Soliton Fiber Laser Research Articles

Wide spectral and wavelength-tunable dissipative soliton fiber laser with topological insulator nano-sheets self-assembly films sandwiched by PMMA polymer.

Topological insulators have been theoretically predicted as promising candidates for broadband photonics devices due to its large bulk band gap states in association with the spin-momentum-locked mass-less Dirac edge/surface states. Unlike the bulk counterpart, few-layer topological insulators possess some intrinsic optical advantages, such as low optical loss, low saturation intensity and high concentration of surface state. Herein, we use a solvothermal method to prepare few-layer Bi₂Te₃ flakes. By sandwiching few-layer Bi₂Te₃ flakes with polymethyl methacrylate (PMMA) polymer, a novel light modulation device had been successfully fabricated with high chemical and thermal stabilities as well as excellent mechanical durability, originating from the contribution of PMMA acting as buffer layers that counteract excessive mechanical bending within the fragile Bi₂Te₃ flakes. The incorporation of the as-fabricated PMMA-TI-PMMA as saturable absorber, which could bear long-term mechanical loadings, into the fiber laser cavity generated the stable dissipative soliton mode-locking with a 3-dB spectral bandwidth up to 51.62 nm and tunable wavelength range of 22 nm. Our work provides a new way of fabricating PMMA-TI-PMMA sandwiched composite structure as saturable absorber with promising applications for laser operation.

Switchable multi-wavelength and dual-scale soliton fiber laser incorporating cascaded chirped fiber Bragg gratings

A simple scheme of a switchable multi-wavelength and dual-scale soliton fiber laser is proposed by cascading three chirped fiber Bragg gratings (CFBGs). By managing the cavity dispersion and controlling the losses of attenuators, quadruple-wavelength switchable pulses are generated, including one dissipative soliton (DS) and three conventional solitons (CSs). The central wavelength of the DS is 1565 nm with a pulse duration of 12.5 ps which can be compressed to ~571 fs after a 70 m single mode fiber external to cavity. Three CSs are achieved at 1539.5, 1544.5, and 1549.5 nm with pulse durations of 9.6, 8.7, and 8.8 ps, corresponding to the CFBG-based comb spectral filtering. These results demonstrate that the proposed method offers potential opportunities to exploit the flexibly switchable multi-wavelength CS/DS-pulse sources at picosecond and femtosecond scales.

Influences of pumping schemes on the properties of dissipative soliton in fiber lasers

Based on the extended scalar nonlinear Schrödinger equation, the influences of pumping schemes on the properties of dissipative soliton are investigated theoretically in passively mode-locked ytterbium-doped fiber laser with positive dispersion cavity. Results show that, under the conditions of the same initial total gain, the dissipative solitons obtained in the backward pumping fiber laser have the narrowest spectral width, shortest pulse duration and highest pulse peak power for the forward, backward and bidirectional pumping schemes, moreover, the linear fitting degree of pulse chirp is lowest. With the same gain saturation energy, the pulse energies of the dissipative solitons are equal for three pumping schemes, but the differences of output spectra and temporal waveforms increase as the gain saturation energy increases.

Formation and Energy Exchange of Vector Dark Solitons in Fiber Lasers

The mutual energy-exchange interactions in two orthogonally polarized components of vector dark soliton, which is automatically formed in a normal-dispersion fiber laser cavity in the presence of reverse saturable absorption, and dissipative cavity effects, had been theoretically and numerically investigated. Under specific cavity parameters, a vector dark soliton with periodic coherent energy exchange could be formed and well described by a semianalytic method. The multiple vector dark solitons with energy exchange were also demonstrated by combining gain bandwidth and a reverse saturable absorption effect.

