High-energy Soliton Research Articles

Adjustable High-Energy Soliton Fiber Laser Based on a Spatial Alignment Structure

Adjustable High-Energy Soliton Fiber Laser Based on a Spatial Alignment Structure

Analysis of generation of high-energy dissipative solitons in all-normal-dispersion mode-locked photonic crystal fiber laser

In this research, an all-normal-dispersion mode-locked photonic crystal fiber laser (MLPCFL) is simulated. Three types of large-pitch PCFs with a small value of self-phase modulation coefficient are introduced and their fundamental characteristics are numerically investigated. They are then employed in the laser cavity and the performance of MLPCFL using these three different large-pitch PCFs is compared. According to the simulation results, as the hole-to-hole distance gets larger, the pulse spectrum profile changes from M-shape to parabolic and the temporal width of the pulses is also increased. Additionally, the simulation demonstrates that the presented laser has the potential to generate pulses with an energy of 450 nJ, if a 5 m length of passive PCF with Ʌ= 20 µm (Ʌ is hole-to-hole distance) is incorporated into the laser cavity. The results reveal that, by inserting a 1 m-long Yb-doped PCF with Ʌ= 20 µm at the output port of the laser, it becomes possible to generate pulses with an energy of 45 μJ and a peak power of 2.47 MW. The chirped output pulses from the amplifier are compressed after passing through the dispersion delay line and resulting in a reduction of the FWHM to 150 fs.

Comprehensive analysis of pure-quartic soliton dynamics in a passively mode-locked fiber laser

The understanding of soliton dynamics promotes the development of ultrafast laser technology. High-energy pure-quartic solitons (PQSs) have gradually become a hotspot in recent years. Herein, we numerically study the influence of the gain bandwidth, saturation power, small-signal gain, and output coupler on PQS dynamics in passively mode-locked fiber lasers. The results show that the above four parameters can affect PQS dynamics. Pulsating PQSs occur as we alter the other three parameters when the gain bandwidth is 50 nm. Meanwhile, PQSs evolve from pulsating to erupting and then to splitting as the other three parameters are altered when the gain bandwidth is 10 nm, which can be attributed to the existence of the spectral filtering effect and intra-cavity fourth-order dispersion. These findings provide new insights into PQS dynamics in passively mode-locked fiber lasers.

2.1 m, high-energy dissipative soliton resonance from a holmium-doped fiber laser system

Abstract We propose a 2.1 μm high-energy dissipative soliton resonant (DSR) fiber laser system based on a mode-locked seed laser and dual-stage amplifiers. In the seed laser, the nonlinear amplifying loop mirror technique is employed to realize mode-locking. The utilization of an in-band pump scheme and long gain fiber enables effectively exciting 2.1 μm pulses. A section of ultra-high numerical aperture fiber (UHNAF) with normal dispersion and high nonlinearity and an output coupler with a large coupling ratio are used to achieve a high-energy DSR system. By optimizing the UHNAF length to 55 m, a 2103.7 nm, 88.1 nJ DSR laser with a 3-dB spectral bandwidth of 0.48 nm and a pulse width of 17.1 ns is obtained under a proper intracavity polarization state and pump power. The output power and conversion efficiency are 0.233 W and 4.57%, respectively, both an order of magnitude higher than those of previously reported holmium-doped DSR seed lasers. Thanks to the high output power and nanosecond pulse width of the seed laser, the average power of the DSR laser is linearly scaled up to 50.4 W via a dual-stage master oscillator power amplifier system. The 3-dB spectral bandwidth broadens slightly to 0.52 nm, and no distortion occurs in the amplified pulse waveform. The corresponding pulse energy reaches 19.1 μJ, which is the highest pulse energy in a holmium-doped mode-locked fiber laser system to the best of our knowledge. Such a 2.1 μm, high-energy DSR laser with relatively wide pulse width has prospective applications in mid-infrared nonlinear frequency conversion.

Research Again Origin of the Asymmetry Between Matter and Antimatter — Energy Basic State Field of the Universe (∐)

