Value Of Nonlinear Coefficient Research Articles

Advanced frequency of thick FGM cylindrical shells with fully homogeneous equation

The effects of shear deformation theory and improved shear correction factors on the advanced computation of frequencies by using the fully homogeneous equation for thick functionally graded material (FGM) circular cylindrical shells are studied. It is quite reasonable to consider the extra advanced effect of third-order shear deformation theory (TSDT) of displacements on the varied shear correction coefficient. The values of advanced nonlinear shear correction coefficient are usually functions of the nonlinear coefficient term in TSDT, power-law exponent parameter, and environment temperature. The main achievements in the nonlinear case of displacements and with the varied value of shear correction coefficients, the non-dimensional fundamental frequencies are estimated, investigated, and compared with the values in the linear case. This paper aims to study the fundamental frequencies of very thick FGM cylindrical shells under the advanced effects of shear deformation theory and improved shear correction factors.

Design and simulation of photonic crystal fiber for highly sensitive chemical sensing applications

Abstract Photonic crystal fibers (PCF) have demonstrated promising capabilities for liquid sensing applications owing to their distinctive optical properties. This work presents a numerical investigation of a PCF sensor optimized for discriminating water, ethanol, and benzene samples. In the proposed configuration, there are five concentric rings of air holes in the cladding arranged in a hybrid lattice structure, while the core contains only one air hole. The optical properties of the sensor, such as refractive index, power fraction, relative sensitivity, confinement loss, effective area, and nonlinearity, were assessed through a comprehensive analysis utilizing the full vector Finite Element Method within the COMSOL Multiphysics software. All these properties have been meticulously examined through numerical investigation across a broader range of wavelengths spanning from 0.8 to 2.2 µm. The suggested model has high sensitivity, minimal confinement loss, and an exceptional nonlinear coefficient value. At a wavelength of 1.3 µm, the suggested PCF exhibits greater sensitivity of 96.84, 98.12, and 100% for water, ethanol, and benzene, respectively, and nonlinear coefficients of 13.98 W−1 km−1 for water, 13.93 W−1 km−1 for ethanol, and 14.85 W−1 km−1 for benzene, with decreased confinement loss. The created model can be utilized in several research areas, particularly in chemical sensing and bio-sensing, as well as their respective applications.

Advanced Frequency Study of Thick FGM Cylindrical Shells by Using TSDT and Nonlinear Shear

For the advanced frequency study of thick functionally graded material (FGM) circular cylindrical shells, it is interesting to consider the extra effects of nonlinear coefficient term in third-order shear deformation theory (TSDT) of displacements on the calculation of varied shear correction coefficient. The formulation for the advanced nonlinear shear correction coefficient are based on the energy equivalence principle. The values of nonlinear shear correction coefficient are usually functions of nonlinear coefficient term of TSDT, power-law exponent parameter and environment temperature. The free vibration frequencies of thick FGM circular cylindrical shells are investigated with the simply homogeneous equation by considering that simultaneous effects of the TSDT, the nonlinear shear correction coefficient of transverse shear force and the two direction of mode shapes. The novelty is more important and reasonable for the thick FGM circular cylindrical shells, especially for the ratio of length to thickness is five by considering the effects of advanced nonlinear shear correction coefficient and nonlinear coefficient term of TSDT on the advanced calculation of fundamental first natural frequencies.

Ultrafast optical characteristics of Mn-doped CdS quantum dots

Cadmium sulfide (CdS) quantum dots (QDs) doped with different concentrations of manganese (Mn = 0, 1, 3, 5, and 7 %) are synthesized via thermolysis of diselenocarbamato complexes of cadmium in the trioctylphosphine oxide (TOPO). The QDs show quantum size effects in the optical spectra and exhibit band-edge emission. The TEM images revealed that the QDs are spherical within the range of 3 to 5 nm. The nonlinear optical studies and optical limiting characteristics are studied. From open and closed aperture data, the nonlinear absorption coefficient (β) and refractive indices (n2) values are found to be in the range of 4–16 x10-9 cm2/w and 8-14x10-15 cm2/w. The cross relaxations and energy transfer mechanism of quantum dots are studied using the transient absorption pump–probe experiment.

