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Internal nonlinear transmission in an Yb mode-locked fiber laser through bifurcations
摘要： Mode-locked fiber lasers are rich dynamical systems that may present several different types of pulsed operating modes, depending on external control parameters such as pump power. A systematic experimental characterization of such regimes is a challenging problem. Here single pulse regimes of ytterbium mode-locked fiber laser are explored and related to the nonlinear amplitude modulation affecting the pulses inside the laser cavity. To understand the full dynamics of this system, average power measurements (slow time scale) have been performed and compared to simultaneous time-resolved measurements (fast time scale). The average nonlinear transmission resulting from the amplitude modulation is measured, allowing to relate the transitions between dynamical regimes to the system’s nonlinearity.
关键词： Mode-locked fiber laser,Transmission curve,Nonlinear dynamics
更新于2025-09-12 10:27:22
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Fiber laser induced self-organizing structures of 316L stainless steel surface
摘要： When the micro-nano groove structure is processed on the surface of 316L stainless steel by a fiber laser, a self-organizing structure with regular distribution appears. After optimizing the processing parameters, the self-organizing structure with excellent quality can be formed in the groove. In order to further research the properties of the self-organizing structure, the large-area self-organizing structures with different spacings are processed. It is found by the characterization that when the spacing is 50 um, the contact angle of the large-area self-organizing structure is increased by 43.1% with respect to the smooth surface, and its wetting property changes from hydrophilicity to hydrophobicity. The component and the phase composition of the self-organizing structure were found to be consistent with the composition of the original material, and it is preliminarily concluded that the self-organizing structure is formed by the splashing flow of molten liquid in the oxidizing molten pool.
关键词： self-organizing structure,fiber laser,contact angle,component,316L stainless steel
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Supercontinuum Generation in a As <sub/>2</sub> S <sub/>3</sub> -Silica Nanospike Waveguide Pumped by Tm-Doped Fiber Laser
摘要： The development of compact bright supercontinuum (SC) sources is of particular interest, especially in the mid-IR where is a lack of suitable sources [1,2]. Here we report first results on SC generation in a As2S3-silica dual nanospike waveguide [3, 4] pumped in different multi-pulse regimes by a high-power femtosecond Tm-doped fiber laser mode-locked by nonlinear polarization evolution [5-7]. The experimental set-up is sketched in Fig. 1a. The central wavelength of the laser is 1890 nm and its repetition rate is 13 MHz. By tuning the polarization controllers (PC1 and PC2) in the ring cavity [8], the laser could be configured to operate in different multi-pulse regimes, namely noise-like pulses, soliton bunches and soliton “rain”. The pulse duration is 931 fs in both soliton regimes. The coherence time of the noise-like pulses is 228 fs. The pulses were free-space launched into the As2S3-silica dual nanospike waveguide designed to improve the launch efficiency in and out of the waveguide (~20%). The central uniform portion of the hybrid nanospike has a core diameter of 1.1 μm, the group velocity dispersion (GVD) curve of which is plotted in the inset of Fig. 1a. The pump wavelength is in the anomalous dispersion region between two zero dispersion wavelengths. The measured SC spectra are shown in Fig. 1b for the regimes of soliton bunches (top) and noise-like pulses (bottom). The results from the soliton “rain” regime (not shown here) and the soliton bunches regime are similar. In the soliton regime, sidebands originating from self-phase modulation are observed for a launched peak power of ~90 W, with the spectrum spanning from 1650 nm to 2200 nm. The launched peak power of the solitons was estimated by the pulse duration and the laser characteristics after taking into account the coupling efficiency. The black-dashed line in Fig. 1b plots the simulated spectrum at the output end of the dual nanospike, agreeing reasonably well with experiment. In the preliminary simulation, a single pulse with the same peak power (90 W) was launched into the model. When pumping the waveguide by noise-like pulses the spectrum barely broadens, probably due to the smaller peak power of a single pulse in the packet. In summary, we have achieved spectral broadening in a As2S3-silica hybrid waveguide pumped in different multi-pulse regimes at 1890 nm. It appears that soliton-like regimes are preferable for SC generation. The system is promising for realizing all-fiber broadband SC sources using well-defined femtosecond pulses, as well as investigating different mechanisms of SC generation in multi-pulse regimes.