Sideband-controllable soliton pulse with bismuth-based erbium-doped fiber

A sideband-controllable soliton mode-locked erbium-doped fiber laser is successfully demonstrated utilizing the nonlinear polarization rotation technique. The sidebands can be produced or suppressed by performing simple polarization light tuning with a polarization controller. It is believed that the elimination of the sidebands is due to the dispersive waves that are filtered out by the polarization-dependent isolator in the resonator. With the elimination of the Kelly sidebands, the obtained 3 dB bandwidth is 10.6 nm and the attainable pulse duration is 0.86 ps. In this experiment, it is proven that the existence of Kelly sidebands limits the attainable pulse duration.

Generation of bound states of pulses in a soliton laser with complex relaxation of a saturable absorber

A numerical model of a soliton fibre laser with a semiconductor saturable absorber mirror (SESAM), characterised by the complex dynamics of absorption relaxation, is considered. It is shown that stationary bound states of pulses can be formed in this laser as a result of their interaction via the dispersion-wave field. The stability of stationary bound states of several pulses is analysed. It is shown that an increase in the number of pulses in a stationary bound state leads eventually to its decay and formation of a random bunch. It is found that the bunch stability is caused by the manifestation of nonlinear self-phase modulation, which attracts pulses to the bunch centre. The simulation results are in qualitative agreement with experimental data.

Dissipative soliton mode-locked all-fiber laser with a broad spectral bandwidth

We demonstrate an all-fiber dissipative soliton fiber laser (DSFL) with a very broad spectral bandwidth by optimizing the cavity design of the fiber laser. Two different cavity schemes of the DSFL with simple cavity structures were built by employing a hybrid component, and their properties were investigated while varying the net cavity dispersion of the laser. By optimizing the cavity dispersion of the fiber laser, we achieved a DSFL that stably deliver linear chirped pulses with a pulse duration of 912.5 fs at a repetition rate of 52.2 MHz without additional pulse compression. The measured spectral bandwidth of the laser was 68 nm, which is the largest value ever reported for Er-doped DSFL oscillators.

Experimental and theoretical investigations of a tunable dissipative soliton fiber laser.

A tunable dissipative soliton fiber laser based on carbon nanotubes and the nonlinear polarization rotation (NPR) technique has been investigated experimentally and numerically for the first time to the author's best knowledge. The laser proposed delivers strongly chirped solitons with pulse duration of ∼220 ps and a spectral width of ∼5.6 nm. With the NPR-related filtering effect, the output pulses are wavelength tunable over the range from 1566 to 1593nm by adjusting the polarization controller (PC). Numerical results are in good agreement with experimental observations and clearly reveal that the tunable mode-locking operation is attributed to the variation of phase delay caused by the PCs.

Optimal design of higher energy dissipative-soliton fiber lasers

We have numerically investigated dissipative soliton (DS) fiber lasers using the cubic complex Ginzburg–Landau equation (CGLE), and analyzed the effects of different parameters, including the cavity length (CL), the spectral filter bandwidth (SFBW), nonlinear phase shifts (ΦNL), and the initial fields. The results showed that for any initial input fields, once the stable output pulse was formed, the output pulse energy would increase with decreasing CL, or increasing ΦNL. When the pump power and CL parameters were fixed, there existed an optimal SFBW for which the highest output pulse energy could be obtained. In order to obtain higher pulse energy in a DS fiber laser, one can first fix the CL according to the required repetition frequency, then optimize the SFBW, and finally, increase the pump power, which corresponds to increasing the ΦNL. In simulations, using optimal parameters, a single pulse with energy of ~50nJ, pulse duration of 10ps, dechirped pulse duration of 37fs, and pulse peak power of 1.4MW was obtained.

All-fiber mode-locked laser oscillator with pulse energy of 34 nJ using a single-walled carbon nanotube saturable absorber.

