Journal of Nonlinear Optical Physics & Materials

Topological insulators (TIs) are a new type of electronic material with the insulating bulk state and topologically protected conducting surface/edge state. TI materials exhibiting outstanding optical properties containing high carrier mobility, ultrahigh refractive index, wide operating spectral range, and dynamic tunability play an important role in optical functional devices. Especially, the TI materials with special topological energy bands possess high nonlinear optical coefficient, superior to conventional semiconductor and two-dimensional materials. The nonlinear optical characters of TIs are expected to realize highly efficient nonlinear optical conversion, nonlinear absorption, and all-optical switching, terahertz emission. TIs will provide a new platform for the interaction between light and matter as well as the development of nonlinear optics. In this review, we conclude current advances about some research on TI-based nonlinear optical effects and related devices, and give a prospect of potential applications for TIs in nonlinear optics.

The copper oxide nanoparticles (CuO NPs) were synthesized via solution combustion approach with Bengal gram powder as a fuel. The XRD analysis confirms the monoclinic structure of CuO NPs. FT-IR spectrum reveals the formation of CuO NPs. SEM studies show that the NPs are nearly spherical, and the elemental composition was confirmed by EDAX. The absorption spectra revealed a direct optical band gap of 1.50eV. DFT calculations were performed to determine the HOMO–LUMO energy bandgap and found to be 1.72eV, which is in good agreement with the experimental value. The Z-scan technique was used to investigate the third-order nonlinear optical (NLO) characteristics using DPSS continuous wave laser (532nm, 200mW). A high reverse saturation absorption and negative nonlinear refractions were observed. Third-order NLO parameters $\beta$, $n_2$ and ${\chi }^{(3)}$ were found to be $19.6\times 10^{-5}$cm/W, $-1.12\times 10^{-8}$cm²/W and $5.97\times 10^{-7}$esu, respectively. The CuO NPs also displayed strong optical limiting behavior with a limiting threshold of 2.11kW/cm².

The mathematical model of the PT media with variable coefficients is introduced, and the spatiotemporal vortex and multi-pole mode solutions are derived by the bilinear transformation method. Then, the modulation propagation of the solutions is also studied. In addition, a novel control approach for constructing the distribution and the quantity of multi-vortex solitons by using different nonlinear hyperbolic tangent function are proposed. Finally, the effectiveness of the method is validated.

The Kaup–Newell equation is used to model sub-picoseconds pulses that travel throughout optical fibers. The fractional-order perturbed Kaup–Newell model, which represents extensive waves parallel to the field of magnetic, is examined. In this paper, two analytical techniques named, improved F-expansion and generalized exp$(-\varphi (\zeta ))$-expansion techniques, are employed and new analytical solutions in generalized forms like bright solitons, dark solitons, multi-peak solitons, peakon solitons, periodic solitons and further wave results are assembled. These soliton solutions and other waves findings have important applications in applied sciences. The configurations of some solutions are shown in the form of graphs through assigning precise values to parameters, and their dynamics are described. The illustrated novel structures of some solutions also assist engineers and scientists in better grasping the physical phenomena of this fractional model. A comparison analysis has been given to explain the originality of the current findings compared to the previously achieved results. The results of computer simulations show that the procedures described are effective, simple, and efficient.

TOAD or Tera Hertz Optical Asymmetric Demultiplexer is an optical switch. Using this switch, we have invented an optical comparator. This optical comparator circuit is very simple in structure with a higher speed (200 Gbps) and finds useful application in optical computation and communication network system. We have simulated all three outputs in detail and shown the eye diagram of all three outputs of the optical comparator. We found high values of extinction ratio (ER), contrast ratio (CR), and quality factor (Q value) for the three outputs of the comparator.

