Effect of synchronous modulation on the soliton optical phase

We show that soliton regeneration through synchronous modulation reduces both amplitude and optical phase noise in a squeezinglike fashion. However, control of optical phase noise is found not to be sufficient to permit error-free phase-shift-keyed soliton transmission, as confirmed by numerical simulations.     

Effect of gain media characteristics on the formation of soliton molecules in fiber laser

Erbium doped fiber and Er³⁺/Yb³⁺ codoped phosphate glass fiber are used as the laser media, respectively, to achieve self-started mode-locking based on nonlinear polarization rotation. It is found that the formation of the soliton molecule is the popular phenomenon in fiber laser. The laser media with high gain coefficient and short length is benefit of the formation of the soliton molecule at fundamental repetition rate and will generate evident soliton molecule pulse profile with strong accompanied structures. The achievement of soliton molecule owes to the partial operation of polarization filter effect in laser cavity due to the weak nonlinear polarization rotation in gain media with high gain coefficient and short length.     

Effect of pulse parameters on the passive layer formation on pulse plated Ni-Co alloys

From a chloride bath, Ni-Co alloys were pulse plated by varying the pulse parameters off-time and the peak current densities using a pulse generator that applies a square wave signal in order to examine the mechanism of the passive oxide layer formation on the deposited coatings in the frame of pulse parameters.Cyclic voltammetry and potential step measurements were carried out in order to characterise the electrochemical behaviour on the Ni-Co coatings at a selected electrode potential in an alkaline solution. Calculation of the oxide layer formation was evaluated from the total charge, determined by recorded current-time transients and from ICP-analysis of the samples. The most protective and compact oxide was formed on the sample that was deposited at low current densities and at high off-time.     

Asymmetric W-shaped and M-shaped soliton pulse generated from a weak modulation in an exponential dispersion decreasing fiber

We study localized waves on continuous wave background in an exponential dispersion decreasing fiber with two orthogonal polarization states. We demonstrate that asymmetric W-shaped and M-shaped soliton pulse can be generated from a weak modulation on continuous wave background. The numerical simulation results indicate that the generated asymmetric soliton pulses are robust against small noise or perturbation. In particular, the asymmetric degree of the asymmetric soliton pulse can be effectively controlled by changing the relative frequency of the two components. This character can be used to generate other nonlinear localized waves, such as dark–antidark and antidark–dark soliton pulse pair, symmetric W-shaped and M-shaped soliton pulse. Furthermore, we find that the asymmetric soliton pulse possesses an asymmetric discontinuous spectrum.     

Mechanism of pulse shaping in femtosecond lasers based on the high-order soliton

The mechanism of pulse shaping in Kerr-lens mode-locking Ti : sapphire lasers is investigated. Considering the balanced interaction between self-phase modulation, introduced by Kerr effect in Ti : sapphire, and group-velocity dispersion provided by prism-pair, pulse-splitting reflected in the intensity autocorrelation trace and pulse-compression display that the pulses outputting from different positions in laser cavity have different durations. We have concluded that the solitonlike pulse shaping that results from the competition between intracavity self-phase modulation within the Ti : S and negative group-velocity dispersion play dominant role in pulse evolution in Kerr-lens mode-locking lasers.     

The influence of perturbations on the shape of a sine-Gordon soliton

The deformation of a perturbed sine-Gordon soliton is calculated in first-order perturbation theory. Some examples of physical interest are considered.     

Effect of the field of a nonlinear electromagnetic wave on the shape of a soliton in a semiconductor superlattice

The effect of the electric component of the field of a high-frequency (HF) nonlinear electromagnetic (EM) wave on the propagation of a solitary EM wave (soliton) in a quantum semiconductor superlattice is studied. It is noted that in the collisionless approximation, the solution of the modified sine-Gordon equation corresponding to the amplification of an EM pulse that, with allowance made for interminiband electron transitions, transforms into a dissipative soliton is possible. The effect of electron collisions with irregularities of the crystal lattice on the soliton dynamics under the action of the field of a HF nonlinear wave is considered. The condition for an increase in the traveling time of the solitary wave is found.     

