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.

Abstract: Laser apparatus which generates a uniform laser beam of minimum divergence and maximum intensity includes a resonator cavity having a laser source and first and second mirror devices disposed on opposite sides of the source. The first mirror reflects pumped laser light within the cavity. The second mirror includes two mirror elements, both of which also reflect pumped laser light within the cavity. The two mirror elements of the second mirror device have specific configurations and a selected distance therebetween to cause the generation of a uniform output laser beam. That is, the laser light reflected from the second mirror element is dephased with respect to laser light reflected from the first mirror element by a whole number of periods of the laser light at the centerline between the first and second mirror elements.