Phenomena In Optical Fibers Research Articles

From data to dynamics: Reconstructing soliton collision phenomena in optical fibers using a convolutional autoencoder

In this study, a convolutional autoencoder is constructed to extract and reconstruct the dynamical processes of soliton collisions in optical fibers. The model demonstrates exceptional reconstruction capabilities, accurately capturing the evolution of optical event horizons and reproducing nonlinear phenomena such as complex frequency conversions and energy exchange processes. The reconstruction results show high consistency with the numerical simulations, with RMSE values of 0.0220 and 0.0174 in the temporal and frequency domains, respectively. Additionally, by adjusting the training parameters of the convolutional autoencoder model, its reconstruction performance for nonlinear dynamic processes was further validated. This method is expected to provide a different perspective for studying nonlinear phenomena in optical fibers while reducing the consumption of computational resources.

Breather and rogue wave solutions for the generalized discrete Hirota equation via Darboux–Bäcklund transformation

This paper investigates the Darboux–Bäcklund transformation, breather and rogue wave solutions for the generalized discrete Hirota equation. The pseudopotential of this equation is proposed for the first time, from which a Darboux–Bäcklund transformation is constructed. Starting from a more general plane wave solution and applying the obtained transformation, a variety of nonlinear wave solutions, including three types of breathers, W-shaped soliton, periodic solution and rogue wave are obtained, and their dynamical properties and evolutions are illustrated by plotting figures. The relationship between parameters and wave structures is discussed in detail. The method and technique employed in this paper can also be extended to other nonlinear integrable equations. Our results may help us better understand some physical phenomena in optical fibers and relevant fields.

Traveling wave solutions of generalized seventh-order time-fractional KdV models through He-Laplace algorithm

Non-linear evolution equations play a prominent role in describing a wide range of phenomena in optical fibers, fluid dynamics, electromagnetic radiation, plasma and solid state physics. An important category of non-linear evolution models that characterizes shallow wave phenomena are the Korteweg-de Vries (KdV) models. In this regard, time-fractional Korteweg-de Vries models of seventh order are the main focus of this research. A general KdV seventh-order equation is considered with different coefficients to form Lax, Kaup–Kuperschimdt and Sawada–Kotera–Ito KdV models. An efficient semi-analytical algorithm named as He-Laplace (HLM) is applied for the solution of these models. In this algorithm, Laplace transform is hybrid with homotopy perturbation method (HPM). This study provides important results as non-linear evolution seventh-order models in fractional sense have not been captured through HLM in current literature. Absolute errors are computed and compared with already existing results to confirm the superiority of proposed algorithm over other existing techniques. Numerical and graphical investigations are conducted to evaluate the approximate series form solutions. The dynamic behavior of fractional parameter is observed by calculating residual errors and plotting two dimensional diagrams throughout the fractional-domain. Analysis confirms that the proposed methodology provides an effective and convenient way for solving fractional KdV models.

Erratum: Predictable and unpredictable phenomena in optical fibers for space-division/mode-division multiplexing transmission: statistical analysis of coupling and mysterious behavior of modes [IEICE Electronics Express Vol. 17 (2020) No. 15 pp. 20202001

Erratum: Predictable and unpredictable phenomena in optical fibers for space-division/mode-division multiplexing transmission: statistical analysis of coupling and mysterious behavior of modes [IEICE Electronics Express Vol. 17 (2020) No. 15 pp. 20202001

Predictable and unpredictable phenomena in optical fibers for space-division/mode-division multiplexing transmission: statistical analysis of coupling and mysterious behavior of modes

