Hybrid Mode-locked Fiber Laser Research Articles

Hybrid mode-locked fiber laser based on nonlinear optical loop mirror and manganese phosphorus triselenide (MnPSe3) coated arc-shaped fiber

This study investigates a hybrid mode-locked fiber laser incorporating manganese phosphorus triselenide (MnPSe3) saturable absorber and nonlinear optical loop mirror (NOLM), yielding profound insights into its potential and performance. The hybrid mode-locked laser showcased an output spectrum centered at 1549 nm with an expanded 3-dB bandwidth of 12.25 nm. It generates remarkably narrow pulses, with a pulse width of 240 fs. The mode-locking operates at a repetition rate of 5.71 MHz, with a high signal-to-noise ratio (SNR) of 58 dB, and achieves an average output power of 299 mW with a pulse energy of 52.36 nJ and peak power of 218 kW. These findings underscore the potential of the hybrid mode-locking configuration utilizing MnPSe3 to enhance mode-locked pulse generation significantly compared to the NOLM configuration.

Coexistence and competition: Double attractors in hybrid mode-locked fiber lasers

The hybrid mode-locking technique has been widely used in enhancing pulse quality, but the specific mechanism of hybrid mode-locking remains unclear. In this work, we experimentally investigate three pulse formation mechanisms in saturable absorbers (SA) and nonlinear polarization evolution (NPE) passively hybrid mode-locked fiber laser, which are SA domination, NPE domination, and SA-NPE co-domination switching and clarified the existent dynamic competition and cooperation between the two mode-locking mechanisms of the hybrid mode-locked fiber laser. The method of simulating the filtered gain spectrum with customized filtering is proposed, and the switching of pulse formation mechanisms is numerically investigated using the coupled Ginzburg–Landau equations. The presence of a double attractor subsystem in a hybrid mode-locked fiber laser is proposed and demonstrated. Our results deepen the understanding of hybrid mode-locked fiber lasers and provide experimental ideas for the study of multi-attractor coexistence.

Generation of sub-100 fs pulses from a SESAM-NPE hybrid mode-locked Yb-doped fiber laser at a fundamental repetition rate of 1.15 GHz.

Supercontinuum generation via direct pumping of unamplified high-repetition-rate, sub-100fs pulses with a pulse energy lower than 50pJ is superior in noise performance and features a high acquisition speed. We demonstrate a novel, to the best of our knowledge, gigahertz-repetition-rate, mode-locked Yb-doped fiber laser, where the hybrid mode-locking approach is employed. The laser has a low initiating threshold of 300mW and a broad mode-locking range of 600mW (300-900mW) in terms of pump power. The shortest obtained pulse width of the laser after compression is 95fs, and the highest output pulse energy is 92.9 pJ at a fundamental repetition rate of 1.15GHz. Moreover, the laser's output polarization states are switchable, and it has a polarization extinction ratio of 17.9dB.

Transient multi-soliton dynamics between adjacent-order harmonic mode-locking states in a hybrid mode-locked fiber laser

The buildup dynamics from noise-seeded relaxation oscillation to harmonic mode-locking (HML) solitons generation have been well investigated in ultrafast fiber lasers. However, the transient multi-soliton dynamics in higher-order HML states are still attractive yet largely unexplored. We reveal here that, the experimental observation of the multi-soliton dynamics including soliton beating dynamics, soliton annihilation, transient bound state, two-soliton resonance state, soliton splitting, and multi-soliton repulsion dynamics are analyzed by the emerging time-stretched dispersive Fourier transform (TS-DFT) technique. Particularly, the excessive intracavity energy result in the double-pulse pulsating with transient bound states and three types of soliton molecules states can be observed in the earlier and middle part of the transition process. Numerical results further reveal that several similar multi-soliton dynamics operating at stable 2nd and 3rd states could be caused by a fine tuning of the pump power level in a hybrid mode-locked laser. Our results unveil a diverse set of ultrafast transient process in fiber lasers, and open up new ways into obtaining and controlling the generation of high-repetition-rate ultrashort pulses in fiber lasers.