Nonlinearity of mechanical behavior of 3D-reinforced composites under compression

Modern technological capabilities make it possible to produce 3D spatially-reinforced for polymer composite materials. The tasks of experimental research and analysis of the deformation process of new composite materials for aviation purposes taking into account the nonlinearity of mechanical behavior become actual. The paper presents an experimental study of the mechanical compression behavior of composite material specimens made of 3D woven carbon fiber preforms using the pressure impregnation technology (Resin Transfer Molding method with a pairwise interlayer reinforcement and a longitudinal layer). Compression mechanical tests were carried out on specimens using a universal system of electromechanical testing Instron 5882 and a system of 3D analysis of displacement and strain fields on the surface. Tests were conducted in accordance with ASTM D 3410 recommendations and using specialized tooling. Consideration of nonlinearity parameter during experimental data processing is proposed. The importance of determining the values of critical deformation in compression as a parameter characterizing the moment of the beginning of fracture is noted. Comparison of carbon fiber composite materials made by the same technology from fibers and binders of different manufacturers has been carried out. The experimental diagrams "stress-strain" and their approximating dependences taking into account the nonlinearity function w are obtained. The type of functions w of the studied materials is defined, the linear approximation of dependence of functions w on deformation is substantiated. Values of strength limits, elastic modulus, nonlinearity coefficient and critical damage were obtained, statistical processing of the obtained results and their analysis were carried out.

Chitosan, a Cationic Polymer-Loaded CuS:Ni Nanoparticles Well Suited for Pseudocapacitors, Optical Switching and Spintronic Devices

Chitosan, a cationic polymer, is loaded on Ni-doped copper monosulfide (CuS) NPs with optimal Ni doping concentration, and electrochemical, third-order nonlinear, magnetic and antibacterial characteristics of chitosan unloaded and loaded CuS:Ni nanoparticles are compared. The crystallite size of pure CuS increased with Ni doping and the 10[Formula: see text]wt.% Ni-doped CuS NPs exhibit a maximum crystallite size of 41[Formula: see text]nm. The presence of Ni in the doped samples was acknowledged by the existence of Ni 2p[Formula: see text] and Ni 2p[Formula: see text] peaks at binding energies 851[Formula: see text]eV and 873.1[Formula: see text]eV, respectively from the XPS spectrum. Optical reflectance decreased with Ni doping and the optical band gap varied from 2.56[Formula: see text]eV to 2.4[Formula: see text]eV. Specific capacitance increased with Ni doping. Diamagnetic nature of CuS changed to ferromagnetic with Ni doping. The 10[Formula: see text]wt.% Ni-doped CuS exhibits a high third-order nonlinear absorption coefficient and susceptibility value. Bacterial growth inhibition nature of CuS improved with Ni doping. Among the doped samples, the 10[Formula: see text]wt.% Ni-doped sample exhibits improved electrochemical, third-order nonlinear, magnetic and antibacterial properties. Keeping this as the optimized Ni concentration, chitosan was loaded. Chitosan-loaded samples exhibited a reduction in crystallite size and an increase in band gap. A high specific capacitance of 96[Formula: see text]F/g was realized for the chitosan-loaded sample. Saturation magnetization of 10[Formula: see text]wt.% CuS:Ni decreased with chitosan loading.

Synthesis and characterization of linear/nonlinear optical properties of graphene oxide and reduced graphene oxide-based zinc oxide nanocomposite

