Journal of Nonlinear Optical Physics & Materials

In this study, we report photonic band structures and optical transmissions of some SiC polytypes, such as 3C, 2H, 4H, and 6H, and their multilayers, which have the form of a hexagonal photonic crystal at two-dimensional (2D) scale. Through the finite-difference time-domain computational simulations, we found that spatial electric-field variations of electromagnetic waves depend on the radius of dielectric rods of the multilayer crystal structure, and the central structural geometry of 4H- and 6H-SiC hexagonal polytypes was found to cause a remarkable increase of the wave vector $k$ in $x$ and $y$ directions. We also found a correlation between the local central structures of the optical modes in the 2D hexagonal crystal of 4H- and 6H-SiC polytypes. The wave-guiding in 4H- and 6H-SiC polytypes in the central core of the model geometry enabled the integration of defects to achieve a wide spectrum of technological functionalities, such as devices with striking features for miniaturized sensors and quantum information processing.

In the this study, we focus on the growth of a metal-organic creatininium borate (CRB) single crystal for third-order nonlinear optical (NLO) applications. Optically transparent & wide optical band gap single crystals of CRB were successfully harvested by adopting a slow evaporation solution technique (SEST) at a constant 40${}^{\circ }$C temperature. The structural identification and lattice parameters of the grown sample were determined by powder X-ray diffraction (PXRD) using Rietveld analysis by FullProf Suite software. The occurrence of vacancy/interstitial defects produced during growth was investigated by high-resolution X-ray diffraction (HRXRD) using omega scan arrangement. A single peak with lower full width half maxima (56.4 arc s) was obtained from the scan which suggests that there were no grain boundaries for the grown crystal. Surface morphology and its features such as concentration of dislocations and defect sites on the as-grown sample were scrutinized using the etching technique. The optical band gap and UV–vis cut-off were examined and found to be 5.39 eV and 230 nm, respectively. Photoluminescence characteristics of the crystal show an emission at 377 nm upon excitation with a wavelength of 336 nm. The presence of radiative and non-radiative transitions inside the crystal due to excitation upon 266 nm laser was identified using time-resolved photoluminescence. Thermal stability and decomposition temperature of the compound were obtained by thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The third-order nonlinearity of the crystal was determined by Z-scan measurement technique with a femtosecond Ti-sapphire laser.

The breather, rogue and interaction waves of the (3+1)-dimensional integrable fourth-order nonlinear equation are reviewed. The breather and rouge waves are attained with the aid of the extended homoclinic test. Thereafter, the interaction solutions between a lump wave and a 1-kink or 2-kink soliton are researched. Additionally, four kinds of interaction solutions between lump, kink, and periodic waves through a “rational-cosh-cos” test function are established. Furthermore, the dynamic attributions of the attained solutions are presented utilizing the graphical analysis.

Nanoscale optical fibers, capable of confining light at the nanoscale, exhibit nonlinear effects and generate a strong evanescent field interacting with the surrounding environment. In this study, we compared various nanofibers composed of different glasses, closely matching the refractive index of silica, while immersed in acetone. Our objective was to optimize the Kerr effect contributions from either the core or the cladding, dependent on factors such as nanofiber dimensions, core optical properties, and the effective area of the fundamental mode HE${}_{11}$ both inside and outside the nanofiber core. Our findings reveal that the fluorophosphate (S-FPM3) nanofiber exhibits a dominant Kerr effect when immersed in acetone compared to the silica nanofiber. Specifically, for a radius $r=200$nm, the S-FPM3 nanofiber core demonstrates a Kerr coefficient ${\gamma }_{\mathrm{\text{co}}}=1{\mathrm{\text{m}}}^{-1}{\mathrm{\text{W}}}^{-1}$, three times higher than that of the silica nanofiber. Similarly, for $r=150\mathrm{\text{nm}}$, the Kerr coefficient ${\gamma }_{\mathrm{\text{cl}}}=2.3{\mathrm{\text{m}}}^{-1}{\mathrm{\text{W}}}^{-1}$ for the S-FPM3 nanofiber cladding is three times greater than that of the silica nanofiber, despite both having nearly identical nonlinear indices. Additionally, we observed that Kerr coefficients follow similar variations across different wavelengths in the visible and infrared regions, with values decreasing significantly due to the inverse proportionality with optical wavelength $\lambda$. Analyzing the dynamics of nanofiber normalized diameter reveals a sub-wavelength threshold optimizing effective nonlinearity, particularly in the case of the NC21A nanofiber. These findings suggest the potential use of optical nanofibers as reliable sensors in challenging-to-access areas for external media and the enhancement of nonlinear effects through the evanescent field.

