Dissipative Solitons in Fibre Lasers

Interdisciplinary concept of dissipative soliton is unfolded in connection with ultrafast fibre lasers. The different mode-locking techniques as well as experimental realizations of dissipative soliton fibre lasers are surveyed briefly with an emphasis on their energy scalability. Basic topics of the dissipative soliton theory are elucidated in connection with concepts of energy scalability and stability. It is shown that the parametric space of dissipative soliton has reduced dimension and comparatively simple structure that simplifies the analysis and optimization of ultrafast fibre lasers. The main destabilization scenarios are described and the limits of energy scalability are connected with impact of optical turbulence and stimulated Raman scattering. The fast and slow dynamics of vector dissipative solitons are exposed

Stochastic anti-resonance in a fibre Raman amplifier

Stochastic anti-resonance, that is resonant enhancement of randomness caused by polarization mode beatings, is analyzed both numerically and analytically on an example of fibre Raman amplifier with randomly varying birefringence. As a result of such anti-resonance, the polarization mode dispersion growth causes an escape of the signal state of polarization from a metastable state corresponding to the pulling of the signal to the pump state of polarization.This phenomenon reveals itself in abrupt growth of gain fluctuations as well as in dropping of Hurst parameter and Kramers length characterizing long memory in a system and noise induced escape from the polarization pulling state. The results based on analytical multiscale averaging technique agree perfectly with the numerical data obtained by direct numerical simulations of underlying stochastic differential equations. This challenging outcome would allow replacing the cumbersome numerical simulations for real-world extra-long high-speed communication systems

Raman polarizer based on a fiber with a random birefringence

Summary form only given. Raman polarizers are devices able to amplify and simultaneously repolarize optical signals, exploiting the polarization attraction phenomenon induced by the Raman gain anisotropy [1, 2]. To characterize the degree of polarization (DOP) of the signal as a function of the Raman gain (G) in the case of the co-propagating pump and signal pulses, the following formula for ideal Raman polarizer has been recently derived [1]: DOP = 1 - G-1.Detailed experimental study demonstrated the limited validity of this formula in the context of the missed DOP dependence on polarization mode dispersion (PMD) parameter Dp and the random birefringence correlation length Lc [3,4]. Here for the first time we develop a new model of a Raman polarizer that matches the experimental data by accounting for a fiber random birefringence properties in terms of parameters Dp and Lc. Based on our previous model of a fiber Raman amplifier [3,4] utilizing rigorous technique of averaging over the random birefringence of fiber in the case of negligible pump depletion, we derive the following equations for DOP as function of G, Dp and Lc

Rogue waves and mode locking driven by Vector Resonance Multimode instability

Modulation instabilities discovered more than fifty and hundred fifty years ago created since then a framework for study complexity of different wave phenomena including turbulence and rogue waves. Using Erbium-doped fiber laser without any previously studied mode-locking mechanisms, here for the first time we demonstrate both experimentally and theoretically a new type of modulation instability, namely Vector Resonance Multimode Instability, leading to tunability of the laser dynamics from turbulence including rogue waves to the stable pulse train similar to the laser mode-locking regime

Temporal scaling of optical rogue waves in unidirectional ring fiber laser

A fiber mode-lock laser allows generation of the optical rogue wave (ORW) at different time scales. The criteria for distinguishing between them is a comparison of the event lifetime with the main characteristic time of the system. The characteristic time can be estimated from the decay of an autocorrelation function (AF). Thus, in comparison with AF characteristic time, fast optical rogue wave (FORW) events have duration less than the AF decay time and it appeared due to pulse-pulse interaction and nonlinear pulses dynamics. While slow optical rogue wave (SORW) have a duration much more longer than the decay time of the AF which it papered due to hopping between different attractors. Switching between regimes can be managed by change the artificial birefringence that induced in a laser cavity. For understanding the role playing by the periodical amplification and the resonator, we have performed an unidirectional fiber laser experiments without a saturable absorber. This laser experiment allowed to generate of most of the RW patterns which were either observed experimentally or predicted theoretically. In this way, we have observed the generation of an FORW along with SORW under similar conditions. Most of the patterns were found to be mutually exclusive which means that only one RW mechanism was realized in each regime of generation

