Journal of Nonlinear Optical Physics & Materials

Silver (Ag)-doped and un-doped Zinc sulfide (ZnS) nanostructures (NSs) with different concentrations (ZnS: Ag 1%, 3%, 5%, 10%) were prepared by using the chemical method at room temperature. Doping of Ag into ZnS nanostructures modified its optical properties. The size and crystallinity of stabilized ZnS:Ag nanostructures are confirmed with SEM (Scanning electron microscopy) and XRD (X-ray diffraction). The formation of nanostructures is justified by UV-visible absorption spectra. The luminescence intensity of nanostructures has increased drastically at ZnS:Ag-10% and is characterized by a fluorescence spectrometer. The nonlinear optical properties are found by using the Z-scan setup and act as optical limiters. The nonlinear absorption coefficient $(\beta )$ and nonlinear refractive index ($n_2)$ are in the range of 10${}^{-9}$cm/W and 10${}^{-14}$cm²/W, respectively. The optical limiting threshold value is 0.11 J/cm². These nanostructures can be used as optical limiters.

In this work, investigation of the W-chirped solitons and modulation instability are addressed in nonlinear optic fibers where cubic-quintic and parabolic law parameters are used. For this reason, the modified cubic-quintic complex Ginzburg–Landau equation with parabolic law nonlinearity is employed. Using the sub-ODE method, the chirp component and combined chirped soliton solutions, including rational soliton solutions, are obtained. Using specific parameters of the nonlinear structure, one can identify dark and bright solitons. For a suitable constant parameter of the chirp component, the W-chirped bright as well as the combined bright-dark solitons are displayed via the 3D plots. The linear stability analysis of the plane wave is used to derive an expression of the modulation instability spectrum that is employed to show the effects of the nonlinear parameters in normal and anomalous dispersion regimes. It is pointed out that both cubic and quintic parameters can enlarge or reduce the bandwidth of the modulation instability. Through the numerical simulation of the continuous wave, it becomes apparent that for suitable optical fiber parameter values, modulated wave objects are formed to exhibit mild oscillations. For specific wavenumber excitation, another modulated wave object is depicted to show how the unstable mode can switch to the stable mode for the long-time evolution of the continuous wave. The obtained results could certainly open a new future for signal treatment in optical fiber, where parabolic law is considered.

The advancement of crystal growth and characterization methods allows us to investigate new substances with excellent nonlinear optical characteristics. To synthesize nonlinear optical material L-histidine hydrochloride hydrate (L-HHCLH), the gradual evaporation process was used. The produced samples were characterized by single-crystal X-ray crystallography, Fourier transform infrared (FTIR) and Raman spectroscopy, UV–visible (UV–Vis) spectroscopy, second harmonic generation (SHG) test, dielectric, and mechanical investigations. The L-HHCLH sample was crystallized in an orthorhombic structure with the P2₁2₁2₁ space group, as verified by the crystallographic data. FTIR and Raman spectroscopy were applied to examine the molecular vibrations and availability of the functional groups of the compound. The L-HHCLH is significantly transparent across the UV and visible ranges, as shown by the UV–Vis spectra measurements. The bandgap of L-HHCLH is 5.45 eV. The SHG test showed that the L-HHCLH crystals produced a significant amount of SHG output thrice that of the potassium dihydrogen phosphate (KDP) sample. The frequency dependences of the dielectric parameters were investigated in the dielectric tests. With increasing frequency, both the dielectric constant and loss dropped exponentially. The crystal hardness was determined using a microhardness test.

