Propagation Of Optical Pulses Research Articles

A study of optical solitons of Manakov model describing optical pulse propagation

A study of optical solitons of Manakov model describing optical pulse propagation

Novel optical waves for the perturbed nonlinear Chen-Lee-Liu equation with variable coefficients using two different similarity techniques

In this paper, a new extension of the perturbed nonlinear Chen-Lee-Liu equation as a variable coefficients model represents optical pulse propagation in a monomode fiber is studied. The direct similarity reduction method is used to transform the Chen-Lee-Liu model with variable coefficients to a nonlinear ordinary differential equation and the Jacobi elliptic expansion method is used to solve the reduced equation and as a result, novel optical solitons, periodic, and singular waves have arisen. Then, to prove the physical existence and importance of the presented variable coefficients Chen-Lee-Liu model, another similarity technique is used to transform the Chen-Lee-Liu model to the generalized derivative Schrödinger equation which has known bright and dark soliton solutions. Finally, a graphical representation of the obtained wave solutions according to different structures of the variable coefficients is presented.

Simultaneous temporal and spectral evolution of ultrafast optical pulse propagation using a single bidirectional LSTM network

Numerical simulations of optical pulse evolution are often a cumbersome task, mostly due to the presence of nonlinearities, and standard numerical approaches like splitting methods can be too complex and resource-hungry to compute them. However, under certain conditions, deep learning (DL) techniques can provide accurate alternative approaches to predict such propagation behavior. Here, we show a bidirectional long short-term memory (BiLSTM) network that predicts both temporal and spectral evolution of a short optical pulse going through a 13 m highly nonlinear fiber (HNLF). The BiLSTM performed an RMSE metric of 0.004 and 0.012 for temporal and spectral domains, respectively. A supercontinuum generation was also performed in a 20-cm photonic-crystal fiber, and the BiLSTM returns an RMSE metric of 0.018 and 0.013 for temporal and spectral domains, respectively.

Bright Solitons, dark solitons and periodic wave solutions of Chen–Lee–Liu model

Chen–Lee–Liu (CLL) equation has many applications in optical fibers as well as in plasma physics. It describes the propagation of optical pulse in the monomode fiber. CLL equation is a modification of the nonlinear Schrödinger equation. In this paper, the nonlinear CLL is explored using generalized projective Riccati equation method and two variable [Formula: see text]-expansion method. Consequently, many new solitary wave solutions are achieved in a unique way. These solutions include dark solitons, bright solitons and periodic wave solutions which describe the related physical phenomena. In the end, these solutions are presented in the form of 3D and 2D plots in order to elaborate the wave structure corresponding to the obtained solutions.

Nonreciprocal propagation of optical pulses in a one-dimensional photonic crystal with two Weyl semimetal-based defects

We investigated the nonreciprocal propagation properties of an optical pulse in a one-dimensional photonic crystal containing Weyl semimetal-based defect layers. High optical nonreciprocity, without the need for high-intensity input light sources or external magnetic fields, is the most essential property of the Weyl semimetal. The transfer matrix and Fourier transform techniques are used to obtain the time envelopes of the transmitted pulses. It is demonstrated that the transmitted pulse may attain two different time envelopes by reversing the impinging direction of the input pulse. Then, the effects of the input pulse carrier frequency and time width on the characteristics of the transmitted pulse are presented and shown that reversing the impinging direction of the input pulse has a significant effect on the length and energy of the transmitted pulse. The results may have applications in designing pulse-shaping filters and transferring digital data.

Lie symmetries, bifurcation analysis, and Jacobi elliptic function solutions to the nonlinear Kodama equation

The present article formally studies the propagation of optical pulses in a nonlinear medium governed by the nonlinear Kodama equation. For this purpose, the Lie symmetries group is first adopted for similarity reduction and constructing some exact solutions of the governing equation. After deriving the dynamical system of the nonlinear Kodama equation, its bifurcation analysis is accomplished using the idea of the planar dynamical system. Through perturbing the resultant dynamical system using a trigonometric function, chaotic characteristics of the governing model are analyzed by serving several two- and three-dimensional phase portraits. A sensitivity analysis of the dynamical system is performed using the Runge–Kutta method to ensure that small changes in initial conditions have little impact on solution stability. Finally, using the technique of the planar dynamical system, a number of Jacobi elliptic function solutions (in special cases, bright and dark solitons) are constructed for the nonlinear Kodama equation. It has been shown that bright and dark solitons can be controlled for their width and height effectively by the achievements of the current paper.

