Single-Step Fabrication of Highly Tunable Blazed Gratings Using Triangular-Shaped Femtosecond Laser Pulses.

Blazed gratings are periodic surface structures of great interest for applications such as friction control, light trapping, and spectrometry. While different laser processing methods have been explored to produce these elements, they have not yet surpassed conventional surface manufacturing techniques, often based on lithography processes or mechanical ruling. This work introduces a new approach based on the combination of ultrashort pulses and triangular beam shaping, which enables the generation of asymmetrical grooves in a single step. The main advantage of this strategy is that by simply changing the laser processing direction we can induce a significant modification in the ratio of asymmetry between the sidewall angles of the machined channels. The paper includes a comprehensive study, which has been supported by statistical tools, of the effect of this and other experimental parameters on the morphology of grooves machined on stainless steel. As a result, we achieved a wide range of geometries, with asymmetry ratios spanning from 1 to 5 and channel depths between 3 and 15 µm. Furthermore, we demonstrate the validity of the approach through the successful manufacture of blazed gratings of various slopes. The results reflect the versatility and cost-efficiency of the proposed fabrication strategy, and thus its potential to streamline the production of sawtooth gratings and other devices that are based on asymmetrical features.

Fabrication of Thin-Wall Structures with a Femtosecond Laser and Stainless Steel Powder.

Additive Manufacturing (AM) has revolutionized the production of complex three-dimensional (3D) structures; however, the efficient and precise fabrication of thin profiles remains a challenge. This study explores the application of femtosecond-laser-based additive manufacturing techniques for the production of thin profiles with micron-scale features, reaching profile thicknesses below 100 µm. The study investigates the effects of scanning strategy, with optimized processing parameters, on the fabrication of thin profiles; wall thickness measurements were carried out using various technologies to analyse the influence of each on the resulting values. The quality of the walls was quantified by means of a visual characterization of the melted volumes, analysing the evolution of the measured thickness with regard to the processing conditions and in relation to the theoretical thicknesses of the walls.