非线性单模光纤中源啁啾孤子相互作用

本文采用分步傅氏变换法对非线性单模光纤中源啁啾孤子相互作用进行了详细的数值研究.所得结果揭示了先源啁啾对孤子相互作用影响的本质,为设计光源啁啾情况下的孤子传转系统提供了依据.     

Soliton interaction in strongly dispersion-managed optical fibers

We derive an expression for the speed with which neighboring solitons attract or repel each other in dispersion-managed fiber systems. We show that the collapse distance can be increased by an order of magnitude by use of quasi-solitons.     

Soliton coupling in birefringent optical fiber with third-order dispersion

Nonlinear coupling of polarized solitons in birefringent optical fiber in the presence of third-order dispersion is considered in the framework of the coupled nonlinear Schrödinger equations. The influence of third-order dispersion on the interaction between solitons is investigated. For sufficiently strong third-order dispersion the interaction may even become repulsive. The stable conditions for solitons of partial pulses are analyzed and amplitude threshold, which decreases with third-order dispersion coefficient decreasing, for the capture of solitons of partial pulses into a coupled two-component pulse is obtained.     

Second harmonic generation in birefringent optical fibers

Second harmonic generation in optical fibers is investigated. A scheme to combine material, modal and geometrical dispersion to achieve phase matching is proposed. Conversion efficiency, as a function of the fiber's parameters and the incoming electric field strength, is computed.     

Modulation instabilities in randomly birefringent two-mode optical fibers

Modulation instabilities in the randomly birefringent two-mode optical fibers(RB-TMFs) are analyzed in detail by accounting the effects of the differential mode group delay(DMGD) and group velocity dispersion(GVD) ratio between the two modes, both of which are absent in the randomly birefringent single-mode optical fibers(RB-SMFs). New MI characteristics are found in both normal and anomalous dispersion regimes. For the normal dispersion, without DMGD,no MI exists. With DMGD, a completely new MI band is generated as long as the total power is smaller than a critical total power value, named by Pcr, which increases significantly with the increment of DMGD, and reduces dramatically as GVD ratio and power ratio between the two modes increases. For the anomalous dispersion, there is one MI band without DMGD. In the presence of DMGD, the MI gain is reduced generally. On the other hand, there also exists a critical total power(Pcr), which increases(decreases) distinctly with the increment of DMGD(GVD ratio of the two modes) but varies complicatedly with the power ratio between the two modes. Two MI bands are present for total power smaller than Pcr, and the dominant band can be switched between the low and high frequency bands by adjusting the power ratio between the two modes. The MI analysis in this paper is verified by numerical simulation.     

Soliton switching in twin-core fibers with gain and loss

Soliton propagation and switching in twin-core nonlinear fibers with gain and loss have been investigated based on a pair of coupled nonlinear Schr?dinger equations. We have found the fiber with equal amount of gain in both cores has the minimum ascending energy Δɛ of 1.5K, while the fiber with a certain amount of gain in one core and the same amount of loss in the other core has the minimum switching thresholdɛ _th of 2.05K. A new vector field is defined and its potential function is derived, which explains the switching behavior of the minimumɛ _th switch satisfactorily.     

Soliton models in resonant and nonresonant optical fibers

In this review, considering the important linear and nonlinear optical effects like group velocity dispersion, higher order dispersion, Kerr nonlinearity, self-steepening, stimulated Raman scattering, birefringence, self-induced transparency and various inhomogeneous effects in fibers, the completely integrable concept and bright, dark and self-induced transparency soliton models in nonlinear fiber optics are discussed. Considering the above important optical effects, the different completely integrable soliton models in the form of nonlinear Schrödinger (NLS), NLS-Maxwell-Bloch (MB) type equations reported in the literature are discussed. Finally, solitons in stimulated Raman scattering (SRS) system is briefly discussed.     

Suppressing chromatic dispersion fluctuation for broadband optical parametric gain in highly nonlinear tellurite microstructured optical fibers

Optical Review - We investigate the effect of chromatic dispersion fluctuation on the performance of fiber optical parametric amplification (FOPA) using tellurite hybrid microstructured optical...     

Anomalous pulse spreading in birefringent optical fibers with polarization-dependent losses

A combination of polarization-mode dispersion and polarization-dependent losses in optical fibers may lead to anomalous pulse spreading. We both calculate this effect and confirm its existence by an experimental demonstration.     

Bright and dark solitons in the normal dispersion regime of inhomogeneous optical fibers: Soliton interaction and soliton control

Symbolically investigated in this paper is a nonlinear Schrödinger equation with the varying dispersion and nonlinearity for the propagation of optical pulses in the normal dispersion regime of inhomogeneous optical fibers. With the aid of the Hirota method, analytic one- and two-soliton solutions are obtained. Relevant properties of physical and optical interest are illustrated. Different from the previous results, both the bright and dark solitons are hereby derived in the normal dispersion regime of the inhomogeneous optical fibers. Moreover, different dispersion profiles of the dispersion-decreasing fibers can be used to realize the soliton control. Finally, soliton interaction is discussed with the soliton control confirmed to have no influence on the interaction. The results might be of certain value for the study of the signal generator and soliton control.     

