- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Three-component coupled nonlinear Schr??dinger equation: Optical soliton and modulation instability analysis
摘要： This study successfully extracts the combined dark-bright and singular optical solitons to the three-component nonlinear Schr¨odinger equation by using the extended sinh-Gordon equation expansion method. The modulation instability analysis of the governing model is also presented. By using suitable values of the parameters, the 2-, 3-dimensional, and contour graphs to the reported results and the gain spectrum for the modulation instability analysis are plotted.
关键词： Optical soliton,Modulation Instability,Three-component NLSE
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) - Plug-and-Play Generation and Manipulation of Squeezing on Chip
摘要： We propose a novel graphic method to enable the analysis of the field-effect transistor (FET) threshold voltage variation (cid:2)Vth due to random telegraph signals in a percolative channel. First, through technology computer-aided design simulation with no percolation, both a minimum (cid:2)Vth and a critical curve in a mloc ? σloc plot are produced. The former constitutes a statistical distribution far away from the conventional log-normal one. In the latter, mloc and σloc are the mean and the standard deviation, respectively, of a well-known normal variable in Mueller–Schulz’s percolation theory. The critical mloc ? σloc curve divides the plot into the allowed region and the forbidden region and will go down with increasing gate size. Then, (cid:2)Vth contours in the allowed region are graphically created. While applying to existing experimental (cid:2)Vth statistical distributions of SiON- and high-k metal gate (HKMG)-scaled FETs, resulting paired mloc and σloc at high (cid:2)Vth remain intact, regardless of gate size or gate stack type. This means that the underlying percolation patterns resemble each other, due to the same manufacturing process used. However, if these paired mloc and σloc fall in the forbidden region, it is the critical mloc ? σloc curve dominating. Application to bias and temperature instability statistical data in literature is straightforwardly well done.
关键词： percolation,technology computer-aided design (TCAD),Bias and temperature instability (BTI),trap,random telegraph signals (RTSs),field-effect transistors (FETs)
更新于2025-09-16 10:30:52
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Numerical study of Riskena??Nummedala??Grahama??Haken instability in mid-infrared Fabrya??P??rot quantum cascade lasers
摘要： We review our recent theoretical studies on multimode instabilities in Fabry–Pérot cavity mid-infrared quantum cascade lasers (QCLs) caused by parametric excitation of Rabi flopping oscillations. Numerical simulations are based on the semiclassical traveling wave Maxwell–Bloch equations. QCLs with a few mm cavity without an absorber exhibit intermittent RNGH self-pulsations, while regular self-pulsations are possible in short-cavity QCLs, with the cavity length of 100 μm or smaller. However, the second threshold in short-cavity QCLs is significantly increased compared to the values for a few mm long devices. We provide here a new insight on RNGH instability via bifurcation analysis of the output waveform and studies of the recurrence period density entropy. We propose an interpretation of the broadening/narrowing of the optical spectrum of a QCL i.e. switching the RNGH instability on and off observed in experiment.
关键词： Quantum cascade laser,RNGH instability,Self-pulsations,Bifurcation diagram,Spatial hole burning
更新于2025-09-16 10:30:52
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Coarse Grained Simulation and Turbulent Mixing || Laser Driven Turbulence in High Energy Density Physics and Inertial Confinement Fusion Experiments
摘要： The mixing of initially separate materials in a turbulent ?ow by the small scales of turbulent motion is a critical and often poorly understood element of many research programs, such as inertial con?nement fusion (ICF), supernova implosions and explosions, and combustion, as well as many other applications in engineering, geophysics, and astrophysics. In typical contexts of interest, we are interested in achieving detailed understanding of interpenetration, hydrodynamical instabilities, and mixing arising from perturbations at the material interfaces, that is, driven by Rayleigh–Taylor (RT), Richtmyer–Meshkov (RM), and Kelvin–Helmholtz (KH) instabilities (buoyancy, shock, and shear induced instabilities, respectively). Laboratory observations typically provide only limited integrated measures of complex nonlinear three-dimensional physical processes, leaving many details and mechanisms unresolved. Carefully controlled computational experiments based on the numerical simulations play a crucial complementary role, providing insight into the underlying dynamics. Collaborative laboratory/computational studies are used to establish predictability of the models in conjunction with the development of frameworks for analysis, metrics for veri?cation and validation, and uncertainty quanti?cation.