In this paper, we aimed to investigate the linear and nonlinear optical properties of GO-ZnO and RGO-ZnO nanocomposites in comparison with pure GO and reduced graphene oxide (RGO). For this purpose, GO, RGO, GO-ZnO, and RGO-ZnO were synthesized and characterized by Fourier transform infrared (FT-IR), Ultraviolet–Visible (UV–Vis) absorption, X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). XRD and EDX analysis indicated the reduction of GO as well as the successful synthesis of GO-ZnO and RGO-ZnO nanocomposites. The FT-IR spectroscopy showed that absorption bands were at 3340 cm−1, 1630 cm−1, 1730 cm−1 and 480 cm−1 related to OH, C=C, C=O, and Zn–O stretching vibrations, respectively. The direct band gaps of GO, RGO, GO-ZnO and RGO-ZnO from UV–Vis spectra were at 3.36, 3.18, 3.63 and 3.25 eV, sequentially. Moreover, the third-order nonlinear optical properties were investigated using a z-scan technique with Nd: YAG laser (532 nm, 70 mW). It can be seen that the nonlinear absorption coefficient value (upbeta ) increased from 5.3 × 10–4 (GO) to 8.4 × 10–3 cm/W (RGO-ZnO). In addition, nonlinear refractive index (n2) of the GO, RGO, GO-ZnO, and RGO-ZnO was obtained as 10.9 × 10–10, 14.3 × 10–10, 22.9 × 10–10, and 31.9 × 10–10 cm2/W respectively.

The Kurtz-Perry Powder Technique Revisited: A Study of the Effect of Reference Selection on Powder Second-Harmonic Generation Response.

The accurate evaluation of nonlinear optical (NLO) coefficient, the main parameter affecting light conversion efficiency, plays a crucial role in the development of NLO materials. The Kurtz-Perry powder technique can evaluate second-harmonic generation (SHG) intensity in pristine powder form, saving a significant amount of time and energy in the preliminary screening of materials. However, the Kurtz-Perry method has recently been subject to some controversy due to the limitations of the Kurtz-Perry theory and the oversimplified experimental operation. Therefore, it is very meaningful to revisit and develop the Kurtz-Perry technique. In this work, on the basis of introducing the light scattering effect into the original Kurtz-Perry theory, the theoretical expression of second-harmonic generation intensity with respect to band gap and refractive index are analyzed. In addition, the reference-dependent SHG measurements were carried out on polycrystalline LiB3O5 (LBO), AgGaQ2 (Q = S, Se), BaGa4Q7 (Q = S, Se), and ZnGeP2 (ZGP), and the results of SHG response emphasize the importance of using appropriate references to the Kurtz-Perry method. In order to obtain reliable values of nonlinear coefficients, two criteria for selecting a reference compound were proposed: (1) it should possess a band gap close to that of the sample to be measured and (2) it should possess a refractive index close to that of the sample to be measured. This work might shed light on improvements in accuracy that can be made for effective NLO coefficients obtained using the Kurtz-Perry method.

Effect of Ba/Sr ratio on the nonlinear optical properties of Ba1-xSrxTiO3 (x = 0.1–0.9) thin films

Perovskite-structured barium strontium titanate (Ba1-xSrxTiO3, x = 0.1–0.9) films have been epitaxially fabricated by using a pulsed-laser deposition technique. The third-order nonlinear optical properties were studied through a z-scan method, allowing the resolution of the nonlinear refractive and absorptive contributions to the responses. Although all the samples show almost the same value of nonlinear absorption coefficient, the extracted nonlinear refractive index of the sample of x = 0.3 is apparently larger than that of other samples. Dependency of the nonlinear optical properties on the Ba/Sr ratio is discussed in terms of the crystal phase transformation and metal-oxygen bond length of the selected materials.

Giant dielectric response, nonlinear characteristics, and humidity sensing properties of a novel perovskite: Na1/3Sr1/3Tb1/3Cu3Ti4O12.

In this study, we unveil a novel perovskite compound, Na1/3Sr1/3Tb1/3Cu3Ti4O12, synthesized through a solid-state reaction method, exhibiting remarkable giant dielectric response, nonlinear characteristics, and humidity sensing capabilities. This research highlights the emergence of a Cu-rich phase, the properties of which undergo significant alterations depending on the sintering conditions. The optimization of sintering parameters, encompassing a temperature range of 1040-1450 °C for 1-8 h, resulted in substantial dielectric permittivity (ε') values (∼2800-6000). The temperature dependence of ε' demonstrated relationship to the particular sintering conditions utilized. The acquired loss tangent values were situated within encouraging values, ranging from 0.06 to 0.16 at 1 kHz. Furthermore, the material revealed distinct nonlinear electrical characteristics at 25 °C, with the nonlinear coefficient values of 5-127, depending on ceramic microstructures. Additionally, we delved deeply into the humidity-sensing properties of the Na1/3Sr1/3Tb1/3Cu3Ti4O12 material, showing a considerable variation in ε' in response to fluctuations in relative humidity, thereby indicating its prospective application in humidity sensing technologies. The hysteresis error and response/recovery times were calculated, highlighting the versatility of this compound and its promising potential across multiple applications. The Na1/3Sr1/3Tb1/3Cu3Ti4O12 not only shows remarkable giant dielectric responses but also portrays significant promise for nonlinear and humidity sensing applications, marking it as a significant participant in the advancement of perovskite-based functional materials.