Artificial gauge fields in the t-z mapping for optical pulses: Spatiotemporal wave packet control and quantum Hall physics.

We extend the t-z mapping of time-dependent paraxial optics by engineering a synthetic magnetic vector potential, leading to a nontrivial band topology. We consider an inhomogeneous 1D array of coupled optical waveguides and show that the wave equation describing paraxial propagation of optical pulses can be recast as a Schrödinger equation, including a synthetic magnetic field whose strength can be controlled via the spatial gradient of the waveguide properties across the array. We use an experimentally motivated model of a laser-written array to demonstrate that this synthetic magnetic field can be engineered in realistic setups and can produce interesting physics such as cyclotron motion, a controllable Hall drift of the pulse in space or time, and propagation in chiral edge states. These results substantially extend the physics that can be explored within propagating geometries and pave the way for higher-dimensional topological physics and strongly correlated fluids of light.

Dynamical behavior of nonlinear cubic-quartic Fokas-Lenells equation with third and fourth order dispersion in optical pulse propagation

Dynamical behavior of nonlinear cubic-quartic Fokas-Lenells equation with third and fourth order dispersion in optical pulse propagation

Solutions on the periodic background and transition state mechanisms for the higher-order Chen–Lee–Liu equation

Under investigation in this paper is the higher-order Chen–Lee–Liu (HOCLL) equation which can describe optical pulses propagation in the medium involving high-order dispersion and quintic nonlinearity effects. Through Darboux transformation (DT), different types of solutions on the periodic and double-periodic backgrounds are constructed including periodic solutions, solitons, breathers, rogue waves and their coexistences. The modulation instability (MI) conditions and the existence region of rogue waves are analyzed and it is concluded that the region is strictly consistent with the zero frequency MI conditions. In addition, transition state mechanisms of breather-to-soliton and rogue wave-to-soliton are explored.

Nonlinear Optical Pulses in Media with Asymmetric Gain.

A generic novel model governing optical pulse propagation in a nonlinear dispersive amplifying medium with asymmetric (linear spectral slope) gain is introduced. We examine the properties of asymmetric optical pulses formed in such gain-skewed media, both theoretically and numerically. We derive a dissipative optical modification of the classical shallow water equations that highlights an analogy between this phenomenon and hydrodynamic wave breaking. These findings provide insight into the nature of asymmetric optical pulses capable of accumulating large nonlinear phase without wave breaking, a crucial aspect in the design of nonlinear fiber amplifiers.

Spectral stability of elliptic solutions to the short-pulse equation

The short pulse (SP) equation describes the propagation of ultrashort optical pulses in nonlinear media and possesses a Lax pair of the Wadati–Konno–Ichikawa (WKI) type. In this paper, using integrability, we examine the spectral stability of elliptic solutions to the SP equation. Firstly, we analytically give an explicit description of the spectrum of the WKI-Lax operator to the SP equation for elliptic potentials. Then, by constructing the squared-eigenfunction connection between the non-standard linear stability problem (LZ=ΛZ′) and the Lax spectral problem, we prove that the elliptic solutions are spectrally stable with respect to subharmonic perturbations.

