- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Soliton slow light for closed loop quantum systems
摘要： This paper describes the dynamics of solitonic pulse propagation in a closed loop quantum system comprised of five atomic energy levels. Although the propagation of an intense probe pulse suffers losses and broadening in linear regime, there exist specific conditions where the probe pulse is found to become robust during its propagation. We attribute this regime to the formation of an optical soliton with a slow group velocity because of the balance between the dispersion and Kerr optical nonlinearity. Results obtained are based on the theoretical model using the coupled Maxwell-Bloch equations for the nonlinear propagation.
关键词： Optical solitons,Kerr nonlinearity,Nonlinear pulse propagation,Closed-loop quantum system
更新于2025-09-23 15:23:52
-
Pulse delay and group velocity dispersion measurement in V-type electromagnetically induced transparency of hot <sup>85</sup>Rb atom
摘要： Pulse delay with the group velocity dispersion (GVD) characteristics was studied in the V-system configuration. The phase coherency between the pump and the probe laser beams was maintained. We studied the pulse delay and the GVD characteristics with the variation of the type electromagnetically induced transparency in the hyperfine levels of 85Rb atoms with a closed electromagnetically induced transparency of hot 85Rb atom. For a better understanding of the experimental results, we have derived an analytical solution for the three level V-type system. The theoretical plots of the delay and the group velocity dispersion show the same characteristics as we observed in the experiment. This analytical approach can be further generalized for the higher level schemes to calculate different quantities such as susceptibility, group velocity delay or group velocity dispersion characteristics.
关键词： electromagnetically induced transparency,Coherent optical effects,Pulse propagation and temporal solitons
更新于2025-09-23 15:21:21
-
Analytic Mode Normalization for the Kerr Nonlinearity Parameter: Prediction of Nonlinear Gain for Leaky Modes
摘要： Based on the resonant-state expansion with analytic mode normalization, we derive a general master equation for the nonlinear pulse propagation in waveguide geometries that is valid for bound and leaky modes. In the single-mode approximation, this equation transforms into the well-known nonlinear Schr?dinger equation with a closed expression for the Kerr nonlinearity parameter. The expression for the Kerr nonlinearity parameter can be calculated on the minimal spatial domain that spans only across the regions of spatial inhomogeneities. It agrees with previous vectorial formulations for bound modes, while for leaky modes the Kerr nonlinearity parameter turns out to be a complex number with the imaginary part providing either nonlinear loss or even gain for the overall attenuating pulses. This nonlinear gain results in more intense pulse compression and stronger spectral broadening, which is demonstrated here on the example of liquid-filled capillary-type fibers.
关键词： resonant-state expansion,Kerr nonlinearity,leaky modes,nonlinear pulse propagation,waveguide geometries
更新于2025-09-23 15:21:21
-
A perturbative approach to self-phase modulation and self-steepening of short laser pulses propagating in nonlinear media
摘要： The solution of the wave equation in the envelope approximation with temporal corrections for a laser pulse propagating in a medium where the Kerr effect, field ionization, and associated absorption take place, is obtained through a first order perturbative approach. Dispersion is, however, neglected to decouple the equations for the amplitude and the phase. The closed-form expressions so obtained clarify the influence of the various terms of the equation on the laser amplitude and on the frequency generation as a function of the retarded time. Furthermore, they allow extracting scaling parameters which size the nonlinear effects. The results are illustrated quantitatively in the case of a femtosecond pulse focused in the air with typical parameters.
关键词： perturbative approach,self-phase modulation,self-steepening,short laser pulse propagation
更新于2025-09-23 15:21:01
-
Nonlinear Optics - Novel Results in Theory and Applications || Polarization Properties of the Solitons Generated in the Process of Pulse Breakup in Twisted Fiber Pumped by ns Pulses
摘要： Common optical fibers are randomly birefringent, and solitons formatting and traveling in them are randomly polarized. However, it is desirable to have solitons with a well-defined polarization. With pump relatively long pulses, the nonlinear effects of modulation instability (MI) and stimulated Raman scattering (SRS) are dominant at the initial stage of the process of supercontinuum (SC) generation; modulation instability results in pulse breakup and formation of short pulses that evolve finally to a bunch of solitons and dispersive waves. We do the research of the polarization of solitons formed by the pulse breakup process by the effect of modulation instability with pump pulses of nanoseconds in standard fiber (SMF-28) with circular birefringence introduced by fiber twist, and the twisted fiber mitigates the random linear birefringence. In this work, we found that polarization ellipticity of solitons is distributed randomly; nevertheless, the average polarization ellipticity is closer to the circular than the polarization ellipticity of the input pulse. In the experimental setup. 200 m of SMF-28 fiber twisted by 6 turns/m was used. We used 1 ns pulse to pump the fiber. The results showed that at circular polarization of the input pulse solitons at the fiber output have polarizations close to the circular, while in the fiber without twist, the soliton polarization was random.