We demonstrate a dissipative soliton fiber laser with high pulse energy (>30 nJ) based on a single-walled carbon nanotube saturable absorber (SWCNT-SA). In-line SA that evanescently interacts with the high quality SWCNT/polymer composite film was fabricated under optimized conditions, increasing the damage threshold of the saturation fluence of the SA to 97 mJ/cm(2). An Er-doped mode-locked all-fiber laser operating at net normal intra-cavity dispersion was built including the fabricated in-line SA. The laser stably delivers linearly chirped pulses with a pulse duration of 12.7 ps, and exhibits a spectral bandwidth of 12.1 nm at the central wavelength of 1563 nm. Average power of the laser output is measured as 335 mW at an applied pump power of 1.27 W. The corresponding pulse energy is estimated to be 34 nJ at the fundamental repetition rate of 9.80 MHz; this is the highest value, to our knowledge, reported in all-fiber Er-doped mode-locked laser using an SWCNT-SA.

Polarized dissipative solitons in all-polarization-maintained fiber laser with long-term stable self-started mode-locking

We demonstrated a polarization-maintained dissipative soliton fiber laser. It was self-started and capable of outputting stable nanosecond mode-locked pulses through the nonlinear rotation inside fibers connected with a Faraday reflective mirror. The setup of the fiber laser ensured the output pulses with good polarization extinction, high pulse contrast, and quite good long-term stability against environmental disturbance. The mode-locked pulses were centered at 1030 nm with a narrow spectral bandwidth and had a pulse duration of 7 ns, while the pulse repetition rate could be varied from 1 to 8 MHz by setting the fiber cavity length. The output pulse energy reached 20 nJ at the repetition rate of 1 MHz.

Multisoliton complexes in fiber lasers

The formation of stationary and non-stationary pulse groups is regularly observed in multiple pulse soliton fiber lasers. The environment developed in this study for the flexible investigation of this phenomenon is based on the cavity comprising a semiconductor saturable absorber mirror (SESAM) with complex dynamics of absorption recovery and all-fiber dispersion management. The detailed experimental and theoretical considerations show that multiple pulsing in fiber systems offers numerous embodiments ranging from stationary bound states to chaotic bunches. The pulse interaction through the dispersive waves was found to produce a principal impact on the bound state formation. The stability and transformation of stationary bound states and bunch propagation have been also addressed.

Dissipative Soliton Generation and Amplification in Erbium-Doped Fibers Operating at 1.55 μm

We report on our recent developments on ultrafast pulse generation in erbium-doped fiber laser systems operating in the 1550 nm wavelength range. This work concerns the generation of ultrafast pulses from dissipative soliton fiber lasers featuring resonant saturable absorber mirrors as well as their amplification in highly efficient erbium-doped large-mode-area fibers. Different amplification schemes featuring all-fiber components are studied leading to the achievement of record pulse energy from a high repetition rate laser system. The system delivers 8 W of average power at 35 MHz repetition rate corresponding to 230 nJ pulse energy. After external compression, near transform-limited, 850 fs-long pulses are obtained. The pulse peak power exceeds 180 kW.

Mode-Locked Soliton Fiber Laser Using an Intracavity Polarization Maintaining Photonics Crystal Fiber

A passively mode-locked soliton fiber laser assisted with an interference filter is proposed and experimentally demonstrated. Self-started mode-locked soliton generation is based on the nonlinear polarization evolution (NPE). Of which, a polarization maintaining photonics crystal fiber (PM-PCF) is incorporated as an interference filter with tunable transmission bandwidth by controlling length of PM-PCF. In the experiment, we achieve a clean spectrum of dissipative soliton (DS) without sidebands, and a corresponding repetition rate of 6.554 MHz. Further adjusting the intracavity polarization with two polarization controllers (PCs) can transform the conventional DS to a vector DS with a rectangular spectrum. It is seen that the soliton operation regime can be dynamically managed by controlling the intracavity polarizations and net birefringence.

