Abstract

Ultrafast fiber laser systems with sub-200fs pulse duration and pulse energies in the μJ-range operating at a wavelength around 1μm are excellent tools for a variety of applications in efficient and high-quality micromachining processes, e.g. structuring, cutting or drilling of different materials and surfaces, respectively. To achieve high pulse energies, the output of a low-power seed oscillator is commonly boosted in subsequently arranged amplifiers by using chirped pulse amplification (CPA) schemes in order to avoid distinct nonlinear effects in the fiber sections. However, in either case the reduction of the emission bandwidth during amplification, resulting from the limited gain bandwidth and leading to a substantial increase of pulse duration, must be addressed for the generation of that short femtosecond pulses. In order to overcome this gain narrowing effect, several methods have been developed, including the use of matched spectral filters [1], parabolic pulse evolution [2], etc.

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