Using computer simulations, researchers from the University of California and the University of Southern California, both in Los Angeles, have proposed a method to use the phenomenon of particle deceleration in underdense plasmas to generate nearly single-cycle laser pulses of a few femtoseconds in the optical to IR range with intensities greater than 1020 W/cm2.The method, which would be applicable with today's technology, relies on the interaction of relativistic mass nonlinearity and the laser wake field in a plasma. The cumulative effect is a faster frequency downshifting at the front of a laser pulse than at the back, which compresses the pulse while increasing its amplitude.The particle-in-cell simulations, which are described in the Jan. 8 issue of the Proceedings of the National Academy of Sciences, were executed using an object-oriented plasma-simulation code called Osiris.