关键词： Richtmyer–Meshkov instability,Rayleigh–Taylor instability,inertial con?nement fusion,turbulent mixing,high energy density physics,Kelvin–Helmholtz instability
更新于2025-09-12 10:27:22
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The Physics of the one-dimensional nonlinear Schr?dinger equation in fiber optics: rogue waves, modulation instability and self-focusing phenomena
摘要： We review the different dynamical mechanisms leading to the emergence of coherent structures in physical systems described by the integrable one-dimensional nonlinear Schr?dinger equation (1DNLSE) in the focusing regime. In this context, localized and coherent structures are very often associated to rogue wave events. We focus on one-dimensional optical experiments and in particular on (single mode) optical fibers experiments. In the focusing regime of 1DNLSE, the so-called modulation instability (MI), arising from nonlocal perturbation of the plane waves, is the most common phenomenon. Alongside the standard MI, other mechanisms are responsible for the emergence of rogue waves. We classify the different scenarios by considering those induced by small perturbations of unstable stationary state (the plane waves) and the ones arising from the self-focusing of large pulses without any perturbation. In the former case, the perturbations can be local, global, random or deterministic. In the latter case, the self-focusing dynamics can be observed both with isolated pulses or with large initial fluctuations of the optical power. We review the dynamics of emergence of localized structures in all these different scenarios.
关键词： modulation instability,nonlinear Schr?dinger equation,self-focusing phenomena,rogue waves,fiber optics
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) - Pump-Power-Noise Influence on Mode Instabilities in High-Power Fiber Laser Systems
摘要： Transverse mode instability (TMI) is still the most limiting effect for the further average-power scaling of fiber lasers and amplifiers with excellent beam quality. For the modal energy transfer to happen, a phase shift between the thermally-induced refractive index grating and the modal interference pattern in the fiber is essential. In former experimental and theoretical studies it has been shown that such a phase shift can be induced by changes of the pump power. Thus, the investigation of the influence of pump-power noise on the TMI threshold is of high relevance since this noise could act as the main trigger for TMI. To experimentally examine this behavior, white noise with a bandwidth of 2 kHz was generated and transferred via an arbitrary waveform generator to the pump-diode driver. The connected laser diode pumped a 1.1 m long Large Pitch Fiber (LPF) with an active core of ~65 μm from the counter-propagating direction. The TMI threshold of the free-running system was measured according to [5] to be 256 W. The above mentioned frequency range of the white noise was chosen because it was found that only frequency components below 2 kHz have an significant impact on the TMI threshold of the particular system. To investigate the influence of the pump-power noise on the TMI threshold we varied the amplitude of the generated pump noise and measured the latter by sending a partial reflex of the pump beam onto a photodiode. The relative intensity noise (RIN) serves as a measure of the pump-noise amplitude and was calculated by integrating the power spectral density of the measured noise trace. Afterwards, the TMI threshold was determined according to [5] for different RINs, i.e., pump-noise amplitudes. The results are illustrated in Fig. 1. As can be seen, the fiber laser system started with a TMI threshold of 256 W (no artificial noise, RIN = 0.209 %, close to the measured dark noise) and could be decreased by almost a factor of three to 89 W (RIN = 2.927 %) by steadily increasing the pump-noise amplitude. Thus, the experiments have revealed that pump-power noise significantly influences the TMI threshold of fiber laser systems and, thus, likely acts as the main trigger for TMI. The nonlinear decrease of the TMI threshold with increasing pump-power noise (i.e., RIN), as shown in Fig. 1, can be explained with the nonlinearity with which the strength of the energy transfer grows with increasing average power. This correlation together with the current investigations on seed-power noise will also be discussed at the conference. From the experiments it can be concluded that developing low-noise pump sources and drivers could increase the TMI threshold of fiber lasers and amplifiers and, thus, it has the potential to enable a further average-power scaling of these systems with excellent beam quality.
关键词： Transverse mode instability,pump-power noise,fiber lasers,TMI,RIN
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Optical solitons
摘要： A fascinating manifestation of the fiber nonlinearity occurs through optical solitons, formed as a result of the interplay between the dispersive and nonlinear effects. The word soliton refers to special kinds of wave packets that can propagate undistorted over long distances. Solitons have been discovered in many branches of physics. This chapter focuses on pulse propagation inside optical fibers in the regime in which both the group-velocity dispersion (GVD) and self-phase modulation (SPM) are equally important and must be considered simultaneously. It is organized as follows. Section 5.1 considers the phenomenon of modulation instability and shows that propagation of a continuous-wave (CW) beam inside optical fibers is inherently unstable and may convert the CW beam into pulse train under appropriate conditions. The inverse-scattering method is discussed in Section 5.2 together with the soliton solutions. The properties of the fundamental and higher-order solitons are also discussed in this section. Section 5.3 is devoted to other kinds of solitons, with emphasis on dark solitons. Section 5.4 considers the effects of external perturbations on solitons. Perturbations discussed include fiber losses, amplification of solitons, and noise introduced by optical amplifiers. Higher-order nonlinear effects such as self-steepening and intrapulse Raman scattering are the focus of Sections 5.5 and 5.6.
