Carrier-envelope phase of ultrashort pulsed Laguerre-Gaussian beam

The carrier-envelope phase of the ultrashort pulsed Laguerre-Gaussian beam is studied.The order of Laguerre function affects seriously the variations of the carrier-envelope phase with the propagation distance increasing.The beam waist also affects the carrier-envelope phase in a few Rayleigh distances.The variation of the carrier-envelope phase is larger on the axis than on the beam periphery in propagation.     

小波变换提取放大超短脉冲载波-包络相位的研究

提出了一种新的超短放大脉冲的载波-包络相位还原方法,应用小波变换从超短放大脉冲的光谱拍频干涉中直接提取载波-包络相位. 消除了传统的Fourier变换方法不同宽度的滤波窗口引入不同程度的相位噪声而产生不确定性的影响,得到了更精确的载波-包络相位信息,对于近单周期超短脉冲特性测量具有重要意义. 关键词： 超短脉冲 载波-包络相位 相位还原 小波变换     

Radiating and nonradiating dispersion-managed solitons

Using spectral analysis, we present the salient features of the radiating behavior of optical solitons in dispersion-managed fiber systems. Depending on the map strength of the system, we find a rich variety of dynamic states that includes weak, moderate, and strong radiation states. We establish the existence of a critical map strength at which a Gaussian-shaped light pulse with a large initial dressing undergoes highly stable nonradiative propagation over transoceanic distances.     

Carrier-envelope phase dependence of few-cycle ultrashort laser pulse propagation in a polar molecule medium

We theoretically investigate carrier-envelope phase dependence of few-cycle ultrashort laser pulse propagation in a polar molecule medium. Our results show that a soliton pulse can be generated during the two-photon resonant propagation of few-cycle pulse in the polar molecule medium. Moreover, the main features of the soliton pulse, such as pulse duration and intensity, depend crucially on the carrier-envelope phase of the incident pulse, which could be utilized to determine the carrier-envelope phase of a few-cycle ultrashort laser pulse from a mode-locked oscillator.     

Stochastic perturbation of dispersion-managed optical solitons

The stochastic perturbation of dispersion-managed optical solitons is studied in this paper, in addition to deterministic preturbation terms, by the aid of soliton perturbation theory. The super-Gaussian pulses are considered and the corresponding Langevin equations are derived and analyzed. It is shown that in presence of the perturbation terms, the soliton propagates down the fiber with a fixed mean energy.OCIS Codes: 060.2310; 060.4510; 060.5530; 190.4370     

Carrier-envelope phase dependence of the duration of generated solitons for few-cycle rectangular laser pulses propagation

We investigate the nonlinear propagation of few-cycle rectangular laser pulses on resonant intersubband transitions in semiconductor quantum wells using an iterative predictor–corrector finite-difference time-domain method. An initial 2π rectangular pulse will split into Sommerfeld–Brillouin precursors and a self-induced transparency soliton during the course of propagation. The duration of generated soliton depends on the carrier-envelope phase of the incident pulse. In our case, not only the near-resonant frequency components but also the low frequency components could contribute to the generation of the soliton pulse when the condition of multi-photon resonance is satisfied. The phase-sensitive property of the solitons results from the phase-dependent distribution of high and low frequency sidebands of few-cycle rectangular pulses.     

A scheme for pre-shaping of dispersion-managed solitons

We demonstrate efficacy of shaping Gaussian pulses into dispersion-managed (DM) solitons by dint of a device which includes two fibers with the same group-velocity-dispersion (GVD) coefficients as in the DM system, a frequency-domain filter, and an amplifier. The shaping of a given input pulse is optimized by adjusting values of four free parameters of the cell, viz., lengths of the two fibers, filtering coefficient, and amplification gain, with the objective to achieve the best fit of the transformed pulse to the (numerically found) DM soliton, including systems with the third-order GVD, and with three-step DM maps. Launching reshaped pulses into the DM system, we demonstrate, in direct simulations, their complete stability over indefinitely long propagation distances. We examine sensitivity of the reshaping to deviations of the control parameters from their optimum values, a noteworthy results being very weak dependence on variations of the filtering strength. The dependence of the four control parameters on the width and chirp of the Gaussian input signal is also studied in detail.     

Physics and mathematics of dispersion-managed optical solitons

We review the main physical and mathematical properties of dispersion-managed (DM) optical solitons. Theory of DM solitons can be presented at two levels of accuracy: first, simple, but nevertheless, quantitative models based on ordinary differential equations governing evolution of the soliton width and phase parameter (the so-called chirp); and second, a comprehensive path-average theory that is capable of describing in detail both the fine structure of DM soliton form and its evolution along the fiber line. An analogy between DM soliton and a macroscopic nonlinear quantum oscillator model is also discussed. To cite this article: S.K. Turitsyn et al., C. R. Physique 4 (2003).     

Scheme for the characterization of dispersion-managed solitons

We give a simple new derivation of the ordinary differential equations that describe approximately the behavior of dispersion-managed solitons, and a new scheme for their solution in which the nonlinear dispersive and spectral effects are clearly apparent.     