Soliton complexes and flat-top nonlinear modes in optical lattices

We describe a continuous analog of the quasirectangular flat-top nonlinear modes earlier found for discrete nonlinear models. We show that these novel nonlinear modes can be understood as multi-soliton complexes with either in-phase or out-of-phase neighboring solitons trapped by the periodic potential of the lattice. We demonstrate a link between the flat-top states and the truncated nonlinear Bloch waves, and discuss how these nonlinear localized modes can be monitored experimentally in photonics and Bose–Einstein condensates. PACS 42.65.Tg; 42.65.Jx; 03.75.Lm     

Interference method of measuring the extinction coefficient of birefringent optical fibers

The extinction coefficient of a birefringent optical fiber (the ratio between the radiation power output of the polarization mode and the radiation power transferred from this mode to another one) characterizes the capability of a birefringent fiber to retain the polarization state of the radiation. In relatively short birefringent fibers (1–100 m), the extinction coefficient may reach 10⁴–10⁶. Such high values of the extinction coefficient are difficult to measure by standard techniques (excitation of one polarization mode by an incoherent source with subsequent recording of the light intensity at the output of the analyzer). An interference method of measuring the extinction coefficient of birefringent fibers is suggested. It is based on using a coherent source and measuring interference oscillations caused by an additional phase modulation at the input of the fiber. This method does not require precise polarization matching between the laser source and fiber and considerably loosens requirements for the polarizer-analyzer extinction and resolution of the photodetector. As a result, using simple standard components (semiconductor laser, film polarizer, and photodetector), one can measure extinction coefficient as high as 10⁶. The suggested interference method of measuring the extinction coefficient of birefringent fibers receives a theoretical analysis, and experimental data obtained for 2- to 1000-m-long fibers are presented.     

Experimental observation of orthogonally polarized time-delayed optical soliton trapping in birefringent fibers

Propagation of two orthogonally polarized time-delayed optical solitons in low-birefringence optical fiber is studied experimentally. We demonstrate soliton trapping and collisions and also the ability to control the separation and shape of soliton pulses by varying the power at the input of the fiber.     

Short optical pulse polarization dynamics in a nonlinear birefringent doped fiber

Numerical solutions are obtained of the full self-consistent system of equations for the counter, rotating polarization components of the field of a short optical pulse propagating in a nonlinear birefringent fiber and in the ensemble of the energy-level degenerate doped resonance atoms implanted in the fiber material. In every cross section of the fiber, the ellipticity of the polarized wave experiences a complex evolution in time accompanied by rapid changes of the azimuthal angle due to the interplay of the dispersion and the Kerr nonlinear self-and cross-phase modulation. The reciprocal effect of the impurities on the traveling pulse causes oscillations of the pulse envelope that can completely distort the shape of the input signal, while the resonance absorption can drive the birefringence process from the nonlinear regime back to the linear one.     

Soliton squeezing in a highly transmissive nonlinear optical loop mirror

A perturbation approach is used to study the quantum noise of optical solitons in an asymmetric fiber Sagnac interferometer (a highly transmissive nonlinear optical loop mirror). Analytical expressions for the three second-order quadrature correlators are derived and used to predict the amount of detectable amplitude squeezing along with the optimum power-splitting ratio of the Sagnac interferometer. We find that it is the number-phase correlation owing to the Kerr nonlinearity that is primarily responsible for the observable noise reduction. The group-velocity dispersion affecting the field in the nonsoliton arm of the fiber interferometer is shown to limit the minimum achievable Fano factor.     

Polarization-induced pulse spreading in birefringent optical fibers with zero differential group delay

The polarization properties of concatenations of trunks of birefringent fibers and elements with polarization-dependent losses are analyzed. We show both theoretically and experimentally that the concatenation can have zero differential group delay over a whole range of wavelengths but that a pulse propagating down the concatenation can still experience significant pulse spreading. In this example the two main methods used for characterizing polarization mode dispersion in optical fiber systems, i.e., Jones matrix eigenanalysis and the interferometric method, give different results. This counterintuitive example underlines the need for a careful assessment of the basic concepts related to polarization effects in the presence of polarization-dependent losses.     

Quasi-linear pulses in birefringent fibers

The evolution of quasi-linear optical pulses in birefringent fibers, with strong dispersion-management, is studied analytically. The nonlinear terms of the Gabitov–Turitsyn equations (GTE) are analyzed asymptotically. The total spectral intensity, for a lossless system, is found to be an invariant of propagation, while for a lossy system it is dependent on the relative position of the amplifier in the dispersion map.OCIS Codes. 060.2330; 060.4370; 060.5530; 190.4370; 260.2030