The new organic 2-amino-5-chloropyridinium phenoxyacetate (2A5CPA) nonlinear optical (NLO) crystal was synthesized and grown from methanol solvent by slow evaporation method successfully. The complete 2A5CPA crystal structure was solved by single crystal XRD analysis and it indicates that the 2A5CPA crystal belongs to the tetragonal crystal system with the space group P4₁2₁2. From the structure, the possible hydrogen bonding interactions have been analyzed. The presence of distinctive functional peaks in the 2A5CPA crystal was affirmed by FTIR analysis. The optical investigation reveals that the crystal was completely transparent in the UV–Vis–NIR region. The TG-DTA investigation assured that the 2A5CPA compound is thermally stable up to 134°C without any decomposition. The sharp endo thermic peak at 205°C in the DTA trace indicates the melting point of the crystal. The broad emissive band at 382nm implies the violet emission characteristics of the 2A5CPA crystal. The dielectric study of the 2A5CPA crystal portrays the normal behavior to that of optical materials. The high work-hardening coefficient of 2.94 indicates the soft material nature of the crystal. The LDT value of the 2A5CPA crystal is estimated as 0.6135GW/cm². The third-order NLO properties of the 2A5CPA crystal were analyzed through Z-Scan experiment.

The properties of nonlinear optical (NLO) are examined, and the results confirm the 2.19eV HOMO–LUMO mismatch. In the AlPc cluster, certain functional bond lengths and bond angles have been observed. Quantum chemical methods (density functional theory (DFT) and time-dependent density functional theory (TD-DFT)) and vibrational spectra properties of AlPc are studied. An X-ray pattern reveals the crystalline structure along the (242) orientation of AlPc organic thin layer. An ultraviolet-visible (UV–Vis) also shows the frequency selective behavior of the device. The absorbance of such layer exhibits a high value within UV range and two consecutive peaks within the visible range. Spin coating is used to make an organic diode based on the Aluminium phthalocyanine (AlPc-Cl) molecule. Under dark and light conditions, electrical characterization of Ag/AlPc/Si/Au is obtained. The diode’s high rectifying capability (about $1\times 10^4)$ is subsequently discovered. While the height barrier is constant and saturation current is greatly reliant on light, the ideality factor of such a diode increases to 6.9 which confirms the nonideality of such a device. The Cheung–Cheung technique is employed to further the investigation and gain additional data such as series resistance and barrier height.

It becomes an interesting part for the researchers to analyze the dynamical behavior of soliton propagation in optical fibers for trans-oceanic and trans-continental distances. In this paper, we desire to retrieve distinct and innovative accurate wave solutions to the dual core optical fiber nonlinear equations by adopting the improved tanh method and the rational $(G^{\prime }∕G)$-expansion method. Consequently, a bundle of accurate wave solutions is achieved in diverse sense. The acquired solutions are made visible in the profiles of three-dimensional (3D), two-dimensional (2D) and contour shapes. The effects of the wave speed in soliton transmission are highlighted by plotting different 2D outlines in a single diagram for some obtained solutions. The employed techniques perform as before to unravel the suggested governing models for appropriate wave solutions and hence deserve to contribute in further research.

In this paper, we study one-dimensional discrete solitons in zigzag waveguide arrays with competitive cubic-quintic nonlinearity and competitive linear mixing between the nearest-neighbor (NN) and next-nearest-neighbor (NNN) couplings. The competitive nonlinearity features a cubic self-focusing associated with a quintic self-defocusing nonlinearities. The competitive linear mixing between the NN and NNN couplings is induced by making the two coefficients opposite of each other, which is assumed to be induced by the embedding synthetic gauge phase within the coupling constants. The combination of these two types of competition, linear mixing and nonlinearity can create four types of soliton: multipeak bell-shaped solitons, multipeak flat-top solitons, staggered bell-shaped solitons, and staggered flat-top solitons. The stability and dynamics of these types of solitons are verified systematically through the paper. The total power and the types of competition between the linear mixing play important roles in tuning these solitons.

This paper is focused with the investigation of new exact analytical solutions to two types of nonlinearities of the Lakshmanan–Porsezian–Daniel models, namely anti-cubic law and cubic-quintic law of nonlinearity. To achieve the diverse wave patterns to the considered model, a novel method, namely the new Kudryashov technique, is used. The newly accomplished solutions exhibit many types of wave solutions such as one-soliton, bright, dark, bell-shape and anti-bell shape solutions. The dynamics of the derived solutions are represented by three-dimensional (3D) and two-dimensional (2D) graphs. The novel aspect of this study is the balance between dispersion and nonlinear phenomena, which have not been achieved in previous studies. Based on these solutions, the fiber structure can be designed to improve its quality. Furthermore, this shows the method’s ability to solve various forms of nonlinear complex phenomena and produce other solitary wave solutions.