Black solitons in dispersion-managed fiber transmission systems

In an ideal continuous exponential varying-dispersion fiber, black solitons, like their bright counterparts, can propagate over long distances without being broadened when the weakened nonlinearity that is due to the fiber loss is compensated for by the decreasing dispersion. It is found, however, that in a practical stepwise decreasing-dispersion fiber with N steps the number of steps N required for well-behaved evolution of black solitons in a lossy fiber with negligible distortion and broadening is fewer than for bright solitons. This finding indicates that the stepwise-varying-dispersion in fibers can be more effective for extending the amplifier spacing or reducing amplifier numbers in the high-bit-rate black soliton transmission system than in the corresponding bright soliton transmission system.     

Analysis of enhanced-power solitons in dispersion-managed optical fibers

We analyze pulse propagation in an optical fiber employing a periodic dispersion map. Second-order averaging is used to determine a general evolution equation valid for both return-to-zero and non-return-to-zero pulses in dispersion-managed systems. The equation is then applied to the case of solitons, and an analytic expression for the power enhancement arising from the dispersion management is obtained.     

Persistent oscillations of scalar and vector dispersion-managed solitons

We show that both orthogonal and parallel internal modes exist on the background of a dispersion-managed (DM) soliton in randomly birefringent fibers. The orthogonal modes exist for arbitrarily small values of the dispersion map strength, while the parallel modes exist only when the map strength exceeds a certain threshold value. We demonstrate that initial perturbations of a DM soliton's profile that consist of one or more internal modes, exhibit nearly stable oscillations over very long propagation distances, before decaying into radiation. (c) 2000 American Institute of Physics.     

Carrier-envelope offset phase control: A novel concept for absolute optical frequency measurement and ultrashort pulse generation

The shortest pulses periodically emitted directly from a mode-locked Ti:sapphire laser are approaching the two-optical-cycle range. In this region, the phase of the optical carrier with respect to the pulse envelope becomes important in nonlinear optical processes such as high-harmonic generation. Because there are no locking mechanisms between envelope and carrier inside a laser, their relative phase offset experiences random fluctuations. Here, we propose several novel methods to measure and to stabilize this carrier-envelope offset (CEO) phase with sub-femtosecond uncertainty. The stabilization methods are an important prerequisite for attosecond pulse generation schemes. Short and highly periodic pulses of a two-cycle laser correspond to an extremely wide frequency comb of equally spaced lines, which can be used for absolute frequency measurements. Using the proposed phase-measurement methods, it will be possible to phase-coherently link any unknown optical frequency within the comb spectrum to a primary microwave standard. Experimental studies using a sub-6-fs Ti:sapphire laser suggesting the feasibility of carrier-envelope phase control are presented. Received: 19 August 1999 / Published online: 8 September 1999     

Instability of dispersion-managed solitons in a system with filtering

Unstable behavior of dispersion-managed (DM) solitons in a system with lumped filtering is numerically studied. A variational analysis shows that the system cannot have stable fixed DM soliton solutions when the filter location is improperly chosen. This is because of the unique dynamics of the spectral behavior of DM solitons, which differs from that of standard solitons in fibers with constant dispersion. The instability is confirmed by numerical simulations with and without sliding center frequencies of the filters.     

High-order dispersion-managed solitons for dense wavelength-division multiplexed transmissions

Optimal dense wavelength-division multiplexed transmission is obtained based on high-order periodic dispersion-managed solitons in a dispersion-slope-compensated fiber link.     

Observation of antisymmetric dispersion-managed solitons in a mode-locked laser

We report experimental evidence of antisymmetric solitons in a mode-locked fiber laser with a strong dispersion map. A dispersion-managed soliton breathes as it traverses the dispersion map, and the antisymmetric dispersion-managed soliton can be considered a tightly bound soliton pair with pi phase difference between the component solitons. The antisymmetric soliton is observed only at particular values of the net cavity dispersion.     

Interactions of dispersion-managed solitons in wavelength-division-multiplexed optical transmission lines

We investigate interactions between pulses in dispersion-managed multichannel wavelength-division-multiplexed soliton systems, using an improved variational approximation. The frequency shifts are found to be smallest for moderate, i.e., relatively short-scale, dispersion management. The position shifts increase monotonically with map strength.     

Role of adjacent-pulse overlap in the interaction between dispersion-managed solitons

Periodic breathing of pulse width owing to strong dispersion management leads to significant overlap between adjacent pulses in long-distance fiber-optic transmissions. A striking result is that beyond a critical degree of overlap the interaction forces are no longer increased and are even reduced as the overlap is enhanced.     

Black solitons in dispersion-managed fiber transmission systems: errata

In the referenced Letter,1 a word was misprinted with the opposite meaning. On the fourth line of the left column of p. 158, the second word of the second sentence should be independence, not dependence as printed.     

Carrier-envelope phase measurement using a non phase stable laser

We demonstrate that the phase between the carrier and the pulse envelope of a few-cycle laser pulse can be retrieved from non phase stable laser systems, provided that such laser pulses are about 5 fs long and the repetition rate is in the order of 1 kHz. Our approach is based on online determination of the phase using f-2f interferometry. By a comparison of the self referencing interferometric signal with the photoelectron current emitted into a 7 degree solid angle parallel to the laser polarization, we obtain the absolute value of the carrier envelope phase. This is provided that a Coulomb correction for electron energies below 10 eV can be correctly taken into account. PACS 42.50.Hz; 42.65.Re; 32.80.Rm