Bright and dark vector rogue waves

For an Erbium-doped mode locked fibre laser, we demonstrate experimentally a new type of vector rogue waves (RWs) emergence of which is caused by the coherent coupling of the orthogonal states of polarisation (SOPs). Unlike weak interaction between neighbouring dissipative solitons for the soliton rain, this creates a new type of the energy landscape where the interaction of the orthogonal SOPs leads to polarisation trapping or escapes from the trapping triggered by polarisation instabilities and so results in the pulse dynamics satisfying criteria of the 'dark' and 'bright' RWs. The obtained results, apart from the fundamental interest, can provide a base for development of the rogue waves mitigation techniques in the context of the applications in photonics and beyond

Vector rogue waves in a carbon nanotube mode-locked fiber laser

Summary form only given. Mechanisms of rogue waves (RWs) emergence have been extensively studied in fiber lasers with nonlinearly driven cavities [1], Raman fiber amplifiers and lasers [2], and fiber lasers via modulation of the pump [3]. Previously, it has been found that RWs can be emerged because of soliton-soliton interaction through the overlapping of their tails or soliton-dispersive wave interaction. The result of these interactions is a coupling enhancement that leads to chaotic pulse bunching in the form of soliton rain at the time scale of a round-trip time in a high pump power (800 mW) [4]. Such interaction can be controlled by the pump power modulation or/and by injecting a weak seeding signal and noise. Here, we report for the first time the observation of the soliton rain and soliton-soliton interaction that leads to the optical rogue wave emergence in a carbon nano-tube saturable absorber mode-locked fiber laser at low pump power (140mW) without pump modulation or injecting a weak signal and noise to the laser cavity. As we shown recently [5] that by tuning the interaction of two orthogonal-states of polarization (SOP) of the in-cavity birefringent and also the pump SOP whereas the polarization instability leading to the emergence of different optical RW events

Bright-dark rogue wave in mode-locked fibre laser

Rogue waves (RWs) are statistically rare localized waves with high amplitude that suddenly appear and disappear in oceans, water tanks, and optical systems [1]. The investigation of these events in optics, optical rogue waves, is of interest for both fundamental research and applied science. Recently, we have shown that the adjustment of the incavity birefringence and pump polarization leads to emerge optical RW events [2-4]. Here, we report the first experimental observation of vector bright-dark RWs in an erbium–doped stretched pulse mode-locked fiber laser. The change of induced in-cavity birefringence provides an opportunity to observe RW events at pump power is a little higher than the lasing threshold. Polarization instabilities in the laser cavity result in the coupling between two orthogonal linearly polarized components leading to the emergence of bright-dark RWs. The observed clusters belongs to the class of slow optical RWs because their lifetime is of order of a thousand of laser cavity roundtrip periods

Polarization attractors driven by vector soliton rain

Soliton rain is a bunch of small soliton pulses slowly drifting near the main pulse having the period of a round trip. For Er-doped fiber laser mode-locked by carbon nanotubes, for the first time, we demonstrate both experimentally and theoretically a new type of polarization attractors controllable by vector soliton rain. With adjusting the pump power, vector soliton rain takes the form of pulses with rotating states of polarization which enable transforming slowly evolving trajectories on the Poincaré sphere from the double-scroll spiral to the circle. The obtained results on controlling complex multisoliton dynamics can be of interest in laser physics and engineering with potential applications in spectroscopy, metrology, and biomedical diagnostics

Bound state vector solitons with locked and precessing states of polarization

We report experimental observation of new tightly and loosely bound state vector solitons with locked and precessing states of polarization in a carbon nanotube mode locked fiber laser in the anomalous dispersion regime