Axiparabola: a long-focal-depth, high-resolution mirror for broadband high-intensity lasers.

Diffraction puts a fundamental limit on the distance over which a light beam can remain focused. For about 30 years, several techniques to overcome this limit have been demonstrated. Here, we propose a reflective optics, namely, the axiparabola, that allows to extend the production of "diffraction-free" beams to high-peak-power and broadband laser pulses. We first describe the properties of this aspheric optics. We then analyze and compare its performances in numerical simulations and in experiments. Finally, we use it to produce a plasma waveguide that can guide an intense laser pulse over 10 millimeters.