Researchers Generate New Approach To Working With Laser Light

The researchers were able to synchronize two independent femtosecond lasers – lasers that generate light pulses with durations as short as 100 trillionth of a second– and phase lock the respective electric fields underneath the pulse envelopes to generate a single pulse of light that exhibits the properties of both lasers simultaneously.

"By combining the two lasers so precisely, we can create new shapes of light pulses that could not be created by either laser individually," said lead author Robert Shelton, a professional research assistant at JILA, a joint program of the University of Colorado at Boulder and the National Institute of Standards and Technology, who completed the work in the lab of Jun Ye.

"This is similar to taking two musical instruments and combining them to make an instrument with a totally new sound," Shelton said.

A paper on the subject by Robert Shelton, Long-Sheng Ma, Henry Kapteyn, Margaret Murnane, John Hall and Jun Ye of JILA appears in the Aug. 17 issue of the journal Science.

Ultrafast lasers, or femtosecond lasers, act as an "ultrafast light switch" similar to a strobe light, only the pulses of light from the laser are many orders of magnitude shorter than the strobe, Shelton said. Scientists use these flashes of laser light to freeze the motion of events that occur in atoms and molecules.

The interaction of coherent light with atoms and molecules, and the "control" of atoms and molecules has been a prominent scientific theme in recent years, he said. Being able to combine the characteristics of two or more pulsed lasers working at different colors will give scientists a more flexible approach in their work with light and matter.

The group’s work was accomplished by the successful merger of pulsed laser technology pioneered by researchers Murnane and Kapteyn and frequency domain laser control techniques developed by Hall and Ye. The past 10 years has seen a revolution in laser technology, with lasers now enabling scientists to have much greater control over light at ultrafast time scales, according to Ye.

"One of our goals is to use these lasers to ultimately be able to control molecules and atoms, which would have applications in many different areas," Murnane said of the developing laser technology.

Stabilized femtosecond laser pulses have made possible an unanticipated route for connecting radio and optical frequency spectral regions, according to Hall.

"This discovery is a super example of what can happen when high-level researchers can contribute across an interdisciplinary boundary," Hall said.

NIST is an agency of the U.S. Commerce Department’s Technology Administration.