A considerable increase in the ultrafast laser ablation rate has been reported for bursts in the GHz regime, although with controversy. We report results of the European project kW-flexiburst, obtained with a novel ultrafast laser that is highly flexible. It has an architecture that enables flexibility in terms of repetition rate (up to 15 GHz) and the number of pulses within the burst. Our recent results shine new light on different aspects of the laser processing of materials with bursts in the GHz regime, providing arguments for the actual disputation. We believe this new laser source can open new perspectives for ultrafast laser processing.
We report on mid-infrared supercontinuum generation from 4 to 9 µm in orientation-patterned gallium-arsenide waveguides pumped by nanojoule-class ultrafast fiber lasers. The QPM waveguide and the laser source are optimized in tandem to pump the waveguides close to the degeneracy by means of sub-picosecond pulses at 2760 nm. The use of a waveguide geometry drastically reduces the required energy to the nanojoule level, thereby opening supercontinuum generation in GaAs platforms to fiber lasers.
We report on the design of OP-GaAs rib waveguides for frequency conversion in the mid-infrared and explore their performances for parametric generation. The samples used are between 10 and 25 mm long and exhibit quasi-phasematched (QPM) periods from 85 to 100 μm. The waveguides are pumped by a femtosecond erbium-doped fluoride fiber laser combined with a soliton self-frequency shift converter delivering sub-300 fs pulses at a wavelength tunable between 2.8 and 3.3 μm. By adjusting the pump wavelength, our OP-GaAs platform can produce ultrashort pulses widely tunable around 4 and 12 μm for the signal and idler, respectively. These results fit quite well our calculations of QPM curves.
We report on a fiber laser setup optimized to generate and propagate high energy solitons with megawatt peak power around 1700 nm. Picosecond pulses from a chirped-pulse amplifier system at 1560 nm trigger the formation of sub-100 fs solitons with approximately 70 nJ energy in an all-solid photonic bandgap Bragg fiber with ultra-large mode area. Upon propagation in the same fiber the soliton self-frequency shift effect allows for tuning the central wavelength up to 1680 nm in a 1.5 m long piece of fiber. This work paves the way to miniaturized endomicroscopes in the biologically relevant window around 1700 nm and, thanks to the 20-cm critical bend radius of the delivery fiber, opens the way to deep in vivo imaging of freely moving animals.
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