G. Martel

Dissipative solitons in a passively mode-locked Er-doped fiber with strong normal dispersion.

We report on ultrashort pulse generation from a passively mode-locked erbium fiber laser operating in the highly positive dispersion regime. Highly-chirped pulses with 5.3 ps duration and spectral bandwidth of 8.3 nm are generated. They are extra-cavity compressed down to 757 fs. Numerical simulations confirm the experimental results and show that these pulses could be interpreted as dissipative solitons.

Evidence of Brillouin scattering in an ytterbium-doped double-clad fiber laser.

We have designed and performed an experiment that permitted direct observation of Brillouin backscattering in an Yb-doped double-clad fiber laser. Fifteen Brillouin-shifted frequencies were observed for the first time to our knowledge. We clearly demonstrate that stimulated Brillouin scattering is directly responsible for both fast transient dynamics of the laser and reduction of the lasers pulse width.

Influence of cavity losses on stimulated Brillouin scattering in a self-pulsing side-pumped ytterbium-doped double-clad fiber laser

We investigate experimentally the influence of cavity losses on Brillouin backscattering in an Yb-doped double-clad fiber laser. We show that stimulated Brillouin scattering is enhanced around a particular value of the cavity losses.

On the possibility of observing bound soliton pairs in a wave-breaking-free mode-locked fiber laser

On the basis of numerical simulations, we explain the formation of the stable bound soliton pairs that were experimentally reported in a high-power mode-locked ytterbium fiber laser [Opt. Express 14, 6075 (2006)], in a regime where wave-breaking-free operation is expected. A fully vectorial model allows one to rigorously reproduce the nonmonotonic nature for the nonlinear polarization effect that generally limits the power scalability of a single-pulse self-similar regime. Simulations show that a self-similar regime is not fully obtained, although positive linear chirps and parabolic spectra are always reported. As a consequence, nonvanishing pulse tails allow distant stable binding of highly-chirped pulses.

Numerical Maps for Fiber Lasers Mode Locked with Nonlinear Polarization Evolution: Comparison with Semi-Analytical Models

Abstract We have used a fully vectorial model based on two coupled nonlinear Schrödinger equations to study mode locking and pulse generation initiated and stabilized by nonlinear polarization evolution in a stretched pulse, double-clad, Yb-doped, fiber laser. The model takes explicitly into account gain saturation, finite amplification bandwidth, Kerr-induced self- and cross-phase modulations, group velocity dispersion, polarization control, and linear birefringence. Complete maps versus the orientation of intra-cavity wave-plates have been established. They comprise a large variety of pulse regimes that can be simply obtained by turning the intracavity wave-plate: stable single pulse per round trip, multiple pulsing, unstable pulsing on a continuous wave (CW) background, as well as limit cycles. In addition, we have demonstrated that linear birefringence plays a key role in the pulse-shaping mechanism induced by nonlinear polarization evolution.

Non-Gaussian fundamental laser mode oscillation in end-pumped Nd:YVO4 microchip laser

Abstract Far-Field non-Gaussian fundamental transverse modes have been obtained in CW end-pumped Nd:YVO 4 microchip laser for particular cavity lengths. Such profiles appear at threshold and are not distorted when pump power increases but they strongly depend on the pump to mode size ratio. An implemented theoretical model qualitatively reproduces these transverse profiles. It is based on the hypothesis of diffraction effects of the resonant intra-cavity field on a Gaussian-gain profile. Dependence of the pump to mode size ratio on such profiles will be also theoretically explained.

Experimental and theoretical evidence of pump-saturation effects in low power end-pumped Nd:YVO4 microchip laser

Abstract Pump-saturation effects have been measured in a miniaturized end-pumped solid-state Nd:YVO 4 laser. In particular we have investigated the influence of the pump beam width on the laser characteristics (threshold pump power and laser efficiency). A numerical rate-equation model has been developed in order to explain these results and lead to a good quantitative agreement with the experimental data.

Coupling atom probe tomography and photoluminescence spectroscopy: Exploratory results and perspectives

The development of laser-assisted atom probes makes it possible, in principle, to exploit the femtosecond laser pulse not only for triggering ion evaporation from a nanometric field emission tip, but also for generating photons via the radiative recombination of electron-hole pairs in tips made of dielectric materials. In this article we demonstrate a first step towards a correlation of micro-photoluminescence (μ-PL) and laser-assisted tomographic atom probe (LA-TAP) analysis applied separately on the same objects, namely on ZnO microwires. In particular, we assess that the use of the focused ion beam (FIB) tip preparation method significantly degrades the radiative recombination yield of the analyzed microwires. We discuss the strategies to avoid the FIB-induced damage on the optical properties of the sample and how to get beyond the correlated μ-PL and LA-TAP analysis with a coupled approach allowing to perform the two analyses within the same instrument.

Beam propagation factor of truncated laguerre—gauss beams

Abstract Beam propagation factor (usually referred to as M 2 factor) and brightness of high-order symmetrical Laguerre–Gauss (LG) beams that diffract upon a hard-aperture are investigated. We demonstrate that a circular aperture is able to decrease the M 2 factor of a high-order symmetrical LG beam and also to enhance its brightness although losses are induced.

Dynamics of a vectorial neodymium-doped fibre laser passively Q switched by a polymer-based saturable absorber

Abstract We report the dynamic regimes obtained in a bipolarized neodymium-doped fibre laser self Q switched by a thin slice of a polymerbased saturable absorber. We demonstrate the influence of the total losses and of the anisotropic losses induced by defocusing the saturable absorber and by tilting the cavity mirror, respectively. Starting from a global chaotic behaviour for low-loss configuration, the system evolves toward an n-periodic (n = 4, 2 and 1) regime for increasing losses. Stabilization of these regimes depends on the anisotropic losses. Conversely, when cavity mirrors are tilted alone, an additional regime such as intermittence is obtained. All these regimes have been identified as due to nonlinear coupling through the saturable absorber between two distinct polarized modes. These modes have been experimentally resolved.