Faouzi Bahloul

Generation of high energy square-wave pulses in all anomalous dispersion Er:Yb passive mode locked fiber ring laser.

We have experimentally demonstrated square pulses emission from a co-doped Er:Yb double-clad fiber laser operating in anomalous dispersion DSR regime using the nonlinear polarization evolution technique. Stable mode-locked pulses have a repetition rate of 373 kHz with 2.27 µJ energy per pulse under a pumping power of 30 W in cavity. With the increase of pump power, both the duration and the energy of the output square pulses broaden. The experimental results demonstrate that the passively mode-locked fiber laser operating in the anomalous regime can also realize a high-energy pulse, which is different from the conventional low-energy soliton pulse.

1.6 μm emission based on linear loss control in a Er:Yb doped double-clad fiber laser

Based on the control of the linear losses of the cavity, we demonstrate the possibility to achieve filterless laser emission above 1.6 μm, from a C-band double-clad Er:Yb doped fiber amplifier. The concept is validated in both continuous wave and mode-locked regimes, using a figure-of-eight geometry. A unidirectional ring cavity is also tested in the continuous regime. Spectral properties of laser emissions are characterized as a function of the intracavity linear losses.

10 μJ dissipative soliton resonance square pulse in a dual amplifier figure-of-eight double-clad Er:Yb mode-locked fiber laser

We demonstrate experimentally a double-clad Er:Yb co-doped dual amplifier passive mode-locked figure-of-eight fiber laser that generates high energy, width, and amplitude tunable dissipative soliton resonance square pulses. In our laser system, each loop contains an amplifier that controls a characteristic of the output pulse. The amplitude and width of the output beam can be controlled continuously but, dependently, according to the pump power of each amplifier. The pulse width can be tuned in a range of almost 360 ns while the peak power varies from 8 to 120 W. On maximum possible pumping from both sides without having a pulse break, we report square pulses with 10 μJ energy per pulse with a signal-to-noise ratio of 60 dB.

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

Abstract. 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.

Adiabatically tapered microstructured mode converter for selective excitation of the fundamental mode in a few mode fiber.

We propose a new technique to selectively excite the fundamental mode in a few mode fiber (FMF). This method of excitation is made from a single mode fiber (SMF) which is inserted facing the FMF into an air-silica microstructured cane before the assembly is adiabatically tapered. We study theoretically and numerically this method by calculating the effective indices of the propagated modes, their amplitudes along the taper and the adiabaticity criteria, showing the ability to achieve an excellent selective excitation of the fundamental mode in the FMF with negligible loss. We experimentally demonstrate that the proposed solution provides a successful mode conversion and allows an almost excellent fundamental mode excitation in the FMF (representing 99.8% of the total power).

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

We report a theoretical investigation of multi-pulse emission of a microstructured figure-of-eight 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.

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.

Exhaustive study of dissipative soliton resonance in a dual amplifier passively mode-locked fiber laser

We have proposed an exhaustive experimental study of dissipative soliton resonance in a double clad Er:Yb co-doped dual amplifier passively mode-locked figure-of-eight fiber laser. By adjusting the pumping powers of the amplifiers, both the amplitude and width of the output square-wave pulse can be tuned continuously. Moreover, some other key parameters such as the net cavity dispersion and the coupling ratio between the two loops of the cavity have been studied.

Route to high-energy dissipative soliton resonance pulse in a dual amplifier figure-of-eight fiber laser

We present a widely adjustable high energy square pulse laser operating in DSR in a passively mode-locked F8L using dual Er:Yb co-doped double clad amplifiers. By manually controlling the power of each amplifier, the pulse width can be varied in a range of 360 ns without generating multi-pulsing instabilities. To ensure that DSR would dominate the modelocking mechanism, we use a 1.5 km standard single-mode fiber in the cavity. At a maximum pumping power, the laser generated square pulses with 416 ns duration and an average output power of about 1.33 W with a repetition frequency of 133 KHz corresponding to a record pulse energy of 10 μJ.

High energy square-wave generation from an Er:Yb passive mode-locked fiber ring laser

Based on the dissipative soliton resonance occurring in highly anomalous dispersion regime, we have demonstrated the emission of highly energetic square-wave pulses from the Er:Yb doped double clad fiber laser passively mode-locked through nonlinear polarization evolution. In contrast with the classical soliton regime, when the pumping power increases the pulse broadens and its energy increases, both linearly. Experimental results exhibit a stable mode-locking with single pulse energy as high as 2.27 μJ, a pulse duration of about 200 ns and an average output power of 850 mW.