Real-time transition dynamics of harmonic mode-locking states with spectral filtering effect in a hybrid mode-locked fiber laser

We experimentally investigated the transition dynamics between 2nd and 3rd harmonic mode-locking states using the dispersive Fourier transform technology in a hybrid mode-locked fiber laser. Keeping the pump power unchanged and adjusting polarization controller to change intracavity-loss-dependent gain profile and the spectral filtering effect, a set of soliton dynamics induced by soliton interaction are revealed before the soliton splitting. Solitons undergo similar oscillation behaviors during the reverse decay process of the harmonic mode-locking order until one of the solitons disappears. In these transient dynamics, a significant wavelength shift phenomenon could be observed in the transition process of harmonic orders. The numerical results further show that intracavity spectral filtering effects play key role in the harmonic order transition dynamics process, consistent with experimental results. It provides new insights into the evolution and dynamics behavior in harmonic mode-locked soliton order conversion and its potential applications.

High-energy femtosecond pulse generation from a hybrid mode-locked large-mode-area Er:ZBLAN fiber laser.

We report a hybrid mode-locked fiber laser at 2.8 µm based on a large-mode-area Er:ZBLAN fiber. Reliable self-starting mode-locking is achieved via the combination of nonlinear polarization rotation and a semiconductor saturable absorber. Stable mode-locked pulses with a pulse energy of 9.4 nJ and a pulse duration of 325 fs are generated. To the best of our knowledge, this is the highest pulse energy directly generated from a femtosecond mode-locked fluoride fiber laser (MLFFL) to date. The measured M2 factors are below 1.13, indicating a nearly diffraction-limited beam quality. Demonstration of this laser provides a feasible scheme for the pulse energy scaling of mid-infrared MLFFLs. Moreover, a peculiar multi-soliton mode-locking state is also observed, in which the time interval between the solitons varies irregularly from tens of picoseconds to several nanoseconds.

Tunable and switchable single-/dual-wavelength Er-doped hybrid mode-locked fiber laser by dual-PMFs Lyot filter

Tunable and switchable single-/dual-wavelength Er-doped hybrid mode-locked fiber laser by dual-PMFs Lyot filter

Numerical analysis of hybrid mode-locking stability in a Ho-doped fiber laser.

We numerically study a hybrid mode-locked holmium-doped fiber laser based on the coupled nonlinear Schrödinger equations, by introducing nonlinear polarization rotation and saturable absorber in a same cavity. Maps of mode-locking states related to the intracavity wave-plates are created to evaluate the stability of mode-locking. Nonlinear polarization rotation imposes negative effect of linear absorption and even reverse saturable absorption to the pulses in the hybrid cavity. Saturable absorber compensates the negative effect from nonlinear polarization rotation, then consequently contributes to the stability of single-pulse mode-locking states. The extension of pulse time duration indicates the dynamic synergy between nonlinear polarization rotation and saturable absorber rather than the static combination mechanism of them.

Switching and coexistence of stretched pulse and dissipative soliton in a hybrid mode-locked fiber laser

We experimentally demonstrate a thulium–holmium co-doped hybrid mode-locked fiber laser, which can operate in two modes. One is the switch between stretched pulse and dissipative soliton, the other is the dual-wavelength mode-locking corresponding to the coexistence of stretched pulse and dissipative soliton. The optical spectra of the stable dual-wavelength mode-locking pulses centers at 1905 nm and 1946 nm respectively, and the corresponding pulse widths are 5.9 ps and 823 fs. In addition, the central wavelength is in the tunable range of 27 nm when the laser operates on a dissipative soliton regime.

