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We propose and demonstrate a passively mode-locked all-fiber laser utilizing a multimode interference effect in graded-index multimode fiber (GIMF). The mode-locking is obtained due to the Kerr effect in GIMF, which induces the intensity modulation inside the ring cavity laser. We obtain stable soliton mode-locked pulses at a center wavelength of 1574.1 nm, with a fixed repetition rate of 22 MHz and a pulse duration of 650 fs, when the pump power is changed in the range from 66.2 to 140.0 mW. The maximum average output power and pulse energy are recorded at 9.82 mW and 448 pJ, respectively, at a pump power of 140 mW. This proves that a nonlinear optical response in GIMF can be used as a new modulation mechanism for obtaining ultra-short pulses based on all-fiber ring cavity. [ABSTRACT FROM AUTHOR]

Short pulses are showing increasing importance in various industrial and scientific applications. Here, we exploit the saturable absorption of a ternary layered MAX-phase compound of Vanadium Aluminum carbide (V4AlC3) to produce mode-locked pulses in Erbium-doped fiber-laser (EDFL) cavity. The V4AlC3 composite thin film with a modulation depth of 24% is successfully obtained by embedding the commercial V4AlC3 powder into polyvinyl alcohol (PVA). It is integrated into an EDFL cavity, as a saturable absorber (SA), to generate a highly-stable mode-locked pulse, which operates at the 1559.8 nm wavelength. We successfully obtain the mode-locked pulse train with a fixed repetition rate of 1.8 MHz and a pulse width of 3.66 ps, as the pump power is set within a range from 73.1 to 108.1 mW. At the maximum pump power equal to 108.1 mW, the average output power, pulse energy, and peak power are 10.2 mW, 5.4 nJ, and 1.5 W, respectively. Overall, these results show the potential of V4AlC3 MAX-phase material to be used in ultrafast generation. The proposed approach is straightforward and can also be applied to operate in other wavelength regions. [ABSTRACT FROM AUTHOR]

We propose a MXene Ti3C2Tx thin-film and demonstrate as saturable absorber (SA) to generate mode-locked laser pulses. In constructing the SA, titanium carbide (Ti3C2Tx) powder obtained through a selective etching process is dispersed in polyvinyl alcohol (PVA) solution before the mixture is dried to form a thin film. A small piece of the film is placed between two fiber ferrules to form a SA device and added to an erbium-doped fiber laser (EDFL) cavity with a length of 106 m to produce mode-locked pulses. The mode-locked laser operates at 1561.2 nm with a repetition rate of 1.89 MHz and pulse width of 154 ns as the pump power is fixed within a range from 40.2 to 87.2 mW. At 87.2 mW pump power, the maximum average output power, pulse energy, and peak power were measured to be 11.85 mW, 6.24 nJ, and 40.7 mW respectively. [ABSTRACT FROM AUTHOR]

As typical soliton pulse sources, ultrashort-pulse fiber lasers offer excellent platforms for the investigation of soliton dynamics. On the basis of dispersive Fourier transform, we report the pulse evolution and dynamics of a pulsed erbium-doped fiber laser with plasmonic titanium nitride nanoparticles under different pump powers in two states: mode-locking and Q-switched mode-locking (QS-ML). In the QSML regime, the real-time evolution spectra exhibit a regular periodic change that corresponds to the Q-switching rate. The results of this study may stimulate further exploration of metal nitride materials for pulse generation in fiber lasers, which have widespread applications in science and technology. [ABSTRACT FROM AUTHOR]

We report the mode locking regime of dye laser pumped by 400 ns laser diode pulses. Three green laser diodes operating at 513 nm are used as the pump source. We obtain subnanosecond pulse trains using periodic 1 ns pulse modulation of the power-supply current through the pump diodes. The addition of a saturable absorber results in both a decrease in the pulse duration to 0.2 ns and a good reproducibility of the output radiation.. [ABSTRACT FROM AUTHOR]

We present an experimental demonstration of a passively mode-locked figure-eight fiber laser (F8L) based on a power-imbalanced nonlinear optical loop-mirror (PI-NOLM) comprising a section of 25 m long high-nonlinear fiber (HNLF) and a tunable attenuator (ATT). The asymmetric power, which results in different nonlinear phase shifts on the clockwise (CW) and counter-clockwise (CCW) directions, is achieved using an ATT. We greatly reduce the length of the nonlinear cavity, which can effectively diminish the interference from external environment. A balanced optical coupler (OC) and an ATT act as a tunable OC. So, a stable mode-locked pulse train with full width at half maximum (FWHM) of ∼571 fs and signal-to-noise ratio (SNR) of ∼60 dB is obtained. [ABSTRACT FROM AUTHOR]