- 标题
- 摘要
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- 实验方案
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All polarization-maintaining passively mode-locked Yb-doped fiber laser: pulse compression using an anomalous polarization-maintaining photonic crystal fiber
摘要： We report the generation of short pulses at 1 μm using an all-polarization-maintaining (PM) fiber configuration. The pulses are provided by an all normal-dispersion Fabry-Perot Yb-doped cavity and are compressed with an anomalous polarization-maintaining photonic crystal fiber (PM PCF). Opposed to standard configurations; here the filtering action is solely performed by the finite bandwidth of the gain medium. The laser generates 8 ps width sech2 profile pulses at 1046.8 nm with a -10 dB bandwidth of 5.9 nm. After compression using the PM PCF, pulses with an FWHM of 3 ps were obtained, limited by the actual value of the available anomalous dispersion. We also report the changes in the output light pulses when both the net-normal dispersion of the cavity and the medium gain length were varied. We found that the lack of a specific filter within the cavity does not deteriorate the performance as compared with previous works.
关键词： dissipative solitons,photonic crystal fibers,fiber laser,polarization maintaining
更新于2025-09-16 10:30:52
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Bright–dark soliton dynamics and interaction for the variable coefficient three-coupled nonlinear Schr?dinger equations
摘要： Under investigation in this paper is the variable coefficient three-coupled nonlinear Schr?dinger (CNLS) equations, which govern the dynamics of solitonic excitations along three-spine α-helical protein with inhomogeneous effect. Via the Hirota method and symbolic computation, the exact two-bright-one-dark (TBD) and one-bright-two-dark (BTD) soliton solutions are constructed analytically. The propagation properties are discussed for TBD and BTD solitons when the variable coefficient is a hyperbolic secant function. Figures are plotted to reveal the following interactions of TBD and BTD two solitons: (1) Evolution without interactions of double-parabola-shaped solitons, of double-S-shaped solitons and of parabola-S-shaped solitons; (2) Evolution with periodic interaction of double-parabola-shaped solitons and of parabola-S-shaped solitons; (3) Collision of double-S-shaped solitons and of parabola-S-shaped solitons.
关键词： bright–dark solitons,Hirota bilinear method.,interaction,Three-coupled variable-coefficient nonlinear Schr?dinger equations
更新于2025-09-16 10:30:52
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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) - Observation of Laser-Cavity Solitons in Micro-Resonators
摘要： Optical frequency combs based on micro-cavity resonators, also known as ‘micro-combs’, are ready to achieve the full capability of their bulk counterparts but on an integrated footprint [1]. They have enabled major breakthroughs in spectroscopy, communications, microwave photonics, frequency synthesis, optical ranging, quantum sources and metrology. Of particular relevance was the recent experimental implementation of temporal cavity-solitons [2,3]. Temporal cavity-solitons in micro-resonators are described by the well-known Lugiato-Lefever equation. Currently, these self-localised waves form on top of a strong background of radiation, usually containing 95% of the total power [4] and require active control of an external driving laser – a complex process which limits the choice of fundamental parameters such as the repetition-rate. Developing simple methods for controlling and generating highly efficient, self-localised pulses is one of the most compelling challenges to overcome, in anticipation of the widespread use of micro-combs outside of laboratory environments. Here we report the discovery of micro-comb laser cavity-solitons, which are the most efficient class of cavity-solitons because they are intrinsically background-free. Laser cavity-solitons have previously underpinned major breakthroughs in other systems, e.g. for the realisation of efficient semiconductor lasers [5]. By merging their properties with the physics of both micro-resonators and multi-mode systems, we provide a fundamentally new paradigm for the generation, stabilisation and control of self-localised optical pulses in micro-cavities. Our design is inspired to the filter-driven four-wave mixing scheme [6], which is based on a nonlinear micro-cavity nested in a larger fibre-cavity loop. We demonstrate 50 nm wide soliton combs induced with average powers more than one order of magnitude lower than those typically used in state-of-the-art soliton micro-combs [1]. Very importantly, in stark contrast to temporal cavity-solitons based on passive Lugiato-Lefever systems, our bright laser cavity solitons are background-free, and we achieve a mode-efficiency [4] above 75%, compared to typical 1% - 5% for bright solitons realised with standard approaches. Furthermore, we can tune the repetition-rate to well over a megahertz with no-active control.