Saturable absorber based on graphene for a hybrid passive mode-locked erbium-doped fiber laser

We proposed a hybrid passive mode-locked fiber laser based on a saturable absorber fabricated by coating a layer of graphene on a single-mode fiber with inscribed short waveguides. The hybrid mode-locked fiber laser operation is achieved by use of nonlinear polarization rotation and saturable absorption. The output pulses have the center wavelength of 1558 nm, 3-dB bandwidth of 4.6 nm, pulse width of 605 fs, repetition frequency of 20.8 MHz, and signal-to-noise ratio of 60 dB. Compared with the use of nonlinear polarization rotation mode locking alone, the pulse width is compressed by 211 fs, and the signal-to-noise ratio is improved by 5 dB. The advantages of hybrid mode locking mechanism include simple structure and convenient operation, which make the system attractive in ultrafast lasers.

Switching and Coexistence of Stretched Pulse and Dissipative Soliton in a Hybrid Mode-Locked Fiber Laser

Switching and Coexistence of Stretched Pulse and Dissipative Soliton in a Hybrid Mode-Locked Fiber Laser

Tunable and Switchable Single/Dual-Wavelength Er-Doped Hybrid Mode-Locked Fiber Laser with Dual-Pmfs Lyot Filter

Tunable and Switchable Single/Dual-Wavelength Er-Doped Hybrid Mode-Locked Fiber Laser with Dual-Pmfs Lyot Filter

Numerical study of a hybrid mode-locked erbium-doped fluoride fiber laser at 2.8 μm

We numerically investigate a hybrid mode-locked erbium-doped fluoride fiber laser in the mid-infrared region. Based on the coaction of nonlinear polarization rotation (NPR) and semiconductor saturable absorber mirror (SESAM), uniform mode-locked soliton pulse with 155 fs pulse duration, 14.78 kW peak power, and 2.29 nJ pulse energy can be achieved. For comparison, the single SESAM mode-locking and NPR mode-locking of the erbium-doped fluoride fiber laser are simulated, respectively. The effect of all kinds of parameters including gain fiber length, saturable energy of the gain fiber, linear cavity phase delay bias, and small-signal gain on the hybrid mode-locking laser are also investigated.

10GHz regeneratively mode-locked erbium-doped fiber laser combined with nonlinear amplifying loop mirror

Mode-locked fiber lasers can generate short pulses with a high repetition rate. It can be used in nonlinear optical imaging, photo-communication and other fields. Obtaining narrow pulses with high repetition frequency has become a hot research topic. In this article, we demonstrate a hybrid mode-locked fiber laser, which is a regeneratively mode-locked erbium fiber laser operating at 10 GHz, incorporating a nonlinear amplifying loop mirror to generate a 1.9 ps pulse sequence. This all-fiber laser with a high-repetition-rate and short pulses has the advantages of high stability and self-starting, which has a wide range of applications.

Generating narrow bandwidth pulses in a hybrid mode-locked fiber laser.

We demonstrate for the first time, to our knowledge, an all-fiber erbium-doped mode-locked laser in which mode-locking (ML) is realized by the combination of nonlinear polarization rotation and a saturable dynamic filtering effect, thereby generating nearly transform-limited ultrashort pulses with a pulse duration and spectral width of 45.2 ps and 0.0775 nm, respectively. The laser achieves both ML and harmonic ML by increasing the pump power. Simultaneously, the filtering function is maintained by the saturable dynamic induced grating (SDIG) throughout the power-modulation process. Furthermore, numerical simulations are used to analyze the pulse energy evolution in the cavity, revealing the advantages of hybrid ML in decreasing the pulse duration and time-bandwidth product under narrow filtering status. This work proposes a practical method to achieve ultrafast laser pulses with a narrow bandwidth, solving the problem that the SDIG has a hard time realizing a stable ML sequence.