关键词： pulse propagation and temporal solitons,birefringence and polarization,fiber optic,stimulated Raman scattering,nonlinear optics
更新于2025-09-19 17:13:59
-
Numerical approaches for solving the nonlinear Schr??dinger equation in the nonlinear fiber optics formalism
摘要： This work presents a novel numerical stability analysis of a collection of pseudo-spectral methods, also known as split-step methods, for solving pulse propagation modelled by the nonlinear Schr¨odinger equation in the nonlinear ?ber optics formalism. In order to guarantee the convergence of di?erent pulse propagation dynamics, the numerical solutions of the pseudo-spectral methods (split-step Fourier method, symmetric split-step Fourier method, fourth order Runge-Kutta in the interaction picture method, and an optimization of split-step Fourier schemes for pulse propagation over long distances) are tested by the validation of the conservation laws that govern this system. The presented numerical results are an illustrative guide to consider in the selection of an appropriate numerical method in future investigations of a wide variety of propagation problems that involve the interplay of the linear and nonlinear contribution in the nonlinear Schr¨odinger equation, in order to reproduce accurately a speci?c phenomenology using this formalism.
关键词： nonlinear ?ber optics,Nonlinear Schr¨odinger equation,split-step methods,optical ?ber,optical pulse propagation
更新于2025-09-19 17:13:59
-
35 fs, all-polarization-maintaining MOPA laser system
摘要： We have experimentally observed ultrashort pulse in a simple, all-polarization-maintaining fiber, master oscillator and power amplifier laser. A semiconductor saturable mirror (SESAM) module is used as the mode locker. The ultrashort pulse exhibits perfect Gaussian spectrum without any fine structure. The 20 dB pulse spectral width is 28 nm, and the pulse duration directly output from the oscillator is 268.6 fs. Via a two-stage amplifier, the pulse spectrum is greatly broadened to 43 nm, and the pulse duration lengths to 0.9 ps. Moreover, after compression, a typical saddle-shaped spectrum appears and the spectral bandwidth broadens to 121 nm; the pulse duration is compressed to ~35 fs with a pulse peak power of 22.79 kW, which is high enough to stimulate a one-octave supercontinuum spectrum. Due to the polarization-maintaining structure and high reliability of SESAM, the whole system exhibits strong environmental stability. Experimental observation reveals that such a fiber laser with a very simple structure exhibits excellent performance, and could be applied in the area of optical frequency comb.
关键词： ultrafast fiber lasers,pulse propagation and temporal solitons,pulse compression
更新于2025-09-16 10:30:52
-
A chaotic state in the transition from single- toward multiple pulse for soliton fiber lasers
摘要： High-order soliton in anomalous-dispersion ultrafast fiber lasers is rarely researched due to its intrinsic instability in dissipative systems. For the first time, we numerically demonstrate the ultrafast pulse in fiber lasers will deviate from the fundamental soliton under strong pulse energy before splitting into multiple pulses. High-order soliton effect results in the single-pulse splitting into the dual-pulse. Sustaining switching between the single- and dual-pulse induced by the high-order soliton evolution and cross-gain-modulation was observed and analyzed. The results offer significant and novel insights for the soliton shaping dynamics and instability in anomalous-dispersion fiber lasers.
关键词： Mode-locked lasers,nonlinear fiber optics,temporal soliton and pulse propagation
更新于2025-09-16 10:30:52
-
Nonlinear Fiber Optics || Pulse propagation in fibers
摘要： For an understanding of the nonlinear phenomena in optical ?bers, it is necessary to consider the theory of electromagnetic wave propagation in dispersive nonlinear media. The objective of this chapter is to obtain a basic equation that governs propagation of optical pulses in single-mode ?bers. Section 2.1 introduces Maxwell’s equations and important concepts such as the linear and nonlinear parts of the induced polarization and the frequency-dependent dielectric constant. The concept of ?ber modes is introduced in Section 2.2 where the single-mode condition is also discussed. Section 2.3 considers the theory of pulse propagation in nonlinear dispersive media in the slowly varying envelope approximation with the assumption that the spectral width of the pulse is much smaller than the frequency of the incident radiation. The numerical methods used to solve the resulting propagation equation are discussed in Section 2.4.
关键词： electromagnetic wave propagation,dispersive nonlinear media,numerical methods,nonlinear phenomena,optical fibers,single-mode fibers,fiber modes,pulse propagation,dielectric constant,induced polarization,Maxwell’s equations
更新于2025-09-12 10:27:22
-
Harmonic Mode-Locking in Bidirectional Domain-Wall Soliton Fiber Lasers
摘要： We report on the first experimental observation of passively harmonic mode-locking (HML) in a bidirectional domain-wall dark-soliton fiber laser. The domain-wall solitons (DWSs) are characterized, in which, the strong coupling between the two directions takes great responsibility for the generation. By appropriately altering the polarization state in the cavity, the stable fundamental domain-wall solitons and HML states could be obtained and switched with increasing the pump power. In our experiment, the repetition rate can be tunable from the fundamental mode locking of 2.96 MHz up to eighth-order HML of 23.68 MHz when the pump power is increased from 120 to 542.5 mW. Importantly, this HML operation of dark-pulse DWSs confirms that the DWSs are the intrinsic feature of the mode-locked lasers, as well as the conventional bright solitons. This work could provide a new perspective to the understanding of the formation and transformation of dark solitons, which may also find great potential applications in fiber sensing and future optical communication systems.
关键词： lasers and laser optics,mode-locked lasers,ultrafast photonics,pulse propagation and temporal solitons
更新于2025-09-12 10:27:22