关键词： Lugiato-Lefever equation,optical frequency combs,micro-combs,micro-resonators,laser cavity-solitons
更新于2025-09-16 10:30:52
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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) - Quadratic Solitons and their Interaction with Dispersive Waves in Lithium Niobate Nano-Waveguides
摘要： Lithium Niobate (LN) nano-waveguides combine the high nonlinearity and broadband transparency of LN with the sensitive tunability of geometric group velocity dispersion (GVD) and the strong field enhancement of subwavelength waveguides. Together these properties make the newly emerging LN nano-waveguides a compelling candidate for research into dynamics of quadratic temporal solitons, and frequency conversion processes driven by solitons interacting with dispersive waves. Emission of resonant radiation (RR) by temporal solitons due to cubic nonlinearity is known to be one of the key mechanism behind supercontinuum generation. Recent research into cubic solitons interacting with quadratic nonlinearities has found new mechanisms for tunable RR. In this work we analyse theoretically bright temporal quadratic solitons in LN nano-waveguides. Quadratic solitons consist of two co-propagating pulses at fundamental harmonic (FH) and second harmonic (SH) frequencies. The interaction between these two pulses mediated by a nonlinear material allows for the self-phase modulation crucial for soliton formation. Using the slowly varying envelope approximation the normalised fields of the FH, and SH, are described by the coupled nonlinear equations. Structures in which both harmonics experience the same sign of group velocity dispersion (GVD) are predicted to support quadratic solitons. Sub-picosecond solitons with peak powers below 100W can be excited in LN nano-waveguides. We analyse different regimes of RR emission due to non-constant GVD in FH and SH, as well as three wave mixing (TWM) radiation driven by soliton interaction with dispersive waves. Our simulations show RR in agreement with our theoretical predictions. These results suggest the possibility of temporal quadratic soliton excitation and novel mechanisms for RR relevant to frequency conversion and supercontinuum generation in LN nano-waveguides.
关键词： dispersive waves,frequency conversion,resonant radiation,nano-waveguides,supercontinuum generation,Lithium Niobate,quadratic solitons
更新于2025-09-16 10:30:52
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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) - Self-Written Y-Junctions using Spatial Solitons
摘要： The self-focusing and the formation of spatial solitons attracted a great deal of attention since the early days of nonlinear optics. Essentially a high-power beam changes the refractive index, writing a waveguide capable to con?ne the beam itself. Accordingly, spatial solitons behave like optical waveguides for beams at different wavelength and low power, thus enabling the generation of integrated optical devices written by the light itself. Several all-optical devices have been demonstrated based on this principle, with particular attention devoted in the last two decades to nematic liquid crystals (NLCs) due to their huge nonlinear response. The main nonlinear mechanism in NLC for CW excitations is reorientational, that is, the extraordinary (e-) wave rotates the optical axis of the material, providing a focusing effect. Nonetheless, NLCs are also subject to a strong thermo-optical effect, typically yielding a defocusing effect for the e-wave. Here we demonstrate the excitation of couples of solitons with a single-humped beam caused by the interaction between reorientational and thermal nonlinearity.
关键词： thermal nonlinearity,nematic liquid crystals,reorientational nonlinearity,spatial solitons,nonlinear optics
更新于2025-09-16 10:30:52
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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) - Switching Dynamics of Dark Solitons in Kerr Microresonators
摘要： Dissipative Kerr solitons (DKS) are localized structures in optical resonators that arise from a double balance between dispersion and Kerr effect, and linear loss and parametric gain [1]. The periodic nature of DKS corresponds to frequency combs. DKS can be generated in high-Q microresonators for diverse applications, from coherent communications to precision frequency synthesis [1]. Most studies of DKS have focused on microresonator cavities operating in the anomalous dispersion regime, where the waveforms correspond to bright soliton pulses. Coherent microresonator combs can also be formed in the normal dispersion regime [2]. The time-domain waveform corresponds to a localized dark-pulse structure, interpreted as two interlocked switching waves connecting the two branches of the bi-stability curve in continuous-wave-pumped Kerr resonators [2,3]. Each switching wave connects the two branches following an oscillating behavior. These type of Kerr combs are relevant for practical applications because they display unusually high power-conversion efficiency [4,5], but their physical dynamics remain largely unexplored. Here, we report the discovery of deterministic switching of dark pulse Kerr combs, where the number of oscillations that appear between the switching waves can be either increased or decreased one at a time. The switching dynamics observed here have intriguing similarities to the switching behavior of bright temporal solitons in anomalous dispersion microresonators [6], and they indicate that dark pulse Kerr combs arise as a complex interplay of dark solitons circulating in the cavity.
