Bessel beams, known for maintaining focus over long distances, find many applications in imaging, nonlinear optics and laser material processing. For these applications, generating sub-micrometer Bessel beams is essential, but requires complex optical systems. Traditional optical software, designed for ray tracing, are challenged for this task. Here we show how we can use optical software to create and optimize optical design to generate these unconventional beams. The research involves high numerical aperture systems, investigates the influence of polarization, and the use of diffractive optical elements. Numerical findings are compared to experimental results, highlighting the potential of software-assisted beam design for various applications.
Ultrafast pump-probe imaging requires both an accurate synchronization of probe pulses with the pump and that the probe pulses are free from spatio-temporal distortions. However, characterizing weak probes inside transparent solids reveals to be particularly difficult. We report a new in-situ diagnostic for ultrashort probes using a micrometric-sized Kerr-based transient grating induced in the sample by a shaped pump pulse. Our configuration allows us to synchronize pump and probe pulses in-situ, to measure the ultrashort probe pulse duration, and to remove pulse front tilt of the weak probe. Our approach is valid for any probe wavelength and polarization.
Shaping complex light fields such as nondiffracting beams, provide important novel routes to control laser materials processing. Nondiffracting beams are produced from an interference between waves with an angle kept constant along the propagation direction. These beams are of outmost importance for laser materials processing because they offer invariant light-matter interaction conditions. We have used and developed several families of beams generated with phase and amplitude shaping and we will review their impact for laser surface processing and high aspect ratio laser processing in the bulk of transparent materials. Bessel beams and higher order Bessel beams allow for high aspect ratio channel drilling, elongated void creation in the bulk of transparent media, or tubular damage creation. We will also discuss the impact of accelerating beam shaping, ie beams with a curved main intensity lobe, to dice materials with a curved edge.
This project has received funding from the European Research Council (ERC) under the European
Union's Horizon 2020 research and innovation programme (grant agreement No 682032-PULSAR).
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