Spatially Structured Optical Pump for Laser Generation Tuning.

The goal and essential parameter of laser light conversion is achieving emitted radiation of higher brightness. For many applications, the laser beam must have the highest available beam quality and highest achievable power. However, lasers with higher average power values usually have poorer beam quality, limiting the achievable brightness. Here, we present a method for improving the beam quality by using a spatially structured optical pump for a membrane external cavity laser resonator. An increase in brightness is achieved under fixed focusing conditions just by changing the pump intensity profile. A controllable output laser mode can be achieved by using a dynamically changing pump pattern.

On-Demand Wettability via Combining fs Laser Surface Structuring and Thermal Post-Treatment.

Laser surface texturing (LST) is one of the surface modification methods that increase or provide new abilities for the material surface. Textured surfaces could be applied in different industrial areas to reduce wear and friction, promote anti-fouling, improve osseointegration, and other similar uses. However, LST is still in development and for reaching industrial level further optimization is required. In this paper, different metal alloy surfaces were fabricated with several patterns using the same laser parameters on each material and the results were compared. This could lead to possible optimization on the industrial level. Furthermore, research on the wettability properties of material and texture patterns depending on heat treatment in different temperatures was performed, showing complete control for wettability (from hydrophilic to hydrophobic).

Dynamic aberration correction via spatial light modulator (SLM) for femtosecond direct laser writing: towards spherical voxels.

Optical aberrations are a type of optical defect of imaging systems that hinder femtosecond direct laser write machining by changing voxel size and aspect ratio in different sample depths. We present an approach of compensating such aberrations using a liquid crystal spatial light modulator (SLM). Two methods for correcting are explored. They are based on backward ray tracing and Zernike polynomials. Experiments with a long focal distance lens (F = 25 and 50 mm) and microscope objective (100x, 0.9 NA) have been conducted. Specifically, aberration-free structuring with voxels of a constant aspect ratio of 1-1.5 is carried out throughout a 1 mm thick sample. Results show potential in simplifying direct laser writing and enabling new architectures made possible by near-spherical voxels.