Femtosecond Experts: Fast Is Fun

Research at the very edge of the time scale for laser pulses is becoming more exciting, according to two ultrafast-laser experts who shared the Schawlow Prize (and lecture) at the American Physical Society's Interdisciplinary Laser Science Conference in Long Beach, Calif., last month.
Erich Ippin, a professor at the Massachusetts Institute of Technology in Cambridge, Mass., cited some recent results in the area of ultrafast lasers, including a Vienna/Milan team that pushed a Ti:sapphire laser to produce a pulse that is the equivalent of only two cycles of light. He said researchers will need to produce some phase-dependent nonlinear optics to reduce the pulse by a great deal, but he thinks "there is fun work to do off the bottom of the scale."
One of the aims of ultrafast laser research is to produce an x-ray light source that can look deep into the atom at extremely high spatial and temporal resolution to see its structure and answer questions about nuclear positions. Research at the Lawrence Berkeley National Laboratory has produced a 300-fs x-ray source. Charles Shank said the group is colliding extremely high energy electrons from a linear accelerator with photons to generate 10⁵ x-ray photons per 300-fs pulse.