Influence of nitro group on solvatochromism, nonlinear optical properties of 3-morpholinobenzanthrone: Experimental and theoretical study

We report the synthesis of 3-morpholino-9-nitrobenzanthrone (NMB) dye. By using FT-IR, 1H NMR, and X-ray crystallography, we characterized the molecular structure of the synthesized dye. The structural features of the dye were compared to those of an identical dye without nitro substituents. The push pull kind of benzanthrone dye (NMB) was examined for solvent-dependent photophysical properties. NMB exhibits a large Stokes shift. The polarity plots indicate that hydrogen-bonding interactions are influential in most of the solvents. Detailed structural analysis as well as one-photon absorption and emission process was computationally investigated for both the molecules. NMB exhibits significant two photon absorption (TPA) activity at various electron transitions ranging from visible to NIR regions. Further, Nonlinear absorption coefficient was calculated for the dye samples from the open aperture Z-scan data. The nonlinear absorption coefficient values were obtained for the dye samples for input laser pulse energies ranging from 5 to 20 µJ. The results decipher that these dye samples are prospective contenders for the fabrication of optical limiter devices. Nitro substituents at the active site enhance charge transfer, thereby enhancing the NLO response.

Nonlinear optical properties and broadband ultrafast photonics application of 2D-zirconium tritelluride (ZrTe3)

Two-dimensional (2D) transition metal chalcogenides (TMCs) have lately attracted broad interest in advanced photonics field due to their tunable bandgap, high broadband absorption, and excellent nonlinear optical (NLO) performances. Among other TMCs, group-IV transition metal trichalcogenides (TMTs) are rarely investigated for the NLO applications. Zirconium tritelluride (ZrTe3) is a kind of group-IV TMTs that shows metallic behavior among TMTs materials. While several electrical properties of ZrTe3 have been studied recently, the research community is longing to explore NLO features of ZrTe3. Herein, by using open aperture Z-scan method, the NLO properties of ZrTe3-nanosheets are investigated. The admirable NLO characteristics of ZrTe3 are realized from the obtained highest nonlinear absorption coefficient value of −82.1 × 103 in 1 µm and −13.05 × 103 cm/GW in 1.5 µm. Moreover, broadband fiber optics ZrTe3-based saturable absorbers (SAs) are prepared for the first time by depositing 2D-ZrTe3 nanosheets on a side-polished fiber. Following integration of these ZrTe3-SAs into three distinct rare earth-doped fiber laser cavities, stable mode-locking pulses with pulse widths of 323 ps (1 µm), 751 fs (1.5 µm), and 1.2 ps (2 µm) are obtained, respectively. These findings indicate that the ZrTe3 can facilitate the exploration of 2D materials in nonlinear optics and ultrafast photonics applications.

Defect assisted enhanced nonlinear optical performance and optical limiting of pure and doped BiVO4 powders and nanocomposite films

The linear and nonlinear absorption properties, photoluminescence and optical limiting properties of bismuth vanadate (BiVO4) powders and films were presented in this work. The structural, morphological and optical effects of different doping elements (M: Mo,W and Ni) were investigated (M: BiVO4). XRD and Raman results proved that BiVO4 and M: BiVO4 powders were synthesized in the monoclinic scheelite structure. Twhe powder morphology as found to be changed by Ni and W doping. The nonlinear optical responses of pure and M: BiVO4 were studied using the open aperture Z-scan experiment and a theoretical model was used to determine the nonlinear optical absorption performance. The nonlinear absorption coefficient (βeff) values were found to be 6.59 × 104, 8.86 × 104, 2.26 × 105 and 1.62 × 106 cm/GW for BiVO4, Mo: BiVO4, W: BiVO4 and Ni: BiVO4 nanocomposite films, respectively. The highest nonlinear absorption coefficients (βeff) and saturation intensity thresholds (ISAT) were obtained for Ni:BiVO4 film. Experimental results showed that the βeff value and band gap can be controlled by the dopant element, making doped BiVO4 a good candidate for nonlinear optical applications such as optical limiters, optical switches and modulators in integrated photonic devices.

