Tailored bam shaping techniques for enhanced ultrashort pulse laser processing

Resumen

Ultrashort pulse (USP) laser processing has set a new standard in the manufacturing industry due to its high precision and its capacity to engrave nearly all materials. This technology has been introduced in sectors such as automotive, aerospace and electronics for tasks such as micro-drilling or surface structuring. However, some challenges to the widespread use of USP laser processing include improving fabrication speed and exibility to meet industrial demands. Beam shaping techniques, which involves altering the amplitude, phase, or polarization of laser beams, have emerged as a convenient solution to address these issues, as they allow for more ecient, versatile, and high-resolution material processing. In this thesis, various beam shaping strategies are explored to boost the throughput and applicability of USP laser manufacturing processes. In particular, the experimental work is divided into three main parts, each focusing on a dierent type of beam shaping. The rst part investigates the optimization and application of Bessel beams for generating volume diraction gratings in dierent glasses. It includes the study of nonlinear laser-matter interactions during irradiation of each material and examines its eect on the morphological and optical properties of the resulting volume modications. By ne-tuning the laser writing parameters, ecient phase elements suitable for multiple applications are produced in all types of glass in a single laser pass. The second part examines the use of triangular beams to streamline asymmetrical surface machining. This novel manufacturing method was employed to engrave grooves with a wide range of geometries in a single step. Additionally, it enabled the straightforward fabrication of blazed gratings on stainless steel, with features similar to those manufactured using conventional methods. The third part focuses on the generation of multilevel at-top beams and its application in USP laser polishing. To optimize light structuring, several diractive optical elements (DOEs) were manufactured using a femtosecond (fs) laser-assisted lithographic process. The results of this line of work demonstrate the importance of the design and fabrication of the DOEs to ensure homogeneous beam shaping and uniform processing using an USP laser source. Overall, this thesis presents new strategies to enhance the precision and eciency of ultrashort pulse (USP) laser material processing. The ndings contribute to the broader eld of laser microfabrication and have clear implications in industrial applications.