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Südmeyer, Thomas
Nom
Südmeyer, Thomas
Affiliation principale
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Directeur
Email
thomas.sudmeyer@unine.ch
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Voici les éléments 1 - 7 sur 7
- PublicationAccès libreUltrafast thin-disk laser with 80 µJ pulse energy and 242 W of average power
; ; Keller, UrsulaWe present a semiconductor saturable absorber mirror (SESAM) mode-locked thin-disk laser generating 80 µJ of pulse energy without additional amplification. This laser oscillator operates at a repetition rate of 3.03 MHz and delivers up to 242 W of average output power with a pulse duration of 1.07 ps, resulting in an output peak power of 66 MW. In order to minimize the parasitic nonlinearity of the air inside the laser cavity, the oscillator was operated in a vacuum environment. To start and stabilize soliton mode locking, we used an optimized high-damage threshold, low-loss SESAM. With this new milestone result, we have successfully scaled the pulse energy of ultrafast laser oscillators to a new performance regime and can predict that pulse energies of several hundreds of microjoules will become possible in the near future. Such lasers are interesting for both industrial and scientific applications, for example for precise micromachining and attosecond science. - PublicationAccès libreCutting-Edge High-Power Ultrafast Thin Disk Oscillators
; ; Keller, UrsulaA growing number of applications in science and industry are currently pushing the development of ultrafast laser technologies that enable high average powers. SESAM modelocked thin disk lasers (TDLs) currently achieve higher pulse energies and average powers than any other ultrafast oscillator technology, making them excellent candidates in this goal. Recently, 275 W of average power with a pulse duration of 583 fs were demonstrated, which represents the highest average power so far demonstrated from an ultrafast oscillator. In terms of pulse energy, TDLs reach more than 40 µJ pulses directly from the oscillator. In addition, another major milestone was recently achieved, with the demonstration of a TDL with nearly bandwidth-limited 96-fs long pulses. The progress achieved in terms of pulse duration of such sources enabled the first measurement of the carrier-envelope offset frequency of a modelocked TDL, which is the first key step towards full stabilization of such a source. We will present the key elements that enabled these latest results, as well as an outlook towards the next scaling steps in average power, pulse energy and pulse duration of such sources. These cutting-edge sources will enable exciting new applications, and open the door to further extending the current performance milestones. - PublicationAccès libre275 W average output power from a femtosecond thin disk oscillator operated in a vacuum environment
; ; Keller, UrsulaWe present an ultrafast thin disk laser that generates an average output power of 275 W, which is higher than any other modelocked laser oscillator. It is based on the gain material Yb:YAG and operates at a pulse duration of 583 fs and a repetition rate of 16.3 MHz resulting in a pulse energy of 16.9 µJ and a peak power of 25.6 MW. A SESAM designed for high damage threshold initiated and stabilized soliton modelocking. We reduced the nonlinearity of the atmosphere inside the cavity by several orders of magnitude by operating the oscillator in a vacuum environment. Thus soliton modelocking was achieved at moderate amounts of self-phase modulation and negative group delay dispersion. Our approach opens a new avenue for power scaling femtosecond oscillators to the kW level. - PublicationAccès libreHigh-power integrated ultrafast semiconductor disk laser: multi-Watt 10 GHz pulse generation
; ; ; Keller, UrsulaPresented is an optically pumped modelocked integrated externalcavity surface emitting laser (MIXSEL) with a pulse repetition rate of 10 GHz, generating picosecond pulses at 2.4 W average output power at a centre wavelength of 963 nm. The MIXSEL structure integrates both the absorber and the gain layers within the same wafer. The saturable absorber is a single layer of self-assembled InAs quantum dots (QD) and the gain is obtained with seven InGaAs quantum wells. It is shown that the picosecond pulse duration is limited by the slow recovery time of the integrated QD saturable absorber. - PublicationAccès libreExperimentally verified pulse formation model for high-power femtosecond VECSELs
; ; ; Keller, UrsulaOptically pumped vertical-external-cavity surface-emitting lasers (OP-VECSELs), passively modelocked with a semiconductor saturable absorber mirror (SESAM), have generated the highest average output power from any sub-picosecond semiconductor laser. Many applications, including frequency comb synthesis and coherent supercontinuum generation, require pulses in the sub-300-fs regime. A quantitative understanding of the pulse formation mechanism is required in order to reach this regime while maintaining stable, high-average-power performance. We present a numerical model with which we have obtained excellent quantitative agreement with two recent experiments in the femtosecond regime, and we have been able to correctly predict both the observed pulse duration and the output power for the first time. Our numerical model not only confirms the soliton-like pulse formation in the femtosecond regime, but also allows us to develop several clear guidelines to scale the performance toward shorter pulses and higher average output power. In particular, we show that a key VECSEL design parameter is a high gain saturation fluence. By optimizing this parameter, 200-fs pulses with an average output power of more than 1 W should be possible. - PublicationAccès libreLow repetition rate SESAM modelocked VECSEL using an extendable active multipass-cavity approach
; ; ; Keller, UrsulaUltrafast VECSELs are compact pulsed laser sources with more flexibility in the emission wavelength compared to diode-pumped solid-state lasers. Typically, the reduction of the pulse repetition rate is a straightforward method to increase both pulse energy and peak power. However, the relatively short carrier lifetime of semiconductor gain materials of a few nanoseconds sets a lower limit to the repetition rate of passively modelocked VECSELs. This fast gain recovery combined with low pulse repetition rates leads to the buildup of multiple pulses in the cavity. Therefore, we applied an active multipass approach with which demonstrate fundamental modelocking at a repetition rate of 253 MHz with 400 mW average output power in 11.3 ps pulses. - PublicationAccès libreVECSEL gain characterization
; ; ; Keller, UrsulaWe present the first full gain characterization of two vertical external cavity surface emitting laser (VECSEL) gain chips with similar designs operating in the 960-nm wavelength regime. We optically pump the structures with continuous-wave (cw) 808-nm radiation and measure the nonlinear reflectivity for 130-fs and 1.4-ps probe pulses as function of probe pulse fluence, pump power, and heat sink temperature. With this technique we are able to measure the saturation behavior for VECSEL gain chips for the first time. The characterization with 1.4-ps pulses resulted in saturation fluences of 40-80 µJ/cm2, while probing with 130-fs pulses yields reduced saturation fluences of 30-50 µJ/cm2 for both structures. For both pulse durations this is lower than previously assumed. A small-signal gain of up to 5% is obtained with this technique. Furthermore, in a second measurement setup, we characterize the spectral dependence of the gain using a tunable cw probe beam. We measure a gain bandwidth of over 26 nm for both structures, full width at half maximum.