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Farewell: the NCCR MUST ended 
MUST2022 Conference
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Unusual keynote talk at an international scientific conference
NCCR MUST at Scientifica 2021Multi-stage ytterbium fiber-amplifier for weak picosecond laser pulses generated by a gain-switched laser-diode
| Date | Do, 26.04.2012 | |
| Time | 10.15 | |
| Speaker | Dr. Manuel Ryser, Institute of Applied Physics, University of Bern | |
| Location | Universität Bern, Institut für Angewandte Physik, Gebäude exakte Wissenschaften, Hörsaal B116, Sidlerstrasse 5, 3012 Bern | |
| Program | In the frame of a CTI project we have developed a five stage fiber-amplifier that is seeded by a gain-switched laser diode. The system delivers laser pulses of 11 picosecond pulse width (FWHM), with a peak power of >0.6MW and at a repetition rate of 1MHz. In this project was followed an interesting approach for the generation of energetic picosecond pulses: a gain-switched laser diode was combined with a multi-stage fiber amplifier. Gain-switching of laser diodes allows electronic triggering of the laser pulses that can be a very attractive feature for manifold applications such as for example material processing or nonlinear wave-mixing. Drawback of gain-switched laser diodes is the weak output pulse energy in the order of few 100fJ. However, fiber amplifiers allow the low-noise amplification of weak signals and are thus ideally suited to amplify the weak pulse trains from the gain-switched laser diodes. Our fiber-amplifier amplifies the input signal from the gain-switched laser-diode by 72dB. The core diameters of the fibers were increased for the successive stages from 4μm at the first stage to 70μm at the final amplification stage in order to minimize undesired non-linear effects or prevent from damage of the fibers due to the high peak powers. For the final amplification-stages was used a recently developed special fiber that only guides few modes, i.e. exhibits good beam quality, in spite of its large fiber core diameter of 70μm. In this talk details of the developed fiber laser system will be discussed. The low-noise Ytterbium fiber based amplification of the weak laser pulses generated by the gain-switched laser diode will be presented. Furthermore the fundamental physical limitations for ultra-short pulse amplification when reaching peak powers i.e. nonlinearities and fiber damage thresholds and ways to push these limits will be shown. | |
| Link | www.iap.unibe.ch | |