Accurate modeling of ultrafast nonlinear pulse propagation in multimode gain fiber

The nonlinear propagation of picosecond or femtosecond optical pulses in multimode fiber amplifiers underlies a variety of intriguing physical phenomena as well as the potential for scaling sources of ultrashort pulses to higher powers. However, existing theoretical models of ultrashort-pulse amplification do not include some critical processes, and, as a result, they fail to capture basic features of experiments. We introduce a numerical model that combines steady-state rate equations with the unidirectional pulse propagation equation, incorporating dispersion, Kerr and Raman nonlinearities, and gain/loss-spectral effects in a mode-resolved treatment that is computationally efficient. This model allows investigation of spatiotemporal processes that are strongly affected by gain dynamics. Its capabilities are illustrated through examinations of amplification in few-mode gain fiber, multimode nonlinear amplification, and beam cleaning in a multimode fiber amplifier.

Ultrafast vortex arrays generated from a mode-locked oscillator with dispersion management.

Herein, we demonstrate the generation of optical vortex arrays pulses using a Sagnac common-path interferometric vortex generator. Hermite-Gaussian (HG) modes with different orders are initially obtained from a SESAM mode-locked laser in the positive dispersion regime. Then, in the interferometric vortex generator, by controlling the phase difference and sheering displacement between two HG modes, optical vortex pulses with different numbers of phase singularities are generated through superposition. The generated HG10 mode has a pulse width of 2 ps and maximum energy of 0.75 nJ. One-dimensional vortex arrays and triangular vortex arrays are also generated, which are formed by HGm0 and HG0n modes, respectively. This work has potential applications in the massive manipulation of microparticles, optical communication, and so on.

Generation of Frequency-Modulated Optical Pulses of the IR Range in a Semiconductor Waveguide Structure with an Implemented Space Charge Wave

Generation of Frequency-Modulated Optical Pulses of the IR Range in a Semiconductor Waveguide Structure with an Implemented Space Charge Wave

Monolithic Saturable Absorber with Gallium Arsenide Nanowires Integrated on the Flexible Substrate for Optical Pulse Generation.

In this work, we demonstrated a kind of flexibly monolithic saturable absorber (SA) with GaAs nanowires (NWs) on polyimide (PI) plastic substrate for broadband optical modulation at 1.0 and 1.5 µm, separately. The monolithic SA sample was prepared by the metalorganic vapor phase epitaxy (MOVPE) method. The crystal structure and element analysis were examined carefully by high-resolution scanning transmission electron microscopy (HRSTEM) and energy-dispersive X-ray spectroscopy (EDX). We observed a high-density distribution of NWs on the flexible substrate by scanning electron microscopy (SEM). In addition, linear and nonlinear optical properties of the sample were examined by testing the photoluminescence and absorption properties, which showed its potential application as an optical switch due to the pure semiconducting properties. After the characterizations, we experimentally demonstrated this monolithic SA for laser modulation at 1.0 and 1.5 µm, which yielded the minimum optical pulse widths of 1.531 and 6.232 µs, respectively. Our work demonstrated such a kind of monolithic flexible NW substrate-integrated device used for broadband optical modulation, which not only eased the integration process of NWs onto the fiber endface, but also proved the potential of easily integrating with more semiconducting nanomaterials (e.g., graphene, MoS2, …) to realize monolithic active flexible photonic systems, such as a microscale phase modulator, delay-line, and so on, paving an easy avenue for the development of both active and flexible photonic devices.

Multi-stage spontaneous symmetry breaking of light in Kerr ring resonators

Symmetry breaking of light states is of interest for the understanding of nonlinear optics, photonic circuits, telecom applications and optical pulse generation. Here we demonstrate multi-stage symmetry breaking of the resonances of ring resonators with Kerr nonlinearity. This multi-stage symmetry breaking naturally occurs in a resonator with bidirectionally propagating light with orthogonal polarization components. The derived model used to theoretically describe the system shows that the four circulating field components can display full symmetry, full asymmetry, and multiple versions of partial symmetry, and are later shown to result in complex oscillatory dynamics - such as four-field self-switching, and unusual pulsing with extended delays between subsequent peaks. To highlight a few examples, our work has application in the development of photonic devices like isolators and circulators, logic gates, and random numbers generators, and could also be used for optical-sensors, e.g. by further enhancing the Sagnac effect.

