Abstract: Our invention achieves spectral broadening of an input pulse by propagating it through a hollow fiber filled with a noble gas. The output pulse is then compressed to a shorter duration by passing it through an optical system consisting of phase dispersive elements. In a preferred embodiment, the input pulse is generated by a mode-locked laser, amplified and then subsequently compressed to produce an input pulse of high peak power. This input pulse is then focused into a hollow cylindrical fiber made of fused silica and mounted inside a pressure vessel filled with noble gas. The optics are designed to match the spatial mode volume of the input pulse to that of the entrance aperture of the hollow fiber. Light is constrained to propagate down the hollow fiber and generates additional bandwidth through self-phase modulation as it interacts with the gas contained therein. The spectrum of the pulse after propagation through the gas is frequency chirped.