Hysteresis phenomenon and multistability in figure-of-eight microstructured fiber laser

We report a theoretical investigation of multi-pulse emission of a microstructured figure-ofeight fiber laser operating in passive mode-locking. The proposed laser is mode locked by the nonlinear amplifying loop mirror (NALM). We study, in this paper, the hysteresis dependence and the number of pulses in steady state as a function of both the small signal gain and the nonlinear coefficient of microstructured fiber. The numerical simulation confirms that the pulse splitting is a consequence of the energy quantization in anomalous dispersion. Moreover, our results suggest that the hysteresis phenomenon is an intrinsic feature of the mode-locked fiber lasers independently of the exact mode-locking mechanism. Finally, we identify that the nonlinear coefficient of microstructured fiber plays a key role in the formation of multi-soliton

Control of the square pulse properties in figure-of-eight microstructured fiber laser

We numerically analyze the square pulse emission from a passively mode-locked figure-of-eight microstructured optical fiber laser. Numerical simulations demonstrate that the high nonlinearity of the microstructured fiber plays a key role in the output pulse duration. A dual-stage erbium-doped fiber amplifier has been used in the cavity. The first amplifier, localized in the nonlinear amplifying loop mirror, allows control of the pulse width, while the second amplifier in the unidirectional ring allows variation of the amplitude without affecting the pulse width. Our results give some physical insight to the square pulse formation and the generation of high-energy pulses. Our numerical model provides a general approach to control the properties of a square pulse, and hence could be of great importance for the design of practical high-energy fiber laser systems

Impact of power sharing method on battery life extension in HESS for grid ancillary services

Hybrid energy storage system (HESS) based on Li-ion and supercapacitor (SC) can play a potential role to stabilise the grid by providing the fast frequency ancillary services. The SC helps to reduce the battery charge/discharge stress and hence assists to extend the battery lifespan. The power sharing method (PSM) is the heart in control part to improve the HESS performance and reduce the battery stress. This paper proposes a hybrid PSM and investigates its impact on battery life extension along with its relation to the system design and regulation signal. The performance of hybrid PSM is compared with three other PSMs (low pass filter, first and second rule based) in a 10 MW / 10 MWh full-active parallel HESS for frequency regulation service in two networks: UK (national grid) and USA (PJM). Considering maximum possible battery lifetime up to 25 years, result shows that the hybrid PSM approach allows a degree of better performance for both grid while the sharing of SC is kept maximum 2.0% and 2.5% (for US and UK grid respectively) of the HESS capacity. This study also analyses the impact of PSM on shared capacity and design of HESS for different grid regulation signals

Widely tunable, narrow line width and low optical noise continuous-wave all fiber Er:Yb co-doped double-clad ring laser

In this paper, we report a widely tunable, narrow linewidth, low noise continuous-wave double-clad Er:Yb doped fiber ring laser. Tunability is demonstrated in wide range spanning from 1520 to almost 1620 nm covering the C and L spectral bands. The cavity design is optimized in order to achieve the largest tuning range with very high optical signal-to-noise ratio (SNR). The output coupling ratio greatly influences the tuning range of the laser while the position of the spectral filter determines the SNR. The obtained laser exhibits a tuning range over 98 nm with a nearly constant SNR of about 58.5 dB

L-Band Harmonic Mode Locking of Single-, Two-, and Three-Soliton Bunches from C-Band Amplifier in a Figure-of-Eight Fiber Laser

We report the experimental emission above 1.6 μm of harmonic mode locking of single-, two-, and three-soliton bunches in a C-band Er:Yb codoped silica fiber laser. The laser cavity consists of two connected fiber loops in the figure-of-eight configuration. In such a system the mode-locking regime arises spontaneously due to the nonlinear optical loop mirror, which acts as a saturable absorber. The 1.6 μm oscillation is enhanced by minimizing the linear intra-cavity losses. Depending on the pump power and the polarization controllers, the laser generates harmonic mode locking above 1.6 μm containing patterns with one, two or three pulses. These two last regimes have not been achieved so far at a long-wavelength range

Laser à fibre dopée erbium à 1600 nm. Fonctionnement continu et verrouille en phase

L\u27objectif de cet article est de démontrer la possibilité de faire osciller à 1.6 µm un amplificateur à fibre double gaine dopée erbium opérant dans la bande C, en ajustant les pertes intra-cavité. Deux configurations de cavité ont été utilisées, une cavité en anneau et une cavité en forme de huit. Dans les deux cas, il est possible d\u27obtenir l\u27oscillation à 1.6 µm en continu ou bien en impulsions ultra-courtes

On spin-rotation contribution to nuclear spin conversion in C_{3v}-symmetry molecules. Application to CH_3F

The symmetrized contribution of E-type spin-rotation interaction to conversion between spin modifications of E- and A_1-types in molecules with C_{3v}-symmetry is considered. Using the high-J descending of collisional broadening for accidental rotational resonances between these spin modifications, it was possible to co-ordinate the theoretical description of the conversion with (updated) experimental data for two carbon-substituted isotopes of fluoromethane. As a result, both E-type spin-rotation constants are obtained. They are roughly one and a half times more than the corresponding constants for (deutero)methane.Comment: 13 pages with single-spacing, REVTeX, no figures, accepted for publication in <J. Phys. B