In this paper, an ultra-compact high capability silicon-based waveguide with a high nonlinear coefficient and engineered dispersion was designed for frequency combs generation and demultiplexing of these combs. In the first part of the structure, a silicon waveguide with two zero-dispersion wavelengths, 1552nm and 2350nm, and a length of 4mm was used to generate optical frequency combs using the four-wave mixing method. Considering the high nonlinear coefficient of $91.695{(\mathrm{\text{Wm}})}^{-1}$ in the waveguide, an input pump power of 500mW was applied to the waveguide at near-zero-dispersion wavelengths of 1552nm. The output comb spectrum of the waveguide was obtained after the length of 4mm with a spectral bandwidth of 400nm and a free spectral range of 5nm. Additionally, by similar pumping at wavelengths of 1553nm and 1555nm to this waveguide, optical frequency combs with a free spectral range of 2nm and a spectral bandwidth of 150nm were obtained. In the second part of the structure, to isolate the optical frequency combs, the given waveguide was expanded to generate an SOI demultiplexer with micro-ring resonator filters, which could separate optical frequency combs with the wavelength of 1555nm, 1557nm, 1559nm, and 1561nm due to the selection of suitable values for the radius of the ring resonators. The mean transmission efficiency, spectral bandwidth, and quality factor were obtained to be 99.51%, 0.275nm, and 5675, respectively. The channel spacing in the proposed demultiplexer was 2nm and the minimum and maximum crosstalk were −36dB and −11.3dB.

In this paper, the exact solitary wave solutions for the generalized nonlinear (NL) Schrödinger equation with parabolic NL law employing the generalized $(G^{\prime }/G)$-expansion technique, the improved $tan(\varphi /2)$-expansion technique and the modified exp-function technique are acquired. Different sets of exponential function solutions are acquired relying on a map between the considered equation and an auxiliary ordinary differential equation (ODE). The obtained solutions are concluded in several of the hyperbolic and trigonometric forms based on diverse restrictions between parameters involved in equations and integration constants that appear in the solution. A few significant ones among the reported solutions are pictured to perceive the physical utility and peculiarity of the considered model utilizing mathematical software. For more analysis, the modulation instability (MI) analysis of the proposed model with normal derivatives is also carried out for parabolic NL law. The main aim of this research is that one can visualize and update the knowledge to overcome from the most common methods to solve the ODEs and partial differential equations (PDEs). We demonstrated that these solutions validated the program using Maple and found them to be correct. The proposed methodology for resolving NLPDEs has been designed to be effectual, unpretentious, expedient, and manageable. Finally, the existence of the solutions for the constraint conditions is also shown.

Graphene, with its broadband optical properties and high optical nonlinearity, shows promise as an ultrathin material compatible with CMOS technology for all-optical signal processing in integrated photonics. This paper presents simulation, analysis, and design of a novel graphene-integrated nonlinear hybrid plasmonic waveguide. Finite element simulations study the Kerr nonlinear effect of extra graphene layers. The enhanced nonlinear parameter of $\gamma =7.36\times 10^8$W${}^{-1}$Km${}^{-1}$ and nonlinear figure-of-merit (FOM) of 2.10 achieved at 1,550nm exceed those of silicon-on-insulator (SOI) hybrid plasmonic waveguides. The proposed graphene-integrated hybrid plasmonic waveguide (GHPW) demonstrates high Kerr nonlinearity and FOM, indicating potential for nonlinear all-optical signal processing.

The objective of this paper is to obtain some solitary solutions of (2+1)-dimensional variable coefficient nonlinear Schrödinger (NLS) equations through computerized symbolic computation. By applying the $F$-expansion and homogeneous balance method, two soliton solutions are constructed for the NLS equations, which provide a model of the interaction between two waves. Consequently, the solitary solutions are obtained in different forms of dynamical structures. Moreover, the propagation behavior of the resulting solitonary solutions is discussed. The results have rich physical structures that are helpful to explain the nonlinear soliton phenomena in nonlinear optics and plasma physics.

The theory of photorefractive (PR) screening solitons is regarded as a well-established theory and solidly confirmed experimentally. In this paper we focus main attention on the dynamics of bright and dark beams in PR crystals in the context of soliton generation. The analysis was carried out within the microscopic theory in opposition to the commonly used macroscopic theory. It has been shown that the standard solution may be drastically different from the solution based on the microscopic model. This paper presents a new formulation of the adiabatic approximation and the corresponding temporal equation for the formation of the electric field in PR crystals. A novel time constant has been introduced to describe the total duration of the transition state. The obtained results were compared with numerical solutions. In this way, we developed a description of the dynamics of (1+1)D beams in PR materials consistent with the microscopic model.