Temporal cleaning of a high energy fiber-based ultrafast laser using cross-polarized wave generation

International audienceWe report the use of cross-polarized wave generation to perform both pulse shortening and temporal cleaning of a high-energy ytterbium-doped fiber-based femtosecond laser system. The nonlinear processes allow both a highly efficient nonlinear conversion of 20% and a large compression ratio of 3.5, with inherently improved coherent and incoherent contrasts. This results in the generation of 37 μJ, 115 fs pulses at a repetition rate of 100 kHz with high temporal quality

Nonlinear compression of high energy fiber amplifier pulses in air-filled hypocycloid-core Kagome fiber

International audienceWe report on the generation of 34 fs and 50 µJ pulses from a high energy fiber amplifier system with nonlinear compression in an air-filled hypocycloid-core Kagome fiber. The unique properties of such fibers allow bridging the gap between solid core fibers-based and hollow capillary-based post-compression setups, thereby operating with pulse energies obtained with current state-of-the-art fiber systems. The overall transmission of the compression setup is over 70%. Together with Yb-doped fiber amplifier technologies, Kagome fibers therefore appear as a promising tool for efficient generation of pulses with durations below 50 fs, energies ranging from 10 to several hundreds of µJ, and high average powers

Crack-free high-aspect ratio holes in glasses by top–down percussion drilling with infrared femtosecond laser GHz-bursts

We report novel results on top-down percussion drilling in different glasses with femtosecond laser GHz-bursts. Thanks to this particular regime of light – matter interaction, combining non-linear absorption and thermal cumulative effects, we obtained crack-free holes of aspect ratios exceeding 30 in sodalime and 70 in fused silica. The results are discussed in terms of inner wall morphology, aspect ratio and drilling speed

Comparative Study of Percussion Drilling in Glasses with a Femtosecond Laser in Single Pulse, MHz-Burst, and GHz-Burst Regimes and Optimization of the Hole Aspect Ratio

In this contribution, we present a comparative study on top-down drilling in sodalime glass, with a femtosecond laser operating in single-pulse, MHz-burst and GHz-burst modes, respectively. We investigate the hole depth, drilling rate, and hole morphology for these three regimes while keeping the same experimental conditions. We demonstrate that, for both burst regimes, the burst length has to be adapted for optimizing the hole depth. In the GHz-burst regime, the lower the ablation rate the longer the holes. The three drilling regimes lead to different hole morphologies, where the GHz-burst mode results in the best hole quality featuring glossy inner walls and an almost cylindrical morphology. Furthermore, we obtain crack-free holes, the deepest measuring 3.7 mm in length and 25 µm in entrance diameter corresponding to an aspect ratio of 150, which is the highest aspect ratio reported thus far with femtosecond GHz-burst drilling to the best of our knowledge

Bessel Beam Dielectrics Cutting with Femtosecond Laser in GHz-Burst Mode

We report, for the first time to the best of our knowledge, Bessel beam dielectrics cutting with a femtosecond laser in GHz-burst mode. The non-diffractive beam shaping is based on the use of an axicon and allows for cutting glasses up to 1 mm thickness with an excellent cutting quality. Moreover, we present a comparison of the cutting results with the state-of-the-art method, consisting of short MHz-bursts of femtosecond pulses. We further illustrate the influence of the laser beam parameters such as the burst energy and the pitch between consecutive Bessel beams on the machining quality of the cutting plane and provide process windows for both regimes

Generation of 150-fs pulses from a diode-pumped Yb:KYW nonlinear regenerative amplifier

International audienceGeneration of sub-150-fs-level pulses has been obtained from an Yb-doped crystal-based regenerative amplifier by applying an innovative amplification scheme. This scheme is based on optimization of the linear and non-linear phase during the amplification process inside the regenerative amplifier cavity. This technique with Yb:KYW allows to achieve pulse durations from diode-pumped Yb-doped regenerative amplifiers that were up to now only accessible with more complex Ti:sapphire amplifiers. With this Yb-doped tungstate crystal used in regenerative amplifiers, 145 fs pulses centered at 1026 nm with a spectral bandwidth of 14 nm at 50 kHz for an average power of 1.6 W have been generated

Optics-free kagome fiber-aided laser micro-machining

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Milli-Joule energy-level comb and supercontinuum generation in atmospheric air-filled inhibited coupling Kagome fiber

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