The transmission capacity of single-mode single-core fibers is approaching the limit of about 100 Tbps owing to nonlinearity and the fiber fuse, which limit the input signal power To avoid the so-called capacity crunch and dramatically increase the transmission capacity, a new approach utilizing space-division multiplexing (SDM) and mode-division multiplexing (MDM) has been proposed and demonstrated In these new multiplexing technologies, a problem that is unprecedented in conventional single-mode fibers, namely, the crosstalk between transmission channels, arises Although the input signal channels are mixed through at the output end, the signal channel can be identified using multiple-input multiple-output (MIMO) signal processing technology at the output end However, even using the MIMO digital signal processing technology, the problem that the computation time increases with the number of channels remains, resulting in increased latency, and so the number of channels is limited To design a transmission system using the SDM and MDM technologies, the crosstalk should be analyzed precisely However, the origin and behavior of crosstalk are different in SDM using multicore fibers (MCFs) and in MDM using few-mode fibers (FMFs) The behavior of crosstalk in single-mode MCFs is predictable to some extent by statistical analysis, and the system can be designed by considering the results of the analysis On the other hand, the behavior of crosstalk of FMFs is less predictable Since the mode launched at the input end is not the eigenmode, mode discrimination or accurate mode demultiplexing is difficult using a conventional mode demultiplexer In addition, the eigenmode itself of FMFs is not always the hybrid mode predicted by the conventional theory but sometimes a linearly polarized (LP) mode, contradicting the conventional theory In other words, the demultiplexed signal always involves crosstalk regardless of the transmission distance, and the quantity of crosstalk cannot be analyzed statistically Therefore, the crosstalk and its behavior are unpredictable In spite of these unpredictable phenomena, the signal channel can be identified using the MIMO signal processing as in single-mode MCFs This means that the MDM technology using FMFs is established in the engineering or inductive logic sense, but still involves unexplained phenomena in the scientific or deductive logic sense In this review, we discuss the predictable behavior of crosstalk in single-mode MCFs and also the unpredictable behavior of crosstalk in FMFs

Protecting Physical Communications in 5G C-RAN Architectures through Resonant Mechanisms in Optical Media.

Future 5G networks are characterized by three basic ideas: enhanced mobile broadband communications, massive machine-type communications, and ultra-low-latency communications. Any of these requirements needs, to be fulfilled, the implementation of high-efficiency technologies at all levels. This includes some of the costliest mechanisms in terms of computational time and bitrate: information protection solutions. Typical techniques in this area employ complex algorithms and large protocol headers, which strongly reduces the effective baud rate and latency of future 5G networks and communications. This is especially relevant in the access network, which in 5G networks will follow a cloud-based architecture, where thousands of different devices must communicate, before aggregating all those streams to be sent to the backbone. Then, new and more efficient mechanisms are needed in the cloud radio access networks (C-RAN) for future 5G systems. Therefore, in this paper it is proposed a novel information protection scheme for C-RAN architectures based on resonant phenomena in optical fibers communicating the fronthaul and backhaul in 5G networks. Resonant structures and physical nonlinearities generate a chaotic signal which may encrypt and hide at physical level every communication stream in a very efficient manner. To evaluate the proposed mechanism, an experimental validation based on simulation techniques is also described and results discussed.

Analytical Solutions to Generalized Nonlinear Schrödinger Equation by Adomian Decomposition Technique

We study the higher-order nonlinear Schrödinger equation which takes care of the second as well as third order dispersion effects, cubic and quintic self phase modulations, self steepening and nonlinear dispersion effects. Taking advantage of the initial condition, we transform theprevious equation into a nonlinear functional equation to which we apply a powerful analytical method called the Adomian decomposition method. We compute the Adomian’s polynomials of corresponding infinite series solution. Assuming that the initial condition and all its derivatives converge to zero sufficiently rapidly as the time approaches to infinity, we established the convergence of the previous series. The last part of the paper describes applications resulting from nonlinear propagation phenomena in optical fibers. Numerical simulations are developed and it is further shown that comparison with other results yields a good qualitative agreement. These results demonstrate the robustness of the proposed method.

Modulational instability and higher order-rogue wave solutions for the generalized discrete Hirota equation

This paper investigates the modulational instability and higher order-rogue waves in the generalized discrete Hirota system. The Lax pair and conservation laws for this system are constructed. Then the existent conditions for its modulational instability to form the rogue waves are given starting from the plane wave solution. Furthermore, the higher-order discrete rogue waves of this system are reported using the novel discrete version of generalized perturbation (n,N−n)-fold Darboux transformation. Finally, the dynamical behaviors of the strong and weak interactions of these higher-order discrete rogue waves are discussed analytically and numerically, which exhibits abundant nonlinear wave structures. These results may be useful for understanding some physical phenomena in optical fibers and relevant fields.