In this paper, we introduce the Dirac equation and the hole theory of antiparticle generation, and the history of antiparticle discover. We study of the physical properties of the antiparticles; we point out that antigravity does not exist. We introduce the ideas of two talented physicists and Cabibbo theory which have important influence on the research of origin of the matter–antimatter asymmetry, we propose that the “Dirac energy sea” is compatible with Feynman’s idea that antiparticles are “time reversals” of particles and be used to analyze some cosmological problems. In this paper, we review and analyze a lot of literatures about the asymmetry research on matter and antimatter generation, the available data from astronomical observations, and we can conclude that: everything around us within [Formula: see text] light-years is made of matter the present-day observable universe most likely does not contain significant amounts of antimatter. We provide extensive analysis and introduce observation of antimatter from space, review massive literature on related research, it shows that the present theory cannot give a reasonable explanation for this problem, the origin of matter–antimatter asymmetry remains unknown, although continuing advances in theory and improved experiment limits have ruled out some scenarios, for example, sphaleron-leptogenesis at the electroweak phase transition in the Standard Model and so on. Based on Huang’s theory of the creating of cosmic matter and my idea of the existence of energy basic state field (EBSF) in the universe, we point out the quantum turbulence generated by quantum super-fluidity in the initial period of the formation of the universe, a large number of high-energy solitons (matter) are formed after the Big Bang, it is called Huang-yang mechanism, which is different from the mechanism of antimatter creation and annihilation. In this paper, we also research that the production and annihilation of positive and negative matter promote to further evolving nuclear synthesis to form nucleons. It is absolutely not a perfect mirror symmetry between matter and antimatter when universe creations primordial matter.

High energy and low noise soliton fiber laser comb based on nonlinear merging of Kelly sidebands.

Optical solitons in mode-locked laser cavities with dispersion-nonlinearity interaction, delivers pulses of light that retain their shape. Due to the nature of discretely distributed dispersion and nonlinearity, optical solitons can emit Kelly-sidebands via the frequency coupling of soliton and dispersive waves. In this paper, we generate a high-energy femtosecond laser comb, by using the intracavity Kelly radiations and 3rd order nonlinearities. By increasing the intracavity power, the soliton envelop and the Kelly-sidebands merge together via four-wave-mixing, forming a super-continuum spectrum, obtaining 3.18 nJ pulse energy. A supercontinuum span covering from 1100 nm to 2300 nm for further self-referenced f-2f stabilization can be directly achieved by using an amplification-free external supercontinuum technique. Our finding not only demonstrates a non-trivial frequency-time evolution based on 'erbium + χ(3)' nonlinear gains, but also offers a new opportunity to develop practically compact fiber frequency combs for frequency metrology or spectroscopy.

Fission free high-energy mode-locked soliton generation in an all-polarization-maintaining fiber laser

Fission free high-energy mode-locked soliton generation in an all-polarization-maintaining fiber laser

Entrainment, stopping, and transmission of microwave solitons of self-induced transparency in counter-propagating magnetized electron beam.

Based on numerical simulations of a boundary problem, we study various scenarios of microwave soliton formation in the process of cyclotron resonance interaction of a short electromagnetic pulse with a counter-propagating initially rectilinear electron beam taking into account the relativistic dependence of the cyclotron frequency on the electrons' energy. When a certain threshold in the pulse energy is exceeded, the incident pulse can propagate without damping in the absorbing beam, similar to the effect of self-induced transparency in optics. However, mutual motion of the wave and electrons can lead to some novel effects. For relatively small energy of the incident pulse, the microwave soliton is entrained by the electron beam opposite to the direction of the wave's group velocity. With an increase in the pulse energy, soliton stopping occurs. This regime is characterized by the close-to-zero pulse velocity and can be interpreted as a variety of the "light stopping." High-energy microwave solitons propagate in the direction of the unperturbed group velocity. Their amplitude may exceed the amplitude of the incident pulse, i.e., nonlinear self-compression takes place. A further increase in the incident energy leads to the formation of additional high-order solitons whose behavior is similar to that of the first-order ones. The characteristics of each soliton (its amplitude and duration) correspond to analytical two-parametric soliton solutions that are to be found from consideration of the unbounded problem.

Soliton Rectangular Pulses and Bound States in a Dissipative System Modeled by the Variable-Coefficients Complex Cubic-Quintic Ginzburg–Landau EquationSupported by the National Natural Science Foundation of China (Grant Nos. 11875008 and 12075034), and the Beijing University of Posts and Telecommunications Excellent Ph.D. Students Foundation (Grant No. CX2021129).

The complex cubic-quintic Ginzburg–Landau equation (CQGLE) is a universal model for describing a dissipative system, especially fiber laser. The analytic one-soliton solution of the variable-coefficients CQGLE is calculated by a modified Hirota method. Then, phenomena of soliton pulses splitting and stable bound states of two solitons are investigated. Moreover, rectangular dissipative soliton pulses of the variable-coefficients CQGLE are realized and controlled effectively in the theoretical research for the first time, which breaks through energy limitation of soliton pulses and is expected to provide theoretical basis for preparation of high-energy soliton pulses in fiber lasers.

