Double- and multi-femtosecond pulses produced by birefringent crystals for the generation of 2D laser-induced structures on a stainless steel surface

Laser-induced textures have been proven to be excellent solutions for modifying wetting, friction, biocompatibility, and optical properties of solids. The possibility to generate 2D-submicron morphologies by laser processing has been demonstrated recently. Employing double-pulse irradiation, it is possible to control the induced structures and to fabricate novel and more complex 2D-textures. Nevertheless, double-pulse irradiation often implies the use of sophisticated setups for modifying the pulse polarization and temporal profile. Here, we show the generation of homogeneous 2D-LIPSS (laser-induced periodic surface structures) over large areas utilizing a simple array of birefringent crystals. Linearly and circularly polarized pulses were applied, and the optimum process window was defined for both. The results are compared to previous studies, which include a delay line, and the reproducibility between the two techniques is validated. As a result of a systematic study of the process parameters, the obtained morphology was found to depend both on the interplay between fluence and inter-pulse delay, as well as on the number of incident pulses. The obtained structures were characterized via SEM (scanning electron microscopy) and atomic force microscopy. We believe that our results represent a novel approach to surface structuring, primed for introduction in an industrial environment

THz-Time Domain Spectroscopy system for applications to radical detection

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THz-Time Domain Spectroscopy system for applications to radical detection

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THz-Time Domain Spectroscopy system for applications to radical detection

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Femtosecond laser processing of silver-containing glass with optical vortex beams

We report on vortex-assisted femtosecond direct laser writing (DLW) in silver-containing phosphate glasses with complex light fields endowed with optical phase singularities. This allows us to engrave complex patterns showing sub-wavelength dimensions. The associated linear and nonlinear optical properties show remarkably correlated but distinct spatial distributions. The creation of a perennial buried electric field leads to an efficient electric- field induced second harmonic generation. The magnitude and distribution of such buried field is also considered to actively drive the pattern topology of the fluorescent silver clusters. Using DLW with phase and amplitude engineered beams, we demonstrate a promising approach to control both fluorescent and nonlinear responses below the diffraction limit

Lasing properties of new Yb-doped borate compounds with varying gadolinium and yttrium concentration

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3D millimeter waves Tomosynthesis for the control of aeronautics materials

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High-power picosecond pulses by SPM-induced spectral compression in a fiber amplifier

The fiber based generation of nearly transform-limited 10-ps pulses with 200 kW peak power (97 W average power) based on SPM-induced spectral compression is reported. Efficient second harmonic generation applying this source is also discussed

3D Terahertz Imaging for the Control of Aeronautics Composite Multilayered Structures

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3D Terahertz Imaging for the Control of Aeronautics Composite Multilayered Structures

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