Effect of driving voltage pulse shape on the luminance of thin-film electroluminescent devices

The dependence of the average luminance on the parameters of the metal-insulator-semiconductor-insulator-metal structures in thin-film electroluminescent devices (TFELDs) and on the excitation conditions is found by solving kinetic equations for the variation in the concentration of excited emission centers in the phosphor layer of TFELDs for different driving voltage pulse shapes (triangular, trapezoidal, sinusoidal, and rectangular with an exponential leading edge). It is shown that for equal amplitudes and pulse repetition rates of a sign-changing symmetric voltage, the average luminance and luminous efficacy of TFELDs increase as the rate of rise of the voltage is increased for different driving voltage pulse shapes in the following sequence: triangular, sinusoidal, trapezoidal, rectangular. The calculations are confirmed by experiment. Zh. Tekh. Fiz. 69, 64–69 (February 1999)     

在反常色散区艾里脉冲与光孤子相互作用规律的研究

本文采用分步傅里叶法,研究了在反常色散区孤子和艾里脉冲相互作用的规律,并且对相互作用后的孤子和艾里脉冲各自的强度、时域和时移进行了MATLAB仿真.通过仿真发现光孤子和艾里脉冲在光纤中相互重叠时,交叉相位调制(XPM)就会建立并且这种调制会影响孤子和艾里脉冲的性质.在相互作用过程中,孤子的形状保持不变,但是受到艾里脉冲自加速特性的影响孤子会发生偏移.艾里脉冲受XPM的影响会转化为孤子,传播方向也会发生偏移.可见,XPM使得艾里脉冲和孤子各自的性质都相互影响着对方.艾里脉冲和孤子的时域也会受到XPM的影响,使得原本不相同的脉冲形状都转变为含有一个主峰和一个次峰的相似结构,并且主峰和次峰的位置和脉冲宽度也大致相同,这也是艾里脉冲能够转换为孤子的一个依据.另外本文还模拟了不同输入强度r下的孤子和艾里脉冲的变化情况,模拟发现不管是艾里脉冲还是孤子时移都随着输入强度r的增大而增大,并且它们的变化趋势都是一样的,同时模拟还发现在相同的的r值下,时移也会随着a值的增大而增大.     

Effect of line coding on jitter and initial laser phase on Q value in soliton transmission

In this paper we described how different line coding techniques vary with values of jitter in soliton transmission system. Then the idea of this soliton transmission system is applied for multiuser structure and effects of initial line phase spacing are examined.     

Effect of parametric modulation on pattern formation in reaction diffusion systems

Reaction diffusion systems can exhibite both spatial and temporal patterns. We show that the effect of spatial variation of the removal rate can have significant effect on the stability boundaries. In particular there can be a case of parametric resonance. Received 11 March 1998     

双光子吸收效应对孤子和孤子对传输的影响

用分步傅立叶变换法求解含双光子吸收效应的光孤子NLS方程,研究了双光子吸收效应对一阶孤子和孤子对传输的影响,发现双光子吸收效应除对孤子产生等效损耗外,还影响了孤子对在传输中的相互作用。在特定的双光子吸收系数条件下双光子吸收效应可以使孤子对平行地向前传输。     

Effect of the shape of the light pulse on the optical breakdown threshold of transparent dielectrics

The problem concerning the nonsteady heating by a light pulse of arbitrary shape, of an insulated metallic microparticle located in a transparent dielectric, is solved. The effect of the shape of the heating pulse on the nature of heating up of the inclusion is investigated. The results of the paper can be used for the experimental verification of the heat-conductivity theory of breakdown of solid transparent dielectrics.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 77–81, February, 1979.In conclusion, the authors thank V. A. Gorshkov for assistance in carrying out the calculations.     