CVD-Bi2Te3 as a saturable absorber for various solitons in a mode-locked Er-doped fiber laser

In this work, we report about high energy and various solitons' operation by using high-efficiency topological insulator bismuth telluride (Bi2Te3) nanofilms as broadband saturable absorbers in the passively mode-locked Er-doped fiber laser. The Bi2Te3 film was successfully synthesized by chemical vapor deposition (CVD). Excellent characteristics of the dark-bright pulse pairs, bright pulses, and multiharmonics have been investigated experimentally by adjusting the polarization state. At the same time, the maximum average output power was 40.18 mW, and the single-pulse energy was 20.91 nJ. As we all know, it is the various solitons of the first generation with large pulse energy in an Er-doped fiber laser with Bi2Te3 as saturable absorber. The experimental results show that CVD Bi2Te3 can be used as an excellent candidate in mode-locked fiber lasers.

High-energy soliton fission dynamics in multimode GRIN fiber.

The process of high-energy soliton fission is experimentally and numerically investigated in a graded-index multimode fiber. Fission dynamics is analyzed by comparing experimental observations and simulations. A novel nonlinear propagation regime is observed, where solitons produced by the fission have a nearly constant Raman wavelength shift and same pulse width over a wide range of soliton energies.

Graded index fiber as an all-fiber saturable absorber for large energy conventional soliton and dissipative soliton generation

In this work, we investigate the possibility of achieving nanojoule level pulse energy in an all-fiber Er-doped oscillator by using a graded index multimode fiber (GIMF) as the saturable absorber (SA). This GIMF-based SA demonstrates the desirable characteristics of high-power tolerance, large modulation depth of 29.6%, and small saturation fluence of ∼7.19×10−3 μJ/cm2, which contribute to the high-energy soliton generation. In the experiments, the oscillator generates stable ultrafast pulse trains with high pulse energy/average output power up to 13.65 nJ/212.4 mW in the anomalous regime and 6.25 nJ/72.5mW in the normal regime, which are among the highest energy/average output power values achieved by all-fiber Er lasers. The results obtained demonstrate that the GIMF-based SA can be used as an effective photonic device for high-energy wave-breaking free pulse generation.

Propagation of dark soliton interacting with domain wall in two immiscible Bose–Einstein condensates**Project supported by the National Natural Science Foundation of China (Grant Nos. 61565007, 11875149, 11747079, and 11874127), the Science Fund from the Department of Science and Technology of Jiangxi Province, China (Grant Nos. 20162BCB23049 and 20171ACB21045), the Youth Jinggang Scholars Program in Jiangxi Province, China, and the Program

Reflection and transmission are two behaviors of wave propagating to an interface. The immiscible binary mixtures of Bose–Einstein condensates can form the symmetry-breaking state, in which the domain wall on the center can serve as the interface. In this study, we explore in detail the propagation of a dark soliton interacting with the domain wall in the harmonic trap. We find that the low-energy dark soliton is easy to form the transmission and the high-energy dark soliton trends to reflect from the domain wall. Both reflection and transmission of dark soliton on the domain wall induce the sound radiation. But the sound radiation in the reflection derives from the collective oscillation of condensates, and it in the transmission comes not only from the collective oscillation, but also from the condensate filling in the dark soliton.

High-energy polarized soliton synthesis and its application to deep-brain 3-photon microscopy in vivo.

Here, we demonstrate a polarized high-energy soliton synthesis technique for deep-brain 3-photon microscopy (3PM) excited at the 1700-nm window. Through coherent combining, we generate linearly polarized high-energy solitons whose energy is twice as high than those of each linearly polarized solitons. Due to the nonlinear origin of signals, both measured 3-photon fluorescence signal and third-harmonic signals are thus boosted by ~8 times in a tissue phantom. Using this technique, we further demonstrate 3PM of sulforhodamine 101 labeled vasculature 1600 μm in the mouse brain in vivo, which cannot be achieved by single-polarized soliton excitation.

Clean optical solitons generation at the 1700 nm window in a short photonic-crystal rod

Tunable optical soliton generation from optical waveguides is especially suitable for multiphoton microscopy (MPM). Among the different waveguides, photonic-crystal (PC) rod has been mainly used for high-energy soliton generation at the 1700 nm window, which is promising for deep-tissue MPM. In order to obtain high-energy soliton, short PC rod is commonly used. This leads to dramatic overlap between the soliton spectrum and the residual pump or a second soliton spectrum and strong modulation of the soliton spectrum, when the pump pulse is relatively long, typical of energetic pump lasers for the PC rod. This spectral overlap and modulation make the spectral filtering of the solitons quite ambiguous and difficult. In this paper, we propose an effective method to generate clean solitons at the 1700 nm window, in a 44 cm short PC rod, by compressing the pump pulse width at 1550 nm. We demonstrate comparison experiments with both 500 and 175 fs pump pulse at 1550 nm. Our results clearly show that a shorter excitation pulse enables cleaner soliton generation at the 1700 nm window, in good agreement with theoretical expectations, which facilitates subsequent spectral filtering. We also demonstrate detailed comparison experiments and simulations of the filtered 1660 nm high-energy solitons. Compared with solitons generated by 500 fs pump pulse, the clean solitons generated by the 175 fs pump pulse also show clean temporal profiles manifested by both measured interferometric autocorrelation trace and simulated temporal intensity profile. We expect this technique will be beneficial for deep-tissue MPM excited at this window.