关键词： microresonators,switching dynamics,dark pulse Kerr combs,Dissipative Kerr solitons
更新于2025-09-16 10:30:52
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Bright-dark solitons for a coupled nonlinear Schr?dinger system with variable coefficients in an inhomogeneous optical fiber
摘要： Optical fiber communication becomes one of the main pillars of modern communication. In this paper, we study a coupled nonlinear schr¨odinger system with variable coefficients, which can describe the simultaneous propagation of the M-field components in an inhomogeneous optical fiber, where M is a positive integer. When M=2, the N-bright-dark soliton solutions in terms of the Grammian can be obtained via the Kadomtsev-Petviashvili hierarchy reduction, where N is a positive integer. With the asymptotic analysis and graphic analysis, we find that the amplitudes of one-bright-dark solitons and the background in the dark components exhibit the periodic oscillations. Without the amplification/absorption effect, elastic interaction between the two-bright-dark solitons which keep both the amplitudes and the wave backgrounds invariant is demonstrated. Particularly, we find inelastic interaction between the two-bright-dark solitons, which possess the V-shape profiles in the zero background components and the Y-shape profiles in the periodic oscillating background components. The bound-state soliton under that inelastic condition is also shown. Besides, we present the bound-state bright-dark solitons with varying amplitudes. Furthermore, the analysis of the N-bright-dark soliton solutions are extended to those with M>2, and as an example, inelastic interaction of the solitons with the case of M=4 is presented.
关键词： Kadomtsev-Petviashvili hierarchy reduction,bright-dark solitons,Coupled nonlinear Schr¨odinger system with variable coefficients,an inhomogeneous optical fiber
更新于2025-09-16 10:30:52
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Phase separation of vector solitons in spin-orbit-coupled spin-1 condensates
摘要： We study the phase separation in three-component bright vector solitons in a quasi-one-dimensional spin-orbit-coupled hyperfine spin F = 1 ferromagnetic Bose-Einstein condensate upon an increase of the strength of spin-orbit (SO) coupling px(cid:2)z above a critical value, where px is the linear momentum and (cid:2)z is the z component of the spin-1 matrix. The bright vector solitons are demonstrated to be mobile and dynamically stable. The collision between two such vector solitons is found to be elastic at all velocities with the conservation of density of each vector soliton. The two colliding vector solitons repel at small separation and at very small colliding velocity, they come close and bounce back with the same velocity without ever encountering each other. This repulsion produced by SO coupling is responsible for the phase separation in a vector soliton for large strengths of SO coupling. The collision dynamics is found to be completely insensitive to the relative phase of the colliding solitons. However, in the absence of SO coupling, at very small velocity, the two colliding vector solitons attract each other and form a vector soliton molecule and the collision dynamics is sensitive to the relative phase as in scalar solitons. The present investigation is carried out through a numerical solution and an analytic variational approximation of the underlying mean-field Gross-Pitaevskii equation.
关键词： Bose-Einstein condensate,spin-orbit coupling,collision dynamics,vector solitons,phase separation
更新于2025-09-16 10:30:52
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Dark two-soliton solutions for nonlinear Schr?dinger equations in inhomogeneous optical fibers
摘要： In this paper, the variable coefficient nonlinear Schr¨odinger equation is investigated analytically. With the bilinear method, the bilinear forms and analytic soliton solutions are obtained. Based on the obtained analytic solutions, the effect of free parameters on the control of soliton transmission is studied. Influences of second-order and third-order dispersion coefficients on dark solitons are discussed. Results in this paper would be of great significance in the generation of dark solitons.
关键词： Bilinear method,Nonlinear Schr¨odinger equation,Partial differential equation,Solitons
更新于2025-09-16 10:30:52
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Breathers, multi-peak solitons, breather-to-soliton transitions and modulation instability of the variable-coefficient fourth-order nonlinear Schr?dinger system for an inhomogeneous optical fiber
摘要： Optical fiber communication system is one of the core supporting systems of the modern internet age. In this paper, under investigation is a variable-coefficient fourth-order nonlinear Schr?dinger system, which describes the simultaneous propagation of the optical pulses in an inhomogeneous optical fiber. The first-order breathers are constructed. Breathers are converted into several types of the nonlinear waves, i.e., multi-peak solitons, antidark solitons, periodic waves and W-shaped solitons, under the transition condition. With the decrease of |λr + a2|, the peak number of a multi-peak soliton increases, where λr represents the real part of the spectral parameter and a is a real constant. Peak number reaches the maximum since the multi-peak soliton is transformed into a set of the periodic waves with λr + a2 = 0. Widths and velocities of the multi-peak solitons are related to the group velocity dispersion and fourth-order dispersion coefficients. We find that the condition of baseband modulational instability coincides with the transition condition when we use the rogue-wave eigenvalues, i.e., the transition between the rogue waves and multi-peak solitons can occur in the baseband modulational instability.
关键词： Inhomogeneous optical fiber,Breathers,Multi-peak solitons,Modulation instability,Variable-coefficient fourth-order nonlinear Schr?dinger system
更新于2025-09-16 10:30:52