Modulational instability and higher-order rogue wave solutions for an integrable generalization of the nonlinear Schrödinger equation in monomode optical fibers

We consider the integrable generalization of the nonlinear Schrodinger equation that arises as a model for nonlinear pulse propagation in monomode optical fibers. The existent conditions for its modulational instability to form the rogue waves is given from its plane-wave solutions. We propose a generalized $(n,N-n)$ -fold Darboux transformation for this system by using the Nth-order Darboux matrix, Taylor expansion, and a limit procedure. As an application, we use the generalized perturbation $(1,N-1)$ -fold Darboux transformation to generate higher-order rogue wave solutions of this system. The dynamics behavior of the first-, second-, and third-order rouge wave solutions are shown graphically. These results may be useful for understanding some physical phenomena in optical fibers.

Soliton's eigenvalue based analysis on the generation mechanism of rogue wave phenomenon in optical fibers exhibiting weak third order dispersion.

One of the extraordinary aspects of nonlinear wave evolution which has been observed as the spontaneous occurrence of astonishing and statistically extraordinary amplitude wave is called rogue wave. We show that the eigenvalues of the associated equation of nonlinear Schrödinger equation are almost constant in the vicinity of rogue wave and we validate that optical rogue waves are formed by the collision between quasi-solitons in anomalous dispersion fiber exhibiting weak third order dispersion.

Nonlinear effects upon collisions of optical pulses: Tunneling, blocking, and trapping

The regimes of reflection, trapping, and tunneling of light pulses upon their collision in nonlinear media are considered. General conditions for the occurrence of these phenomena in optical fibers and nonlinear crystals are formulated on the basis of an analogy with quantum mechanics.

Program committee chairman

271 The Fourth Russian Seminar on Fiber Lasers took place in Ul’yanovsk on April 19–22, 2010. The event upholds traditions of the Seminars in Novosibirsk (2007), Saratov (2008), and Ufa (2009) [1]. The Sem inar was organized by the Ul’yanovsk State University. Components of fiber lasers, various configurations of fiber lasers and amplifiers, nonlinear phenomena in optical fibers, applications of fiber lasers in communi cations and technology, and fiber optic sensors were the Program highlights. More than 100 participants from Novosibirsk, Snezhinsk, Kazan, Samara, Sara tov, Ul’yanovsk, Moscow, Fryazino, and other Russian cities presented 70 reports.

Particle swarm optimization on threshold exponential gain of stimulated Brillouin scattering in single mode fibers

We implement a particle swarm optimization (PSO) algorithm to characterize stimulated Brillouin scattering phenomena in optical fibers. The explicit and strong dependence of the threshold exponential gain on the numerical aperture, the pump laser wavelength and the optical loss coefficient are presented. The proposed PSO model is also evaluated with the localized, nonfluctuating source model and the distributed (non-localized) fluctuating source model. Using our model, for fiber lengths from 1 km to 29 km, the calculated threshold exponential gain of stimulated Brillouin scattering is gradually decreased from 17.4 to 14.6 respectively. The theoretical results of Brillouin threshold power predicted by the proposed PSO model show a good agreement with the experimental results for different fiber lengths from 1 km to 12 km.

Analogs of time-dependent quantum phenomena in optical fibers

Review of the paraxial approximation to the problem of light beams propagating in optical fibers is presented. The analogy of time-dependent integrals of motion for the quantum system and space-dependent invariants for the radiation in inhomogeneous optical waveguides is elucidated. A specific tomographic probability distribution associated with the light-pulse profile is considered analogously to tomographic probabilities in quantum mechanics. The new inequality is presented for the tomographic probability.

