the atoms in the gas is so strong that electrons are violently accelerated and then liberate their energy as a coherent beam of x-rays.

Ultrafast coherent beams of x-rays have a myriad of applications in technology and science -- from next-generation microscopes that have the capability to image thick samples in 3-D, to understanding how heat flows in nanostructures or how electrons move at interfaces relevant to energy harvesting.

Murnane and Kapteyn established a student lab at CU--Boulder that pursues cutting-edge laser technologies, and their application in both science and technology. 

"Our research straddles the boundary between laser science and technology. We take ideas all the way from conception to integration in systems that can then be used by other scientists. This takes a team of physicists, engineers and chemists all working together, said Murnane."

This research impacts the Air Force by making ultrafast lasers useful in remote sensing, missile defense and adapted optics. The femtosecond lasers that the group develops to power the x-ray source are also used in micromachining and may be applied to aircraft aerodynamics and high-performance engines.

Murnane and Kapteyn are the first researchers to explore how atoms and molecules respond to light pulses. That work may lead to possible future technologies that use the high energy densities of lasers.

"We discovered that the interaction of atoms and molecules is both useful for making coherent x-rays, which in the future may image previously undetectable cracks in jet turbine blades. They are also helpful in uncovering electron dynamics at the 'attosecond' time scale domain," added Murnane.

A major future challenge is to find ways of generating coherent x-ray beams, which require the scientists to control quantum phenomena at very high laser intensities. The challenges have also yielded new demands on the technology the couple uses to meet their goals.

"After a number of years of exploiting the laser technology that we already developed, we are now planning a new push for high-power laser technologies," said Murnane.

Simultaneous to their research about new laser technologies, the couple is also celebrating an upcoming honor. In March 2009 in Salt Lake City, Utah, they will be presented the Ahmed Zewail Award in Ultrafast Science and Technology "for outstanding and creative contributions by a nominee to fundamental discoveries or inventions in ultrafast science and technology in the areas of physics, chemistry, biology or related fields without regard to age or nationality."

"We are thrilled and more than a bit surprised! And we very grateful because this is the first time we received a joint award. Given how important teamwork in our group, we were very thankful to ACS for allowing a joint award. This is a relatively new award, established in 2005. We are absolutely over the top proud to have our names associated with Ahmed Zewail - the 1999 chemistry Nobel laureate who originated the field of "femtochemistry," said Murnane.