关键词： mid-IR,Tm-doped fiber laser,supercontinuum generation,As2S3-silica nanospike waveguide,multi-pulse regimes
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Wide and Continuous Tunable Mode-Locked Erbium-Doped Fiber Laser Based on the Graphene Oxide
摘要： In addition to the artificial saturable absorber (SA) like the nonlinear polarization rotation (NPR), the investigation of peculiar soliton dynamics from passive mode-locked fiber laser (PML-FL) can be produced based on the semiconductor saturable absorber mirror (SESAM) and various nanomaterials, like the carbon nanotube (CNT), graphene, graphene oxide (GO), topological insulator (Bi2Se3) with lower mode-locked threshold. In comparison with other SAs, GO reveals various advantages including relative widely operation bandwidth, easy fabrication, low saturation intensity, ultrashort recovery time. For specific application, the wavelength tuning of PML-FL is required but is limited for the SESAM or CN. Recently, the wavelength tuning of mode-locked Er-doped fiber laser (EDFL) around 1570-1600 nm has been demonstrated based on graphene because of its relative wide absorption range. In this work, we demonstrated the fine tuning of emission peak wavelength of EDFL based on the GO/PVA film.
关键词： Erbium-doped fiber laser,mode-locked,graphene oxide,wavelength tuning
更新于2025-09-12 10:27:22
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[Laser Institute of America ICALEO? 2015: 34th International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - Atlanta, Georgia, USA (October 18–22, 2015)] International Congress on Applications of Lasers & Electro-Optics - Prediction of weld bead for fiber laser keyhole welding based on FEA
摘要： Fiber laser keyhole welding as a popular metal joining process has been widely used in a variety of applications especially automotive, shipbuilding and aerospace industries. Although process parameters determination based on experiments is the frequently used in the practical welding, it is often a very costly and time consuming. Accurately predicting the weld bead without expensive trial experiments has great theoretical significance and engineering value for welding process parameters pre-selection. An innovative volume heat source model was proposed for weld bead geometry prediction through finite element analysis (FEA) in fiber laser keyhole welding. The hybrid heat source model consists of a double ellipsoid heat source and a 3D Gaussian heat distribution model. To validate the effectiveness of the proposed heat source model, the fiber laser keyhole welding of the stainless steel SUS301L-HT has been carried out in this paper. The main three parameters, laser power (LP), welding speed (WS) and focal position (FP) have been taken into consideration as the design variables. Both of the predicted values from the FEA and back propagation neural network (BPNN) are compared with the experimental results. The FEA predicted results achieve good agreement with experimental results of weld bead shape and dimension and are better than BPNN predicted results. The objective variation trend is also analyzed by two prediction methods. From the discussion, it is revealed that the proposed prediction method of weld bead is effective for fiber laser keyhole welding process and replacing the expensive experiments.
关键词： Weld bead prediction,Keyhole welding,Fiber laser,FEA,BPNN
更新于2025-09-12 10:27:22
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170 mW-level mode-locked Er-doped fiber laser oscillator based on nonlinear polarization rotation
摘要： In our work, by optimizing the length of the cavity and using high-power home-made pump source, based on the commonly-used nonlinear polarization rotation (NPR) technique, we designed a stable all-fiber high-power Er-doped mode-locked laser successfully. The maximum average output power was as high as 174 mW under the pump power of 2659 mW. To our knowledge, 174 mW was a new record average output power of NPR based all-fiber mode-locked Er-doped fiber laser, which was much higher than the results reported previously. Our work will provide a significant reference for future demonstrations of high-power mode-locked Er-doped fiber lasers and promote the applications of mode-locked Er-doped oscillators.
关键词： Er-doped fiber laser,mode-locked,high-power,nonlinear polarization rotation
更新于2025-09-12 10:27:22
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Effect of Fiber Laser Irradiation on the Shear Bond Strength between Acrylic Resin and Titanium
摘要： Objectives. The aim of this study is to investigate the shear bond strength of an acrylic resin to titanium after different surface treatment methods. Material and Methods. A total of seventy-two disc-shaped specimens (10 mm × 10 mm × 2 mm) were prepared from titanium alloy. The specimens were randomly allocated to six equal groups: Group S (sandblasting), Group MP (metal primer), Group 10W (fiber laser 10 W), Group 20W (fiber laser 20 W), Group 10WMP (fiber laser 10 W+metal primer), and Group 20WMP (fiber laser 20 W+metal primer). All of the specimens were thermocycled up to 5000 cycles. After thermal cycling, a shear bond strength test was conducted. The shear bond strength data were analyzed with one-way ANOVA and Tukey’s post hoc pairwise comparisons (p < 0 05). Results. While the highest values were determined in Group MP, the lowest values were observed in Group S. Additionally, Group MP exhibited significantly higher shear bond strength values than any of the other groups (p < 0 05) except Group 10WMP. Similar results were observed between Group MP and Group 10WMP (p > 0 05). The groups in which a metal primer was applied (Group MP, 10WMP, and 20WMP) showed significantly higher values than Group S. The shear bond strength values of Group 10W and Group 20W were similar. Conclusions. The application of a metal primer significantly improved the bond strength of acrylic resin to titanium. Fiber laser application may be an alternative method to sandblasting for improving the bond strength of acrylic resin to titanium.