Nonlinear phenomena in optical fibers with an impurity

This paper is devoted to a study of the features of the nonlinear conversion of radiation in various types of optical fibers. It is found that, when a narrow-band radiation source is used, the spectrum of the converted radiation in a fiber-optic ring apparatus shows significant broadening, whose character depends on the type of optical fiber. It is shown that the broadening of the radiation spectrum results from partially degenerate four-wave mixing. Solutions are found in explicit form that satisfy boundary conditions that correspond to the experimental conditions.

Modal analysis of the self-imaging phenomenon in optical fibers with an annular core

We investigate the occurrence of self-images, or Talbot images, in a spatially multimode field that propagates along an optical fiber whose core has an annular-shaped cross section. By use of full-vectorial modal analysis, we study the effect of the transverse fiber dimensions on the self-imaging properties. According to our analysis, good self-images can be expected when the fiber core is thin and the modes are far from their cutoffs. However, as the core diameter is made larger to increase the number of modes available in the imaging, the general self-imaging properties tend to deteriorate.

Quaternion Approach to PMD and PDL Phenomena in Optical Fiber Systems

In this paper, we introduce the concept of quaternions (which is a generalization of the complex numbers) and quaternion calculus and demonstrate how this theory may be used to simplify the treatment of polarization phenomena in optical fibers. We apply quaternion calculus to two examples: 1) the description of polarization-dependent loss (PDL) elements and concatenation of such and 2) the description of pulse dynamics and broadening in transmission lines with both polarization-mode dispersion (PMD) and PDL. Finally we present some novel results from the investigation of pulse broadening in a simple system comprising a PMD element, followed by a perfect polarizer.

Analysis of optical pulse propagation with two-by-two (ABCD) matrices.

We review and extend the analogies between Gaussian pulse propagation and Gaussian beam diffraction. In addition to the well-known parallels between pulse dispersion in optical fiber and cw beam diffraction in free space, we review temporal lenses as a way to describe nonlinearities in the propagation equations, and then introduce further concepts that permit the description of pulse evolution in more complicated systems. These include the temporal equivalent of a spherical dielectric interface, which is used by way of example to derive design parameters used in a recent dispersion-managed soliton transmission experiment. This formalism offers a quick, concise, and powerful approach to analyzing a variety of linear and nonlinear pulse propagation phenomena in optical fibers.

Polarization in Optical Fibers

Optical fibers exhibit particular polarization properties. The guided electromagnetic fields in optical fiber waveguides are called inhomogeneous plane waves since their amplitudes are not stable within the plane wave and the fields are characterized, in most cases, by non-transverse components. In the description of polarization phenomena in optical fibers there are generally two approaches [1]. The first one treats an optical fiber as an optical waveguide in which light being a kind of electromagnetic wave of optical frequencies can be guided in the form of waveguide modes. This approach identifies basic polarization eigenmodes of a fiber and relates them to the polarization state of the guided light. Changes in output polarization are described in terms of polarization-mode coupling due to birefringence changes acting as perturbations along the fiber. Another approach treats an optical fiber like any other optical device which transmits light and the fiber can be divided into separated sections behaving like . polarization state shifters. Here, polarization evolution in a fiber can be described by one of the three general formalisms: by the Jones vectors and matrices formalism, by the Stokes vectors and Mueller matrices formalism, or by the Poincare sphere representation. Since optical fibers allow very large propagation distances even very small birefringence effects can cumulate along fiber and their random distribution over the large lengths causes polarization properties of guided light generally difficult to determine. Although polarization effects in optical fibers have initially played a minor role in the development of light-wave systems their importance is still growing. Before 1980 it was impossible to exploit the polarization modulation in a fiber for

Investigation and application of the frustrated-total-internal-reflection phenomenon in optical fibers

A detailed investigation of the frustrated-total-internal-reflection (FTIR) phenomenon in silica-glass-based optical fibers and its application to simple intensity-modulated strain and pressure sensors is presented. Such sensors may be readily fabricated with silica-based fibers and can be easily modified with sapphire fibers for high-temperature industrial applications where conventional silica-based fiber sensors are not feasible. We present the all-fiber FTIR sensor and show good correlation between theory and experiment. We also present results for the design and implementation of a prototype FTIR-based fiber pressure sensor.