High Aspect Ratio Nano-Pillars Fabricated by a Single Pulse of Ultrafast Bessel Beam

The interaction between laser and matter can efficiently produce very interesting structures. Despite the flexibility of the conventional Gaussian beam, other beam shapes bring advantages in matter structuring. Applying a conical phase, the Gaussian beam can be shaped in a zeroth order Bessel beam with its characteristic high aspect ratio central core. The Bessel beam gives interesting results in single shot drilling and fast-cutting of thick material [1], [2]. Moreover, by applying an additional vortex phase, a higher order Bessel beam is obtained with a hollow cylindrical central core. A single shot of this beam can create an elongated zone of higher density due to matter compression [3]. On the other side, a vortex phase on a gaussian beam gives a doughnut shaped beam carrying optical angular momentum that is capable of generating spiraling nano-needles [4].