Abstract

When a laser beam is focused by a conical lens, it generates a Bessel filament in the focal region, i.e. a light string with a narrow core over a distance that may slightly exceed the Bessel zone. In the stationary regime characterized by a uniform light channel over the Bessel zone with a quasi-constant intensity, the laser pulse leaves in its wake a uniform plasma track which is essential for an efficient microfabrication of transparent materials. This plasma track is indeed the main support for laser energy deposition, before energy is transferred to the lattice and induces thermo-mechanical constraints leading to void nanochannels or to high aspect ratio inscribed microstructures [1]. In general, plasma imaging techniques (either time-integrated or time-resolved) provide a unique tool that has been used for long for the assessment of ultrafast interactions. They are usually holographic reconstructions techniques that make use of a pump and an orthogonally propagating probe [2,3].

© 2015 IEEE