Options
Südmeyer, Thomas
Nom
Südmeyer, Thomas
Affiliation principale
Fonction
Directeur
Email
thomas.sudmeyer@unine.ch
Identifiants
Résultat de la recherche
Voici les éléments 1 - 10 sur 33
- PublicationAccès libreCarrier-envelope offset frequency stabilization of a thin-disk laser oscillator operating in the strongly self-phase modulation broadened regime
; ; ; ; ; - PublicationAccès libreBroadband terahertz pulse generation driven by an ultrafast thin-disk laser oscillator
; ; - PublicationAccès libreCarrier-envelope offset stabilization of a GHz repetition rate femtosecond laser using opto-optical modulation of a SESAM
; ; We demonstrate, to the best of our knowledge, the first carrier-envelope offset (CEO) frequency stabilization of a GHz femtosecond laser based on opto-optical modulation (OOM) of a semiconductor saturable absorber mirror (SESAM). The 1.05-GHz laser is based on a Yb:CALGO gain crystal and emits sub-100-fs pulses with 2.1-W average power at a center wavelength of 1055 nm. The SESAM plays two key roles: it starts and stabilizes the mode-locking operation and is simultaneously used as an actuator to control the CEO frequency. This second functionality is implemented by pumping the SESAM with a continuous-wave 980-nm laser diode in order to slightly modify its nonlinear reflectivity. We use the standard ƒ-to-2ƒ method for detection of the CEO frequency, which is stabilized by applying a feedback signal to the current of the SESAM pump diode. We compare the SESAM-OOM stabilization with the traditional method of gain modulation via control of the pump power of the Yb:CALGO gain crystal. While the bandwidth for gain modulation is intrinsically limited to ∼250 kHz by the laser cavity dynamics, we show that the OOM provides a feedback bandwidth above 500 kHz. Hence, we were able to obtain a residual integrated phase noise of 430 mrad for the stabilized CEO beat, which represents an improvement of more than 30% compared to gain modulation stabilization. - PublicationMétadonnées seulementHigh-power integrated ultrafast semiconductor disk laser: multi-Watt 10 GHz pulse generation(2012)
; ; Keller, Ursula - PublicationAccès libreCarrier-Envelope Offset Frequency Stabilization of a Thin-Disk Laser Oscillator via Depletion Modulation
; ; ; Morgner, UweWe present a novel concept for the stabilization of the carrier-envelope offset (CEO) frequency of femtosecond pulse trains from thin-disk laser oscillators by exploiting gain depletion modulation in the active gain region. We shine a small fraction of the laser output power back onto the thin disk allowing the population inversion in the gain medium to be controlled. We employ this technique in our home-built Kerr-lens mode-locked Yb:YAG thin-disk laser and benchmark the performance against the proven technique of pump current modulation for CEO stabilization, showing that the two techniques have equivalent performance. The new method which only requires an additional AOM demonstrates a scalable and cost-effective method for CEO stabilization of high-power laser oscillators. - PublicationMétadonnées seulementHigh-power MIXSEL: an integrated ultrafast semiconductor laser with 6.4 W average power(2010)
; ; Keller, Ursula - 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. - PublicationMétadonnées seulementFemtosecond VECSEL with tunable multi-gigahertz repetition rate(2011)
; ; Keller, Ursula - PublicationAccès libreFrequency comb metrology with an optical parametric oscillator
; ; ; - 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.