Observation of Three Bound States From a Topological Insulator Mode-Locked Soliton Fiber Laser

We report on the generation of three types of bound states in a topological insulator-based mode-locked fiber laser. Benefiting from the excellent performance of the polyvinyl alcohol-based topological insulator saturable absorber (SA), we have achieved three types of bound solitons. The bound states exhibit different features both in spectra and autocorrelation traces, which was found to be caused by the different peak intensities and pulsewidths of two closed pulses within the bound states. The experimental phenomena were further confirmed by the numerical simulations. The results reveal an alternative method to roughly estimate the constructed solitons within bound states and indicate that the topological insulator could serve as a highly nonlinear SA for observing soliton dynamics in fiber lasers.

280 GHz dark soliton fiber laser.

We report on an ultrahigh repetition rate dark soliton fiber laser. We show both numerically and experimentally that by taking advantage of the cavity self-induced modulation instability and the dark soliton formation in a net normal dispersion cavity fiber laser, stable ultrahigh repetition rate dark soliton trains can be formed in a dispersion-managed cavity fiber laser. Stable dark soliton trains with a repetition rate as high as ∼280 GHz have been generated in our experiment. Numerical simulations have shown that the effective gain bandwidth limitation plays an important role on the stabilization of the formed dark solitons in the laser.

Flexible graphene saturable absorber on two-layer structure for tunable mode-locked soliton fiber laser

Using a two-layer structure consisting of polyethylene terephthalate (PET) and polydimethylsiloxane (PDMS) to support graphene grown by chemical vapor deposition (CVD), we demonstrate a flexible integrated graphene saturable absorber (SA) on microfiber for passive mode-locked soliton fiber laser. This method can optimize the light-graphene interaction by using evanescent field in the integration structure. Moreover, the fiber laser with the in-line microfiber-to-graphene SA can realize the tunabilities of both the 3dB bandwidth of output optical spectrum and the pulse width of soliton. This tunable mode-locked soliton laser has potential applications in optical communication, optical microscopy, and so on.

1.55-μm wavelength ultrafast fiber oscillators and amplifiers

In this paper, we review our recent developments on ultrafast pulse generation in erbium-doped fiber laser systems operating in the 1550 nm wavelength range. This work concerns the generation of ultrafast pulses from dissipative soliton fiber lasers featuring resonant saturable absorber mirrors, as well as their amplification in highly efficient erbium-doped large-mode-area fibers. Different amplification schemes featuring all-fiber components are studied leading to the achievement of record pulse energy from a high repetition rate laser system.

Mode-locked soliton erbium-doped fiber laser using a single-walled carbon nanotubes embedded in polyethylene oxide thin film saturable absorber

We demonstrate a simple, compact, and low cost mode-locked erbium-doped fiber laser (EDFL) using a single-walled carbon nanotubes (SWCNTs) embedded in polyethylene oxide (PEO) thin film as a passive saturable absorber (SA). The film with a thickness of 50 μm was fabricated using a prepared homogeneous SWCNT solution with 0.1% loading percentage, which was mixed with a diluted PEO solution and casted onto a glass Petri dish to form a thin film by evaporation technique. The film is sandwiched between two fiber connectors to construct a SA, which is then integrated in an EDFL cavity to generate a self-started stable soliton pulses operating at 1558 nm. The soliton pulse starts to lase at pump power threshold of 17.6 mW with a repetition rate of 50 MHz, pulse width of 0.67 ps, average output power of 0.158 mW, pulse energy of 3.16 pJ, and peak power of 4.43 W.

Soliton Mode-Locked Erbium-Doped Fiber Laser Using Non-Conductive Graphene Oxide Paper

A femtosecond mode-locked soliton erbium-doped fiber laser (EDFL) is demonstrated using a commercially available nonconductive graphene oxide paper as a saturable absorber. The paper that is sandwiched between two fiber ferrules acts as a mode-locker. The EDFL generates a soliton mode-locked pulse train with a repetition rate of 15.62 MHz and pulsewidth of 680 fs. It is observed that the fiber laser has a low pulsing threshold as well as low damage threshold. The pulse energy and peak power are 0.0085 nJ and 11.85 W, respectively. The easy fabrication of graphene oxide paper should promote its potential application in ultrafast photonics.