The simultaneous detection of a mixture of two gases with the aid of unique and excellent capabilities of anti-resonance hollow-core fibers (AR-HCF), is numerically investigated in this article. Low-loss transmission bands in near and mid-infrared, which correspond to the transition of methane (CH${}_4)$ and carbon dioxide (CO${}_2)$, are considered in this work. Reasonable consideration of structural parameters has caused the low-loss transmission band covering 1.57 $\mu$m and 3.33 $\mu$m wavelengths. The second harmonics caused by the interaction of the laser beam and the gas sample inside the hollow core of the fiber were analyzed utilizing the fast Fourier transform (FFT) method. The maximum amplitude for the corresponding frequency at the determined concentration has reached 3002 ${\mathrm{\text{cm}}}^{-1}$ for CH₄ and 6381 ${\mathrm{\text{cm}}}^{-1}$ for CO₂. Enhancement of the inhibited coupling between the fundamental mode and some of the cladding modes and leakage loss reduction, extra capillary tubes nested inside the silica tubes forming the fiber cladding. The simulation results confirm the suitability of the proposed structure for efficient utilization in gas sensing applications for two different spectral ranges in the near and mid-infrared. Benefiting from a large hollow core, very low background noise and anti-resonance properties, high sensitivity of about 99.6% and confinement loss of 0.127 dB/m were obtained.

2-methylimidazole (2MI) single crystal has been successfully grown by slow evaporation solution technique (SEST) by using water as a solvent. The synthesized 2MI crystal was purified by repetitive recrystallization. Various other characterizations were carried out for the grown 2MI single crystal, such as powder X-ray diffraction (PXRD), FTIR, UV–Visible NIR, Microhardness, Photoluminescence, SEM, Piezoelectric, and SHG. The 2MI crystal was subjected to PXRD to endorse the crystalline quality of the material. The vibrational assignments and their functional groups were identified from the FTIR analysis. The UV–Visible NIR study exposes the transparency and cut-off wavelength of the 2MI crystal. The mechanical strength was investigated by Vickers microhardness tester. The surface investigation of the 2MI crystal was analyzed by a scanning electron microscope technique to obtain the presence of defects and surface texture in the developed 2MI crystal. The photoluminescence spectrum confirmed the green light emission of the crystal. The value of the piezoelectric d${}_{33}$ coefficient is measured using piezoelectric analysis. Kurtz powder’s second harmonic generation test reveals that the frequency conversion efficiency of 2MI is 3.7 times higher than that of potassium dihydrogen phosphate (KDP) crystal.

Potent ocular materials with noncentrosymmetric frameworks seek the attention of researchers throughout the globe. A polymorph of 2,4-dinitrophenylhydrazine single crystals with such framework was grown by slow cooling mechanism with 1,4-dioxane as the solvent. The noncentrosymmetric characteristics of the grown material were confirmed by using X-ray diffraction analysis. The presence of functional groups of the title meld was identified with the aid of Fourier transform infrared spectroscopy analysis. The ability of the material to withstand temperature with weight loss and decomposition peak was determined by using TG/DTA analysis. The transmission window and optical bandgap of the materials were determined by using UV–Vis analysis. The nonlinear optical behavior of the grown crystals was determined with the aid of SHG and Z-scan analysis. The computational analysis was performed using Gaussian 09 software package to investigate various parameters of title meld. Hirshfeld surface analysis was performed using Crystal explorer 17 to quantify the intermolecular interactions of the grown material.

This work focuses on deriving optical soliton solutions for the stochastic variant of the higher-order Lakshmanan–Porsezian–Daniel (LPD) model, which incorporates cubic-quintic law nonlinearities alongside chromatic and spatio-temporal dispersion terms. The primary approach chosen for this purpose is the new Kudryashov method (nKM). Initially, bright and dark soliton solutions are derived. The stability of these dark and bright solitons is then verified using the Vakhitov–Kolokolov criterion. Subsequently, the impact of the stochastic term on the bright and dark solitons is examined. As an additional aspect, an investigation has been conducted on the effects of the model parameters, namely, group velocity dispersion and spatio-temporal dispersion terms.