Passive harmonic mode-locking in a fiber laser with nonlinear polarization rotation

On basis of numerical simulation and analytical treatment, we investigate the multiple pulse passive mode-locking of a fiber laser with nonlinear loss due to the nonlinear polarization rotation technique. Various additional mechanisms resulting in the ordering of ultrashort pulses inside the laser resonator and in the realization of harmonic passive mode-locking are analyzed. Among which are the active harmonic modulation of the intracavity loss or of the refractive index, the passive modulation of the index due to the inertial properties of intracavity elements, and the amplification modulation due to the depletion and the relaxation of the gain. The velocity of pulses relative to each other is determined, it results in attractive or repulsive pulse–pulse interaction, and allows to evaluate the conditions of ordering of the pulses inside the cavity

Comments on Supergravity Description of S-branes

This is a note on the coupled supergravity-tachyon matter system, which has been earlier proposed as a candidate for the effective space-time description of S-branes. In particular, we study an ansatz with the maximal ISO(p+1)xSO(8-p,1) symmetry, for general brane dimensionality p and homogeneous brane distribution in transverse space \rho_\perp. A simple application of singularity theorems shows that (for p \le 7) the most general solution with these symmetries is always singular. (This invalidates a recent claim in the literature.) We include a few general comments about the possibility of describing the decay of unstable D-branes in purely gravitational terms.Comment: 19 pages, refs adde

Spectral-selective management of dissipative solitons in passive mode-locked fibre lasers

We study properties of dissipative solitons in passive mode-locked fibre lasers due to additional intracavity narrow spectral selection. Such selection allows us to control the soliton velocity, the nature of the interaction between solitons (attraction or repulsion), to create a bistable state in which the velocity of a single soliton can have two different values, to realize an elastic particle-like collision between single solitons. In the investigated laser system, the soliton interaction distance can be considerably larger than the soliton duration, which allows the realization of passive harmonic mode-locking

Laser à fibre verrouillé en phase à haute cadence

We investigate different ways to considerably increase the repetition-rate of passively mode-locked fiber lasers. We first report the harmonic mode-locking of a double-clad fiber laser passively mode-locked through nonlinear polarization rotation. We then consider the theoretical possibility to generate a bound-state filling the optical cavity thus resulting in ultra-high repetition rate with a remarkable stability

Brillouin instabilities in continuously pumped high power fiber lasers

The effect of Brillouin backscattering on the stability of a high power continuously pumped fiber laser is theoretically analyzed in the general framework of two-coupled modes laser model. It is demonstrated that, depending on the cavity losses, different type of instabilities can arise. Low loss cavity favours stable continuous regime in a large range of pumping rates while high loss configuration permits the emergence of different self-pulsing instabilities

Instabilities in high power fiber lasers induced by stimulated Brillouin scattering

We investigate numerically different types of instabilities in a high loss Fabry–Perot laser cavity in presence of the stimulated Brillouin scattering. Our results reveal many interesting dynamical behaviors such as periodic, quasi-periodic and chaotic

High Repetition-rate Passively Mode-locked Fiber Lasers

Date du colloque&nbsp;: 03/2011</p

Lie Bialgebra Structures for Centrally Extended Two- Dimensional Galilei Algebra and their Lie-Poisson Counterparts

All bialgebra structures for centrally extended Galilei algebra are classified. The corresponding Lie-Poisson structures on centrally extended Galilei group are found.Comment: Eq. (11) changed, 15 pages, LaTeX fil

Analysis of Soliton Complexes in High Power Fiber Lasers

We consider a fibre laser operating in a regime where thousands of solitons coexist in the cavity. Because of the soliton interaction, different soliton patterns or complexes are generated depending on the laser parameters. We point out an analogy between soliton complexes and the states of the matter: soliton gas, soliton supersonic flow, soliton liquid, soliton polycrystal and soliton crystal

Intricate solitons state in passively mode-locked fiber lasers

We report a novel spontaneous soliton pattern formation in a figure-of-eight passively mode-locked erbium-doped double-clad fiber laser. It consists in a condensate phase in which there is almost periodic arrangement of alternate crystal and liquid soliton phases. Thanks to an adapted ansatz for the electric field, we perform a reconstruction allowing to clearly identify the soliton distribution along the cavity