Generation of high-frequency pulse train by designing a buried SOI waveguide

Silicon photonics has attracted tremendous research interest in recent times because of its compact size, easy-to-build nature, and high values of nonlinearity. Though the study of pulse interaction inside a planer SOI waveguide is done earlier, the confinement of light should be better in the case of a buried core waveguide. Such a buried rectangular SOI waveguide is designed here, which possesses a small value of group velocity dispersion (β2) ∼2.432 (ps2/m) and a quite high value of nonlinear coefficient (γ) of ∼ 441.19 (W.m)−1. When the propagation of a pair of pulses of lower repetition rate (∼GHz) is investigated through it, we have found that the pulse pair interact with each other as they overlap and generate a high-frequency (∼THz) pulse train. The effect of timing jitter on high-frequency generation is also studied. The study of interactions of pulse pairs inside an SOI waveguide helps us to explore the potential applications of such devices as tunable high frequency (THz) pulse generators and many more.

Controllable low-temperature flash sintering and giant dielectric performance of (Zn, Ta) co-doped TiO2 ceramics

In this study, the challenge of high-temperature and long-time sintering of (Zn, Ta) co-doped TiO 2 ceramics is solved successfully using flash sintering technology. Joule heating and a high heating rate make the sample compact rapidly at low temperatures (1050 °C in 24 min). When the electric field was equal to 200 V/cm, high permittivity (ε' ∼ 1.32 × 10 4 ), low dielectric loss tangent (tan δ ∼ 0.27), and nonlinear coefficient ( α ∼ 5.8) values were obtained. Flash sintered samples have more free electrons, resulting in a high dielectric constant. Further, the higher the electric field, the smaller the grain resistance of the sample; this condition is conducive to reducing dielectric loss. giant dielectric performance is explained by the combined action of the electron-pinned defect dipole theory and the internal barrier layer capacitance effect. Therefore, this study provides a promising prospect for the green preparation of co-doped TiO 2 giant dielectric ceramics.

Nonlinear optical properties of lithium niobate crystals doped with alkaline earth and rare earth elements

Nonlinear optical properties of lithium niobate crystals doped with alkaline-earth (Zn2+) and rare-earth (Er3+) elements were quantitatively studied from the chemical bond viewpoint of crystal. The different influences of Zn and Er dopants on the dielectric response of LiNbO3 were compared. The value of nonlinear optical second-harmonic generation coefficients was determined mainly by the Li–O bonds both in LiNbO3:Zn and LiNbO3:Er crystals. We observed sharp changes in the second order nonlinear optical response of Zn-doped LiNbO3 single crystals at 1064 nm with increasing Zn concentration in the crystal. The calculated values of the nonlinear optical coefficients for the LiNbO3:Zn crystals exceed those for the LiNbO3:Er crystals. The LiNbO3:Zn crystal with dopant concentration 5.48 mol.% is the most suitable crystal for the second-harmonic conversion.

Investigating the effects of intermolecular interactions on nonlinear optical properties of binary mixtures with high repetition rate femtosecond laser pulses

Measurements of nonlinear optical (NLO) properties of different binary mixtures having carbon disulfide (CS2) as the common component, namely CS2-acetone, CS2-cyclopentanone, CS2-toluene, and CS2-carbon tetrachloride (CCl4), are carried out by using the z-scan technique. Open-aperture z-scan (OAZS) and close-aperture z-scan (CAZS) experiments are performed to determine the nonlinear absorption coefficient (β) and nonlinear refractive index (n2) of all binary liquid mixtures at various compositions of the components by employing a pulsed, high repetition rate (HRR) femtosecond laser. Also, we were able to use the flowing liquid to measure NLO properties in the CS2-acetone binary mixture to remove the cumulative thermal effects produced due to the pulsed HRR laser light. Nonlinear refractive index (n2) values are found to be influenced by the weak dipole-induced dipole intermolecular interactions between the nonpolar CS2 and polar acetone as well as cyclopentanone of the respective binary mixtures. On the contrary n2 values are not found to be affected by the intermolecular interactions in CS2-toluene and CS2-CCl4 binary mixtures. In comparison, the nonlinear absorption coefficient (β) values are not found to be affected by the same in all different sets of binary mixtures.

