Amplification Concept Simplifies Ultrafast Lasers

Ultrafast lasers operate at the physical limits of optical materials. This has long set limits on molecular imaging, which requires short, powerful light pulses.

A team from the Energy Materials Telecommunications Research Center at the Canadian National Institute for Scientific Research (INRS) has developed a way to overcome such limitations, with a simpler laser design and better control over the parameters.

The concept, called Frequency Domain Optical Parametric Amplification (FOPA), replaces traditional time domain amplification schemes that have long been the cornerstone of ultrafast laser science, said lead researcher François Légaré, a professor at the INRS research center.

Amplifying laser pulses in the frequency domain instead of the time domain can overcome technical constraints, which includes the ability to access multiple frequencies simultaneously while controlling them independently, researchers said. The researchers have also demonstrated that higher light pulse energy can be achieved with their new concept.

“Our approach holds promise for high-power, broad-spectrum, few-cycle laser sources,” Légaré said. “Our goal is to capture images of a chemical reaction using high spatial and temporal resolution.”

In the study, FOPA was shown to open access to parameters that previously could not be controlled and also to eliminate many complex assembly components. The potential also exists to generate single-cycle, multi-terawatt laser pulses, researchers said.

Fundamental restrictions with nonlinear lasers, such as low-efficiency phase mismatch and low-power damage threshold, can also be averted with the new concept.

“We believe [the new concept] will allow us to look at nonlinear optics in a whole new light,” said INRS researcher Bruno Schmidt.

The work was funded by the Natural Sciences and Engineering Research Council of Canada, the Canadian Institute for Photonic Innovations, the Quebec Nature and Technology Research Fund, Quebec’s Ministry of Economic Development, Innovation and Export, and DARPA PULSE (the Defense Advanced Research Projects Agency’s Program in Ultrafast Laser Science and Engineering). The research is published in Nature Communications (doi: 10.1038/ncomms4643).

For more information, visit www.inrs.ca.