Hybrid mode-locked fiber laser with Fe3O4 nanoparticles

As a typical zero-dimensional (0D) material, Fe3O4 nanoparticles have been extensively used in various fields because of their unique properties. In this work, Fe3O4 nanoparticles are prepared by the chemical co-precipitation technology, which show nonlinear optical response. By employing Fe3O4 nanoparticles as a slow saturable absorber (SSA) and nonlinear polarization evolution (NPE) as a fast saturable absrober (FSA), a self-started hybrid mode-locked Er-doped fiber (EDF) laser can be easily acquired, which generates the stable pulse train with pulse duration of 361 fs. Pulse duration decreased 35 fs when compared to use NPE SA. This research work suggests that Fe3O4 nanoparticles could be developed as potential SAs for ultrafast nano-photonics applications.

Generation and observation of ultrafast spectro-temporal dynamics of different pulsating solitons from a fiber laser.

As a universal phenomenon in nonlinear optical systems, pulsating behaviors of solitons have attracted increasingly more investigations. While pulsating solitons and their likely generation conditions had been widely theoretical studied, their detailed spectro-temporal dynamics had been hardly reported in experiments. Here, three types of pulsating solitons are experimentally generated and observed in a dispersion-managed, hybrid mode-locked fiber laser. By controllably generating such states through intracavity tuning and leveraging the dispersive Fourier transform technique that maps spectral information into the time domain, real-time ultrafast spectro-temporal evolutions of the pulsating behaviors are revealed. The numerical results further show the generation of the pulsating soliton could be caused by the intracavity spectral filtering effect, consistent with the experimental configurations. Our findings could provide further insights into the complex nonlinear dynamics in lasers and potential ways to the design such systems to deliver targeted soliton outputs for potential applications.

MXene saturable absorber enabled hybrid mode-locking technology: a new routine of advancing femtosecond fiber lasers performance

Abstract MXene is a promising two-dimensional (2D) material that is widely used in electro-photonic devices due to its unique properties. In this contribution, V2CT x , a novel MXene, was employed as a saturable absorber (SA) for hybrid passively mode-locked fiber lasers. An ultra-stable and self-starting mode-locked laser system with low threshold can be achieved using V2CT x nanosheets and nonlinear polarization evolution (NPE). Signal to noise ratio increased 13 dB compared with using only NPE SA. A 72 fs pulse duration is easily achieved from this hybrid mode-locked fiber laser system. To the best of our knowledge, this is the shortest pulse duration generated from the Yb-doped mode-locked fiber lasers using a hybrid or 2D SAs. This study proves that MXene V2CT x nanosheets can be developed as suitable SAs and served as potential advanced ultrafast photonic devices in the future.

Graphdiyne for Ultrashort Pulse Generation in an Erbium-Doped Hybrid Mode-Locked Fiber Laser

An erbium-doped hybrid passively mode-locked fiber laser based on few-layer graphdiyne (GDY) saturable absorber (SA) has been investigated for the first time. Hybrid mode-locked fiber laser is composed of nonlinear polarization rotation (NPR) technology and GDY-SA. The central wavelength, pulse width and repetition rate of the output pulse are 1530.7 nm, 690.2 fs and 14.7 MHz, respectively. Compared with the passively mode-locked pulse laser with GDY-SA or NPR technology alone, the output pulse width of hybrid passively mode-locked fiber laser is reduced more than 50 fs. It is demonstrated that the performance of GDY can be potentially applied in ultrafast laser.

Pump- and temperature-induced repetition frequency response study in hybrid mode-locked erbium fiber laser with distributed polarizer

We report a study on pump- and temperature-induced repetition frequency response in hybrid mode-locked stretched-pulse erbium fiber laser with distributed polarizer. For the first time to the best of our knowledge, we have shown frequency-dependent loss (FDL) contribution to pump-induced repetition frequency response behavior. FDL originates from wavelength-dependent saturation of nonlinear polarization evolution (NPE) mechanism which is inherent to stretched-pulse regime of operation. We have proposed an analytical model adequately describing NPE influence on pump-induced repetition frequency response. As it is observed, NPE-induced contribution substantially dominates over other physical perturbations leading to strictly different pump-induced repetition frequency response behavior compared to erbium fiber soliton laser.