Effect of dispersion and nonlinearity on ultrashort optical pulse propagation in long-period fiber grating: An analytical investigation

Long-period fiber grating is widely used as an optical component in photonics communication technology. The optical pulse propagation in grating has been studied mostly numerically and some number of studies carried out experimentally. The detailed analytical investigation has not been reported due to the complexity of the mathematical equations. Here, we have investigated analytically the effect of dispersion and nonlinearity on ultrafast optical pulse propagation in long-period fiber grating and derived the expression for transmitted optical pulses because the detailed analytical investigation has not been reported by any authors. The results of the study show how grating-induced overall dispersion and nonlinearity-induced self-phase modulation (SPM) modify the shape of the ultrashort optical pulses when it’s propagating through a length of the grating. The combined effects of dispersion and SPM on the optical pulse evaluation are also analyzed. From the plotted graphs it is investigated that the dispersion of the grating distorted the pulse shape whereas SPM shifts the pulse towards the higher time scale. It is also investigated that the distorted optical pulse due to dispersion is reshaped by the nonlinearity introduced in the medium due to the combined effect of dispersion and SPM. Optical pulse compression, optical limiting and pulse reshaping are also illustrated as a function of excitation intensity.

Transverse instability in nonparaxial systems with four-wave mixing.

We present a two-dimensional coupled nonlinear Schrödinger-like system with spatial diffractions, degree of birefringence, and four-wave mixing. This system describes two physical contexts: optical pulse propagation beyond the paraxial approximation in a weakly birefringence waveguide and light propagation near exciton-polariton resonance in semiconductor superlattice materials. We find that such systems naturally support different types of diffraction profiles, including spherical, ellipsoidal, and hyperbolic structures. We then study the transverse instability of the two-dimensional system caused by an infinitesimal perturbation-induced continuous-wave solution. Also, we find out how various physical parameters, such as nonparaxiality, degree of birefringence, power, and four-wave mixing, affect the modulational instability (MI) process, in particular. We explore the existence of bright solitary wave solutions for the proposed system as the influence of MI is closely related to the latter in a nutshell.

Broadband synchronization of ultrafast pulse generation with double-walled carbon nanotubes

Abstract Double-walled carbon nanotubes have shown competitive properties in broadband optical pulse generation owning to the intrinsic electronic properties. Synchronization of ultrafast optical pulses in multiple wavelengths is a key technique for numerous applications, such as nonlinear frequency conversion, ultrafast pump-probe, coherent Raman scattering spectroscopy, coherent optical synthesis, etc. In this work, we demonstrate the mode-locking and synchronization of 1.55 µm pulses with 1 µm and 1.9 µm pulses via a single saturable absorber based on double-walled carbon nanotubes. The large optical nonlinearity and broadband optical absorption in the double-walled carbon nanotubes enable independent and synchronized mode-locking in >900 nm bandwidth. In addition, we present a creative concept to realize multi-wavelength synchronization from a single laser system. Our results demonstrate a straightforward and feasible approach towards pulse synchronization over ultra-broad bandwidth with flexible wavelength selection in the near-infrared region.

Exact soliton solutions and stability analysis to (3 + 1)-dimensional nonlinear Schrödinger model

In this research, a dynamical (3 + 1)-dimensional nonlinear Schrödinger model (NLSM) is under consideration which is used to model the propagation of ultra-short optical pulses in highly-nonlinear media. This aforementioned model has been widely applied in Bose–Einstein condensates, nonlinear optical fiber communication plasma physics, hydrodynamics, elastic media and other diversified areas of mathematical physics and engineering. This study has two main objectives. Firstly, to obtain some novel solutions in the shape of singular, dark, periodic and plane wave solutions that are innovative and not previously found in the literature. Secondly, an amended extended tanh-function method with modulation instability (MI) is used for this model. As far as we know, this has never been investigated in this manner. The 2-D, 3-D and contour plots have been defined using the required parametric values to support the results of physical compatibility. According to the examined results, the method used in this study to retrieve consisting and conventional solutions is efficient and more immediate in computing and can be thought of as a useful tool in resolving more difficult problems that arise in the field of engineering, physics, mathematics and fiber optics.