Femtosecond Z-scan measurement of third-order nonlinear optical response of fluorine-doped tin oxide

The excitation wavelength dependent nonlinear optical response of fluorine-doped tin oxide (FTO) is systematically studied by the Z-scan technique. The broadband third-order nonlinear optical properties of FTO are verified and a value of nonlinear refractive index coefficient n 2 to be 2.52 × 10−16 m2 W−1 is obtained at epsilon-near-zero region. Meanwhile, a large modulation depth and nonlinear absorption coefficient β are estimated about 9.61% and −1.96 × 10−9 m W−1, respectively. The experimental results indicate that FTO is a promising nonlinear optical material and has great application potential in the field of nonlinear optical devices.

Synthesis and characterization of ZnO based varistor ceramics: effect of sintering temperatures

PurposeThe purpose of this paper is to investigate the effects of the sintering temperature on the microstructural, morphological and electrical characteristics of Zinc oxide (ZnO)-based varistors.Design/methodology/approachThis study used a conventional method to design and produce ZnO varistors by sintering ZnO powder with small amounts of various metal oxides. Furthermore, the effect of sintering temperature on varistor properties of (Bi, Co, Cr, Sb, Mn)-doped ZnO ceramics was investigated in the range of 1280–1350 °C.FindingsThe obtained results showed an EB value of 2109.79 V/cm, a Vgb value of 0.831 V and a nonlinear coefficient (α) value of 19.91 for sample sintered at temperature of 1300 °C. In addition, the low value of tan δ at low frequency range confirmed that the grain boundaries created in 1300 °C sintering temperature were obviously good.Originality/valueBased on the previous research on the ZnO-based varistors, a thorough study was carried out on these components to improve their electrical characteristics. Thus, it is necessary that those varistors have low leakage current and low value of dissipation factor to ensure their good quality. High breakdown fields and nonlinearity coefficients are also required in such kind of components. The effect of sintering temperature on the varistor properties of the new compositions (zinc, bismuth, manganese, chrome, cobalt, antimony and silicon oxides)-doped ZnO ceramics was studied in the range of 1280–1350 °C. Also, the microstructure and the phase evolution of the samples sintered at various temperatures (1280 °C, 1300 °C, 1320 °C and 1350 °C) were investigated according to X-ray diffraction and scanning electron microscope measurements.

A comprehensive study of large negative dispersion and highly nonlinear perforated core PCF: theoretical insight

A photonic crystal fiber (PCF) containing circularly organized square-shaped air holes in the cladding region is investigated. The fiber core is perforated with four circular air-filled holes to instate high nonlinearity and large negative dispersion. The numerical analysis is done with a finite element method based COMSOL Multiphysics tool to investigate different optical properties of the propounded PCF. The simulation outcome verifies a high nonlinear coefficient value of 85 W−1 Km−1 at telecommunication window 1.55 μm which is, the highest ever achieved value on comparing with the other existing literature without using any nonlinear materials or liquids to the best of the authors’ knowledge. In parallel, the large negative value of dispersion −597 ps nm−1 km−1 is achieved for S/Λ equals 0.70 at the same communication window. However, the highest achieved nonlinearity and negative dispersion are 300 W−1 Km−1 and −1689 ps/nm/km. Moreover, birefringence, numerical aperture, and propagation loss are also measured as 2.40 × 10−3, 0.59, and 4.12 × 10−11 dB m−1 respectively along with an extremely high core power fraction of 99.98%. Hence, the propounded PCF is suitable for residual dispersion compensation, supercontinuum generation, and high bitrate transmission.