Effect of dark soliton on the spectral evolution of bright soliton in a silicon-on-insulator waveguide

The spectral evolution of bright soliton in a silicon-on-insulator optical waveguide is numerically simulated using the split-step Fourier method. The power and input chirp of the dark soliton and the second-order dispersion are varied to investigate the effect of dark soliton on the spectrum of bright soliton. The simulations prove that the dark soliton modifies the spectral shape of the bright soliton. Further, the variation in the power of dark soliton affects the splitting of bright soliton. Furthermore, the chirped dark soliton can improve the spectral width and flatness. The variation in the dispersion of dark soliton modifies the phase matching of the bright soliton and the dispersive wave emission, thereby affecting the spectral evolution.     

Neutron-rich hypernuclei in the chiral soliton model

The binding energies of neutron-rich strangeness S = ?1 hypernuclei are estimated in the chiral soliton approach using the bound state rigid oscillator version of the SU(3) quantization model. Additional binding of strange hypernuclei in comparison with nonstrange neutron-rich nuclei takes place at not large values of atomic (baryon) numbers, A = B ?? ??10. This effect becomes stronger with increasing isospin of nuclides, and for the ??nuclear variant?? of the model with rescaled Skyrme constant e. Binding energies of _?? ⁸ He and recently discovered _?? ⁶ H satisfactorily agree with data. Hypernuclei _?? ⁷ H, _?? ⁹ He are predicted to be bound stronger in comparison with their nonstrange analogues ⁷H, ⁹He; hypernuclei _?? ¹⁰ Li, _?? ¹¹ LI, _?? ¹² Be, _?? ¹³ Be, etc. are bound stronger in the nuclear variant of the model.     

Effect of the third-order filter term on soliton interactions in soliton transmission systems with filters

The effect of the third-order filter term on soliton interactions in optical fibers with guiding filters is theoretically analyzed. We find that this term causes a significant difference to the interaction of solitons through filters among the regimes of without sliding, with up- and down-sliding frequencies of filters. It is shown that the interaction between solitons can be more effectively suppressed by up-sliding filters than that by down-sliding filters in the presence of the third-order filter term. Moreover, the third-order filter term is found to play a positive role in suppressing soliton interactions in the case of non-sliding.     

初始啁啾对飞秒脉冲在光子晶体光纤中超连续谱产生的影响

采用分步傅里叶方法模拟了初始啁啾对光子晶体光纤中超连续谱产生的影响.根据光纤长度，将光子晶体光纤中脉冲的演化分成初始展宽、剧烈展宽和饱和展宽三个阶段.通过讨论啁啾脉冲和无初始啁啾脉冲在各阶段演化的区别，发现啁啾只在初始展宽和剧烈展宽阶段对光谱有影响，当β₂C<0时啁啾有利于光谱的展宽，当β₂C>0时则刚好相反，在饱和展宽阶段啁啾不再对光谱产生影响.要想利用啁啾脉冲来获得较宽的光谱，必须选择合适的光纤长度，使输出的脉冲处于剧烈展宽阶段.这为利用啁啾脉冲在光子晶体光 关键词： 超连续谱 光子晶体光纤 分步傅里叶法 啁啾     

Direct generation of a 10 GHz 816 fs pulse train from an erbium-fiber soliton laser with asynchronous phase modulation

By employing the technique of asynchronous mode locking, we have successfully demonstrated direct generation of stable 10 GHz 816 fs pulse trains with a supermode-suppression ratio >70 dB from a hybrid mode-locked Er-fiber laser. When the modulation frequency deviates from the cavity harmonic frequency by 15-40 kHz, stable femtosecond soliton pulses are formed. Our results demonstrate that asynchronous mode locking can act as an effective mechanism for achieving a shorter pulse width and for stabilizing high-repetition-rate pulse trains in soliton fiber lasers.