关键词： modulation instability,optical amplifiers,dark solitons,intrapulse Raman scattering,inverse-scattering method,self-steepening,group-velocity dispersion,fiber nonlinearity,self-phase modulation,fiber losses,optical solitons
更新于2025-09-12 10:27:22
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Ionization-field instability in the laser-induced breakdown of nanoporous dielectric
摘要： The theory of ionization-?eld instability in a continuous homogeneous medium is generalized to the heterogeneous nanoporous one with the purpose to clear and analyze the mechanism of nanograting formation during the optical breakdown process in a transparent dielectric (fused silica) containing multiple small inclusions (nanobubbles) with a lowered ionization threshold. Based on the Maxwell Garnett approximation extended to include the size effect caused by the ?nite ratio of the bubble sizes to the scale of unstable perturbations, we have obtained the equation system describing the spatiotemporal evolution of the plasma density, average ?eld, and effective dielectric permittivity and have derived the characteristic equation connecting the temporal growth rate of these perturbations with their spatial period. Analysis of the roots of this equation shows that the unstable periodic perturbation structure having the maximal growth rate is close in character to the nanogratings observed experimentally (modulation in the direction of the pump wave polarization with the period approximately equal to the half-wavelength in the host material).
关键词： laser-induced breakdown,nanograting formation,nanoporous dielectric,Maxwell Garnett approximation,ionization-field instability
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Multimode fibers
摘要： Multimode fibers were first used for nonlinear optics during the 1970s because most optical fibers available at that time supported multiple modes. The situation changed in the 1980s when single-mode fibers were commercialized in view of their telecommunication applications. The interest in multimode fibers re-surfaced after 2005, partly motivated by their use for space-division multiplexing in optical communication systems. As a byproduct of this interest, the nonlinear effects in multimode fibers have been studied extensively since 2010. This chapter covers recent advances in a systematic fashion. Three types of multimode fibers are introduced in Section 14.1, where we also discuss modes supported by them. Section 14.2 extends theory of Section 2.3 to obtain a set of coupled nonlinear equations for various fiber modes. These equations are used in Sections 14.3 to discuss modulation instability and soliton formation in multimode fibers. The focus of Section 14.4 is on the intermodal nonlinear effects that transfer energy among the modes. The spatio-temporal effects are discussed in Section 14.5 with emphasis on spatial beam cleanup and supercontinuum generation through multimode fibers. Section 14.6 is devoted to the nonlinear phenomena in multicore fibers.
关键词： modulation instability,spatio-temporal effects,spatial beam cleanup,soliton formation,multimode fibers,multicore fibers,supercontinuum generation,nonlinear optics,space-division multiplexing,intermodal nonlinear effects
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Cross-phase modulation
摘要： So far we have focused on optical pulses whose spectrum is centered at a single wavelength. When two or more pulses, launched at different wavelengths, propagate simultaneously inside a fiber, they interact with each other through the fiber’s nonlinearity. In general, such an interaction can generate new waves under appropriate conditions through a variety of nonlinear phenomena such as stimulated Raman or Brillouin scattering and four-wave mixing; these are discussed in Chapters 8 to 10. The nonlinearity can also couple two optical fields through cross-phase modulation (XPM), without inducing any energy transfer between them [1]. The XPM phenomenon is discussed in this chapter. A set of two coupled nonlinear Schr?dinger (NLS) equations is derived in Section 7.1, assuming that each wave maintains its state of polarization. These equations are used in Section 7.2 to discuss how the XPM affects the phenomenon of modulation instability. Section 7.3 focuses on the soliton pairs whose members support each other through their XPM-mediated nonlinear interaction. The effects of XPM on the shape and the spectrum of ultrashort pulses are described in Section 7.4 by solving the coupled NLS equations. Several applications of XPM are discussed in Section 7.5. A vector theory of XPM is developed in Section 7.6 to account for the polarization effects. In Section 7.7 we extend this theory to the case of birefringent fibers. The case of two counterpropagating waves is discussed in Section 7.8.
关键词： modulation instability,soliton pairs,counterpropagating waves,birefringent fibers,polarization effects,ultrashort pulses,nonlinear Schr?dinger equations,cross-phase modulation
更新于2025-09-12 10:27:22