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Université de Neuchâtel

Carrier-envelope offset frequency stabilization of a thin-disk laser oscillator operating in the strongly self-phase modulation broadened regime

Modsching, Norbert ; Paradis, Clément ; Brochard, Pierre ; Jornod, Nayara ; Gürel, Kutan ; Kränkel, Christian ; Schilt, Stéphane ; Wittwer, Valentin J ; Südmeyer, Thomas

In: Optics Express, 2018, vol. 26, no. 22, p. 28461-28468

We demonstrate the carrier-envelope offset (CEO) frequency stabilization of a Kerr lens mode-locked Yb:Lu2O3 thin-disk laser oscillator operating in the strongly self-phase modulation (SPM) broadened regime. This novel approach allows overcoming the intrinsic gain bandwidth limit and is suited to support frequency combs from sub-100-fs pulse trains with very high output...

Université de Neuchâtel

Broadband terahertz pulse generation driven by an ultrafast thin-disk laser oscillator

Clément, Paradis ; Drs, Jakub ; Modsching, Norbert ; Razskazovskaya, Olga ; Meyer, Frank ; Kränkel, Christian ; Saraceno, Clara J ; Wittwer, Valentin J ; Südmeyer, Thomas

In: Optics Express, 2018, vol. 26, no. 20, p. 26377-26384

We demonstrate broadband THz generation driven by an ultrafast thin-disk laser (TDL) oscillator. By optical rectification of 50-fs pulses at 61 MHz repetition rate in a collinear geometry in crystalline GaP, THz radiation with a central frequency at around 3.4 THz and a spectrum extending from below 1 THz to nearly 7 THz are generated. We realized a spectroscopic characterization of a GaP crystal...

Accès public à partir du 1 févr. 2019
Université de Neuchâtel

Kerr lens mode-locked Yb:CALGO thin-disk laser

Modsching, Norbert ; Paradis, Clément ; Labaye, François ; Gaponenko, Maxim ; Graumann, Ivan J ; Diebold, Andreas ; Emaury, Florian ; Wittwer, Valentin J ; Südmeyer, Thomas

In: Optics Letters, 2018, vol. 43, no. 4, p. 879-882

We demonstrate the first Kerr lens mode-locked Yb:CaGdAlO4 (Yb:CALGO) thin-disk laser oscillator. It generates pulses with a duration of 30 fs at a central wavelength of 1048 nm and a repetition rate of 124 MHz. The laser emits the shortest pulses generated by a thin-disk laser oscillator, equal to the shortest pulse duration obtained by Yb-doped bulk oscillators. The average output...

Université de Neuchâtel

Ramsey spectroscopy in a Rubidium vapor cell and realization of an ultra-stable atomic clock

Gharavipour, Mohammadreza ; Mileti, Gaetano (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2018.

Divers domaines d’application dans l’industrie, les télécommunications, la navigation et l’espace exigent des étalons de fréquence fiables, compacts et performants avec un niveau de stabilité de −14 à 105s (équivalent à <1 ns/jour). Avec la technologie des lasers à semi-conducteurs, la technique du pompage optique par laser a ouvert de nouveaux...

Accès public à partir du 1 août 2019
Université de Neuchâtel

Ultra-low noise microwave generation with a free-running optical frequency comb transfer oscillator

Brochard, Pierre ; Schilt, Stéphane ; Südmeyer, Thomas

In: Optics Letters, 2018, vol. 43, no. 19, p. 4651-4654

We present ultra-low noise microwave synthesis by optical to radio-frequency (RF) division realized with a free-running or RF-locked optical frequency comb (OFC) acting as a transfer oscillator. The method does not require any optical lock of the OFC and circumvents the need for a high-bandwidth actuator. Instead, the OFC phase noise is electrically removed from a beat-note signal with an optical...

Université de Fribourg

Truncating the memory time in nonequilibrium dynamical mean field theory calculations

Schüler, Michael ; Eckstein, Martin ; Werner, Philipp

In: Physical Review B, 2018, vol. 97, no. 24, p. 245129

The nonequilibrium Green's functions (NEGF) approach is a versatile theoretical tool, which allows to describe the electronic structure, spectroscopy, and dynamics of strongly correlated systems. The applicability of this method is, however, limited by its considerable computational cost. Due to the treatment of the full two-time dependence of the NEGF, the underlying equations of motion...

Université de Fribourg

Randomizing growing networks with a time-respecting null model

Ren, Zhuo-Ming ; Mariani, Manuel Sebastian ; Zhang, Yi-Cheng ; Medo, Matú?

In: Physical Review E, 2018, vol. 97, no. 5, p. 052311

Complex networks are often used to represent systems that are not static but grow with time: People make new friendships, new papers are published and refer to the existing ones, and so forth. To assess the statistical significance of measurements made on such networks, we propose a randomization methodology—a time- respecting null model—that preserves both the network's degree sequence...

Université de Fribourg

Revealing in-block nestedness: Detection and benchmarking

Solé-Ribalta, Albert ; Tessone, Claudio J. ; Mariani, Manuel S. ; Borge-Holthoefer, Javier

In: Physical Review E, 2018, vol. 97, no. 6, p. 062302

As new instances of nested organization—beyond ecological networks—are discovered, scholars are debating the coexistence of two apparently incompatible macroscale architectures: nestedness and modularity. The discussion is far from being solved, mainly for two reasons. First, nestedness and modularity appear to emerge from two contradictory dynamics, cooperation and competition. Second, ...