Ph. Grelu

Phase-locked soliton pairs in a stretched-pulse fiber laser

We report the experimental observation of stable pulse pairs with a +/-pi/2 phase difference in a passively mode-locked stretched-pulse fiber ring laser. In our setup the stabilization of interacting subpicosecond pulses is obtained with a large range of pulse separations, namely, from 2.7 to 10 ps, without the need for external control.

Soliton pairs in a fiber laser: from anomalous to normal average dispersion regime

We report the observation of self phase-locked pulse pairs in a stretched-pulse fiber laser operating in the normal path-averaged dispersion regime. Numerical simulations agree with our experimental results. More insight is provided with a numerical comparison between intracavity profiles of pulse pairs in anomalous and in normal dispersion regimes.

Multisoliton states and pulse fragmentation in a passively mode-locked fibre laser

We report the observation of a novel feature in the pulse emission characteristics of a passively mode-locked fibre ring laser. In both anomalous and normal path-averaged dispersion regimes, we show switching from stationary multisolitons, which comprise a small number of pulses, to large soliton trains. The abrupt transition between the two emission regimes is manifested in both ways.

Fiber laser mode locked through an evolutionary algorithm

Mode locking of fiber lasers generally involves adjusting several control parameters, in connection with a wide range of accessible short-pulse dynamics. In this Letter, we experimentally demonstrate the ability of an evolutionary algorithm to prescribe a set of cavity parameters entailing specific self-starting mode locking. The prescribed parameters are applied to electrically driven polarization controllers, thus shaping the effective nonlinear transfer function at play within the fiber cavity. According to the specifications of the objective function used for the optimization procedure, various short-pulse regimes are obtained. Our versatile method represents an effective novel avenue for the exploration and optimization of nonlinear cavity dynamics.

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.

Near-field control of optical bistability in a nanocavity

We show here that the optical bistability of a nonlinear nanoresonator can be efficiently controlled by manipulating dynamically the resonance of the optical cavity with a near-field tip. We demonstrate experimentally that the operating regime of the nanocavity can be switched between the monostable and the bistable regimes. Finally, we propose an analytical model which provides a clear understanding of the whole nonlinear opto-mechanical system reported here.

Optical Soliton Molecules in Fiber Lasers

Recent experiments demonstrate that fiber laser cavities are able to support various multisoliton complexes, analogous to soliton molecules, which could have impact on optical information transmission or storage. These advances are guided by the concept of dissipative soliton.

Ultra-high repetition-rate-selectable passive harmonic mode locking of a fiber laser

The pursuit towards higher repetition rate pulse sources has accelerated recently, due to the strong need, in numerous applications, of pulse trains with gigahertz repetition rates. Considering their versatility and scalability, passively mode-locked fiber lasers present interesting potentialities in that respect. Especially promising for the development of ultra-high repetition rate lasers is the exploitation of the multi-pulsing operation under intense pumping power through the collective dissipative soliton dynamics of harmonic mode-locking (HML) [1]. Passively HML fiber lasers have reached 10 GHz [2]. Still, many factors affecting the regular distribution of multiple pulses all along the cavity remain unclear. In particular, the role of a continuous wave background to act as an efficient interaction mediator between pulses has been advanced [3].

Sub-nanosecond nonlinear pulse shaping in microfiber resonators

Thanks to their small size and large index contrast allowing for tight field confinement, optical microfibers are of great interest in nonlinear optics. Their properties have recently been exploited in various devices for supercontinuum generation, pulse compression [1] and third-harmonic generation [2]. Combining field confinement and field enhancement in a loop or knot resonator can result in low-threshold non-linear microfibre devices, in which pulse shaping effects and bistability can be obtained. Such a behaviour has already been observed at a power level of ten milliwatts with millisecond time response, in the case of thermally-induced non-linearity in silica microfibres [3]. In contrast, the quasi-instantaneous Kerr effect is suitable for the processing of pulses above the GHz range, but requires much higher power, of the order of several hundreds of watts [4]. In the present work, we discuss the conditions under which the Kerr effect dominates over the thermal effect in a silica microfibre resonator, present the experimental set-up we developed to reach these conditions, and the observation of sub-nanosecond pulse shaping that results.

Pulsating dissipative light bullets

Finding domains of existence for (3+1)D spatio-temporal dissipative solitons, also called “dissipative light bullets”, by direct numerical solving of a cubic-quintic Ginzburg-Landau equation (CGLE) is a lengthy procedure [1,2]. Variational approaches pave the way for quicker soliton solution mapping, as long as tractable trial functions remain suitable approximations for exact solutions [3,4].