Frontiers in ultrashort pulse generation: Pushing the limits in linear and nonlinear optics

Optical pulses in the 5-femtosecond range are produced by a variety of methods. Although different in technical detail, each method relies on the same three key components: spectral broadening due to the nonlinear optical Kerr effect, dispersion control, and ultrabroadband ampliÞcation. The state of the art of ultrashort pulse generation is reviewed with a focus on direct laser oscillator schemes. Our ability to perceive the dynamics of nature is ultimately limited by the temporal resolu-tion of the instruments available to us. Me-chanical shutters allow for resolution in the millisecond range, whereas stroboscopic illu-mination allows us to probe the microsecond range. Modern electronic sampling oscillo-scopes eventually brought the limit down into the picosecond range. Ultrafast lasers hav