关键词： acrylic resin,fiber laser,titanium,shear bond strength,surface treatment
更新于2025-09-12 10:27:22
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Computational Doppler-limited dual-comb spectroscopy with a free-running all-fiber laser
摘要： Dual-comb spectroscopy has emerged as an indispensable analytical technique in applications that require high resolution and broadband coverage within short acquisition times. Its experimental realization, however, remains hampered by intricate experimental setups with large power consumption. Here, we demonstrate an ultrasimple free-running dual-comb spectrometer realized in a single all-fiber cavity suitable for the most demanding Doppler-limited measurements. Our dual-comb laser utilizes just a few basic fiber components, allows us to tailor the repetition rate difference, and requires only 350 mW of electrical power for sustained operation over a dozen of hours. As a demonstration, we measure low-pressure hydrogen cyanide within 1.7 THz bandwidth and obtain better than 1% transmittance precision over a terahertz in 200 ms enabled by an all-computational phase retrieval and correction algorithm. The combination of the setup simplicity, comb tooth resolution, and high spectroscopic precision paves the way for proliferation of frequency comb spectroscopy on a larger scale.
关键词： computational phase retrieval,Doppler-limited measurements,hydrogen cyanide,all-fiber laser,Dual-comb spectroscopy
更新于2025-09-12 10:27:22
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SnS2 Nanosheets for Er-Doped Fiber Lasers
摘要： Stannic sulfide (SnS2), a latterly developed two-dimensional (2D) material, has fascinated scientists because it can be widely applied to materials chemistry, biomedicine, photocatalysis, etc. Especially, SnS2 have advantages of adjustable band-gap and good oxidation resistance, which indicates that this material has promising potential in nonlinear optics. However, the light interaction with-SnS2 is rarely investigated. In this study, high-quality SnS2 nanosheets (Ns) developed through a liquid phase exfoliation approach have been applied in ultrafast photonics for nonlinear processes. This fabrication approach can greatly increase the damage threshold of the SnS2 saturable absorber (SA). Furthermore, the SnS2 SA device is applied to an erbium-doped fiber laser (EDFL) resonator to obtain soliton molecules with different order. Ultimately, 11th-order soliton molecules, the highest order of soliton molecules through SnS2, are generated with soliton separation of 8 ps and spectral modulation period of around 1 nm. The above experimental results indicate that SnS2 has broad application prospects in the fields of mode-locked fiber laser and optical fiber communication, etc.
关键词： soliton molecule,mode-locking,2D material,SnS2,Er-doped fiber laser
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Picosecond Widely-Tunable Mid-IR Source for Gas Detection
摘要： Portable and remote sensing solutions to detect the nature of gases in the air are highly demanded. In particular for instance, for the measurement of fire smoke or uncontrolled discharge on risk sites or on an accident including a vehicle transporting hazardous substances [1]. Spectroscopic-based solutions would need a widely-tunable and powerful mid-infrared compact laser source that could be used on field and scan a large number of species. In a previous research from A Puiu et al. [2], the authors described an interesting system for acetone detection at 3.3 μm. The principle used was differential absorption (DIAL) based on a tunable mid-IR source from 3 to 3.45 μm. This source was based on an optical parametric oscillator (OPO) pumped by a Nd:YAG laser. This laser delivered 3.4 mJ at 20 Hz repetition rate and with 7 ns pulse duration. With a set-up based on a gas chamber and mid-IR detection unit for direct absorption measurements the authors demonstrated the capability of their system for detecting acetone concentrations in the range from 1 to 10 % which is the typical level of concentration expected at the vicinity of a bomb factory for instance. Such results are really impressive for a system that is potentially transportable. However, regarding this aspect, mainly because of the footprint and weight of the laser system, portability of the detection unit was a bit limited. Thus, in our case we explored a solution based on a fiber laser pumped OPO. The developed picosecond laser source exhibits short pulses and narrow linewidth (0.4 cm-1). This fiber laser is based on a mode-locked oscillator [3], a Fiber Bragg Grating (FBG) mounted on a piezo electric element for wavelength tuning and several fiber amplifiers. The OPO system was provided by the company LASERSPEC (Belgium) and permits to reach a spectrum ranging from 2700 to 3500 nm. A typical experimental set-up was prepared for characterizing this source for gas sensing [4]. The OPO laser beam was split in two. One beam was sent to a FTIR spectrometer and the other one to an 18-cm-long cell containing the gas under study (See Fig. 1). Acetone detection was demonstrated for various concentrations (Fig. 2). FTIR measurements are in good agreement. In conclusion, we present promising results on acetone with detection levels down to 1% at 3.3 μm (2970 cm-1) using an absorption spectroscopy system based on a widely-tunable compact fiber laser / OPO source.
关键词： mid-IR source,fiber laser,OPO,widely-tunable,picosecond,gas detection
更新于2025-09-12 10:27:22