Micromachining of quartz presents significant challenges due to its chemical inertness, high melting point and optical properties. Usually, structuring processes such as lithography in combination with wet chemical etching or RIE etching are used. These allow a high processing quality, but the variety of possible geometries is severely limited by the 2D pattern transfer. Conventional techniques such as micro-grinding and milling are limited to larger dimensions. Excimer lasers, emitting ns-pulses in the UV, enable high-quality microstructures but are mostly used for surface texturing or realization of simpler geometries due to beam characteristics. The third harmonic of a femtosecond laser (fs) offers precise processing with minimal thermal effects, allowing direct writing. This work demonstrates the fabrication of a complex quartz platform, providing experimental insights into cutting and structuring. The findings highlight the viability of femtosecond laser technology for high-quality micromachining of quartz platforms in advanced applications.

Transparent materials, such as glass and crystalline substances, are essential for optical interfaces in many technical and medical applications. The integration often requires the connection of the glasses with a metal structure. Established technologies such as adhesive or anodic bonding require a large contact area to achieve sufficient strength. Ultra Short Pulse (USP) laser welding can overcome these difficulties and offers precise, low-thermal impact joining of glass to metals without an intermediate bonding material.

Our previous studies have shown promising results, achieving average shear strengths over 50 MPa for glass to aluminum foil bonding. Here, we will discuss transferring our robust welding process to various metal foil combinations, extending the benefits of USP laser welding. Our findings suggest our approach can be adapted to a wide range of materials, opening new possibilities for industrial and medical applications requiring durable and precise assemblies.

The GHz-burst femtosecond laser regime has attracted growing interest for its applications in glass percussion drilling. In this work, we introduce an innovative GHz-burst femtosecond laser (800fs, burst energy >0.3mJ) ) operating at a green wavelength (515 nm), uniquely capable of generating arbitrary burst shapes. This advanced laser system unlocks new opportunities for optimizing ablation processes in glass percussion drilling. By combining the advantages of the green wavelength with tailored GHz burst profiles, we demonstrate that the interaction between the laser and the glass is significantly improved, resulting in faster drilling and higher-quality holes with smoother surfaces and absence of cracks. This approach lays the groundwork for advancing the understanding of GHz-burst laser processing and its transformative impact on glass drilling techniques

The demand for micrometric through-holes in glass and silicon carbide (SiC) is growing, particularly in advanced packaging and power electronics. While selective laser etching (SLE) remains the dominant method for through-glass vias (TGVs), environmental concerns and process complexity highlight the need for alternatives. One option is percussion drilling, but it faces challenges such as drilling saturation due to the conical shape of the hole, microcracks, and stress. Recently, GHz burst processing has attempted to address these issues, but some fundamental limitations remained. In this study, we showcase the unexplored potential of repetitive single-pulse femtosecond laser drilling. Using optimized focusing conditions and a femtosecond fiber laser with >200 μJ pulse energy and 250 fs duration, we achieved full penetration of up to 1 mm - thick glass and fast SiC drilling. We also demonstrate a method of multiple-hole drilling speed improvement enabled by an advanced pulse-on-demand laser feature.

Ultrafast laser ablation has been proven to allow for the generation of micromechanical devices, micro-optics and microfluidics. To successfully transfer this approach towards an industrial level, process efficiency and stability as well as resulting parts quality have to be improved. Here we report on the reproducibility and enhanced accuracy of 2.5D ultra-short pulsed laser ablation of fused silica to structure complex optics by integrating center recognition and height measurement within an automated machine setup and by sensitive adjustment of the applied laser parameters to optimize the ablated depth per path in multi-pass ablation processes. To exemplify the potential of these approaches, free-form optics and axicons are generated with improved geometrical and surface characteristics.

Laser polishing of glass using a CO2-laser beam is a contact-free alternative to mechanical polishing of optical surfaces. However, this process suffers from mid-spatial frequency errors (MSFE, 80 µm ≤ λ ≤ 2500 µm). This work presents experimental investigations into the formation of MSFE during laser polishing. Using a controlled variation of the process temperature during laser polishing of fused silica, in addition to the expected densification process, a nanoscale ablation process occurring below the evaporation temperature is observed. This ablation process first occurs at a process temperature of around 1950 °C, resulting in an ablation depth of a few nanometers, which increases to several hundred nanometers when approaching the evaporation temperature. As a result, due to fluctuations in the laser power during laser polishing, inhomogeneous ablation occurs, leading to the formation of MSFE. By utilizing a closed-loop temperature control or reducing the process temperature this issue can be mitigated.