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Université de Fribourg

Charge migration and charge transfer in molecular systems

Wörner, Hans Jakob ; Arrell, a), Christopher A. ; Banerji, Natalie ; Cannizzo, Andrea ; Chergui, Majed ; Das, Akshaya K. ; Hamm, Peter ; Keller, Ursula ; Kraus, Peter M. ; Liberatore, Elisa ; Lopez-Tarifa, Pablo ; Lucchini, Matteo ; Meuwly, Markus ; Milne, Chris ; Moser, Jacques-E. ; Rothlisberger, Ursula ; Smolentsev, Grigory ; Teuscher, Joël ; Bokhoven, Jeroen A. van ; Wenger, Oliver

In: Structural Dynamics, 2017, vol. 4, no. 6, p. 061508

The transfer of charge at the molecular level plays a fundamental role in many areas of chemistry, physics, biology and materials science. Today, more than 60 years after the seminal work of R. A. Marcus, charge transfer is still a very active field of research. An important recent impetus comes from the ability to resolve ever faster temporal events, down to the attosecond time scale. Such...

Université de Neuchâtel

Extreme ultraviolet light source at a megahertz repetition rate based on high-harmonic generation inside a mode-locked thin-disk laser oscillator

Labaye, François ; Gaponenko, Maxim ; Wittwer, Valentin J ; Diebold, A ; Paradis, Clément ; Modsching, Norbert Paul ; Merceron, Loïc ; Emaury, F ; Graumann, I.J ; Phillips, C.R ; Saraceno, C.J ; Kränkel, C ; Keller, Ursula ; Südmeyer, Thomas

In: Optics Letters, 2017, vol. 42, no. 24, p. 5170-5173

We demonstrate a compact extreme ultraviolet (XUV) source based on high-harmonic generation (HHG) driven directly inside the cavity of a mode-locked thin-disk laser oscillator. The laser is directly diode-pumped at a power of only 51 W and operates at a wavelength of 1034 nm and a 17.35 MHz repetition rate. We drive HHG in a high-pressure xenon gas jet with an intracavity peak intensity of...

Université de Neuchâtel

Carrier-envelope offset frequency stabilization of a gigahertz semiconductor disk laser

Jornod, Nayara ; Gürel, Kutan ; Wittwer, Valentin J ; Brochard, Pierre ; Hakobyan, Sargis ; Schilt, Stéphane ; Waldburger, Dominik ; Keller, Ursula ; Südmeyer, Thomas

In: Optica, 2017, vol. 4, no. 12, p. 1482-1487

Optical frequency combs based on ultrafast lasers have enabled numerous scientific breakthroughs. However, their use for commercial applications is limited by the complexity and cost of femtosecond laser technology. Ultrafast semiconductor lasers might change this issue as they can be mass produced in a cost-efficient way while providing large spectral coverage from a single technology. However,...

Université de Neuchâtel

Full stabilization and characterization of an optical frequency comb from a diode-pumped solid-state laser with GHz repetition rate

Hakobyan, Sargis ; Wittwer, Valentin J ; Brochard, Pierre ; Gürel, Kutan ; Schilt, Stéphane ; Mayer, Aline S ; Keller, Ursula ; Südmeyer, Thomas

In: Optics Express, 2017, vol. 25, no. 17, p. 20437-20453

We demonstrate the first self-referenced full stabilization of a diode-pumped solid-state laser (DPSSL) frequency comb with a GHz repetition rate. The Yb:CALGO DPSSL delivers an average output power of up to 2.1 W with a typical pulse duration of 96 fs and a center wavelength of 1055 nm. A carrier-envelope offset (CEO) beat with a signal-to-noise ratio of 40 dB (in 10-kHz resolution bandwidth) is...

Université de Neuchâtel

High-power amplification of a femtosecond vertical external-cavity surface-emitting laser in an Yb : YAG waveguide

Jornod, Nayara ; Wittwer, Valentin J ; Kränkel, Christian ; Waldburger, Dominik ; Keller, Ursula ; Südmeyer, Thomas ; Calmano, Thomas

In: Optics Express, 2017, vol. 25, no. 14, p. 16527-16533

We present the amplification of a mode-locked vertical external-cavity surfaceemitting laser (VECSEL) using an Yb:YAG crystalline waveguide as gain medium. The VECSEL seed laser operates at a center wavelength of 1030 nm and generates 300-fs pulses at a repetition rate of 1.77 GHz. An average seed power of 60 mW was launched onto a 8.3 mm long fs-laser written Yb:YAG waveguide pumped by 7.7 W...

Université de Neuchâtel

First investigation of the noise and modulation properties of the carrier-envelope offset in a modelocked semiconductor laser

Brochard, Pierre ; Jornod, Nayara ; Schilt, Stéphane ; Wittwer, Valentin J ; Hakobyan, Sargis ; Waldburger, Dominik ; Link, Sandro M ; Alfieri, Cesare G. E ; Golling, Matthias ; Devenoges, Laurent ; Morel, Jacques ; Keller, Ursula ; Südmeyer, Thomas. Laboratoire Temps-Fréquence, Université de Neuchâtel, Switzerland

In: Optics Letters, 2016, vol. 41, no. 14, p. 3165-3168

We present the first characterization of the noise properties and modulation response of the carrier-envelope offset (CEO) frequency in a semiconductor modelocked laser. The CEO beat of an optically-pumped vertical external-cavity surface-emitting laser (VECSEL) at 1030 nm was characterized without standard ƒ-to-2ƒ interferometry. Instead, we used an appropriate combination of...