High-energy dissipative soliton resonance and rectangular noise-like pulse in a figure-9 Tm fiber laser

We experimentally demonstrate a direct generation of high-energy dissipative soliton resonance (DSR) and rectangular noise-like pulse (NLP) in a figure-9 thulium-holmium-doped mode-locked fiber laser. The pulse duration and average output power of the DSR can be tuned from 33.5 ns to 144.6 ns, and from 100.25 mW to 677.5 mW, respectively. The maximum of pulse energy is 713.2 nJ without wave breaking at pump power of 6.7 W, which is the highest energy of DSR in the region of 2 μm, to the best of our knowledge. In addition, the rectangular NLP with 452 nJ pulse bunch energy is also obtained.

Two-photon microscopy with a frequency-doubled fully fusion-spliced fiber laser at 1840 nm.

We introduce a fiber-based laser system providing 130fs pulses with 3.5nJ energy at 920nm at a 43MHz repetition rate and illustrate the potential of the source for two-photon excited fluorescence microscopy of living mouse brain. The laser source is based on frequency-doubling high-energy solitons generated and frequency-shifted to 1840nm in large mode area fibers. This simple laser system could unleash the potential of two-photon microscopy techniques in the biology laboratory where green fluorescent proteins with two-photon absorption spectrum peaking around 920nm are routinely used.

High-energy solitons generation with a nonlinear multimode interference-based saturable absorber

We demonstrate a mode-locked all-fiber Er-doped fiber laser using the structure of a step-index multimode fiber and a graded index fiber as a new saturable absorber (SA) based on nonlinear multimode interference. By bending the SA to a certain state, stable soliton pulses are obtained at a pump threshold of 65 mW. The oscillator generates soliton pulses at 1598 nm with a spectral bandwidth of 3.4 nm, 960 fs duration and a fundamental repetition rate of 9.789 MHz. The output power of 24 mW is achieved at the maximum pump power of 700 mW, corresponding to a single pulse energy of 2.44 nJ. To the best of our knowledge, this is the first time anyone has achieved the highest single pulse energy in a fiber laser with the SA at 1.5 µm to date. Moreover, the impact of diverse mode field diameters of graded index fiber on mode-locking behavior will also be discussed.

Soliton dynamics for a nonintegrable model of light-colloid interactive fluids

A nonintegrable model with the super-Kerr nonlinearity is investigated, which describes the light-matter interactions in a fluidic suspension of colloidal nanoparticles. Existence of the solitons with semi-analytic forms is shown for this model via the variational method. Numerical simulation is performed to demonstrate the good accordance with the variational analysis. Soliton interactions and soliton bound states are discussed in both the homogeneous and inhomogeneous media. In particular, inelastic interactions of two solitons are presented, and we find that there is an energy distribution $$P_\pm $$ , which has a dependence with the velocity of the high-energy solitons. Simulations also reveal that the maximum value of $$P_-$$ relates with the soliton energy and the model parameter $$\beta $$ . Moreover, two different patterns of the three-soliton interactions are depicted as manifestation of the nonintegrability.

High-energy and efficient Raman soliton generation tunable from 1.98 to 2.29 µm in an all-silica-fiber thulium laser system.

We demonstrate a compact, all-fiber-integrated laser system that delivers Raman solitons with a duration of ∼100 fs and pulse energy of up to 13.3nJ, continuously wavelength tunable from 1.98 to 2.29µm via Raman-induced soliton self-frequency shift (SSFS) in a thulium-doped fiber amplifier. We realize a >90% efficiency of Raman conversion, the highest reported value from SSFS-based sources, to the best of our knowledge. This enables us to achieve >10 nJ soliton energy from a 2.16 to 2.29µm range, the highest energy demonstrated above 2.22µm from an SSFS-assisted, all-fiber tunable single-soliton-pulse source, to the best of our knowledge. Our simple and compact all-fiber tunable laser could serve as an efficient ∼2 µm femtosecond source for a wide range of mid-infrared applications.