Journal of Nonlinear Optical Physics & Materials

This paper reviews the vibrant field of nonlinear optical (NLO) properties of metal oxide nanoparticles and nanocomposites. It includes a historic introduction which discusses the birth and successive developments of NLO. An attempt is made to give a summary in a nutshell about the basic concepts of nonlinear optics and different NLO phenomena with special attention to third-order phenomenon and $Z$-scan technique. The review also touches on the topic of science and technology of metal oxide nanoparticles and nanocomposites, various synthesis processes that include co-precipitation, micro-emulsion, sol–gel route, etc. have been discussed. Metal oxide nanoparticles and nanocomposites are introduced with a deep focus on the origin of various physical mechanisms and optical properties. The origin of NLO properties from these important structures has also been discussed. Some recently studied metal oxide nanocomposites along with their NLO coefficients are also given.

High-quality organic L-histidinium 4-nitrophenolate 4-nitrophenol (LHPP) single crystals were grown using an aqueous solution. The crystals were grown using slow evaporation solution technique (SEST) at a temperature of 40°C using a constant temperature bath (CTB). Nucleation growth rates were monitored for various durations using an optical microscope. The crystalline perfection was confirmed through sharp, high-intensity diffraction peaks observed in the theoretical and experimental powder X-ray diffraction (PXRD) analysis, which also confirmed the monoclinic crystal structure with the noncentrosymmetric P2₁ space group. The crystallite size and strain were calculated using Williamson–Hall coefficient. Vibrational frequency assignments of LHPP were determined using FTIR spectroscopic analysis. Optical properties were studied using UV–Vis NIR spectroscopic studies, which showed that the crystals have very low absorption and high transmittance in the entire visible region. Additionally, the optical energy bandgap (Eg) was calculated and found to be 6.15eV. Luminescence properties were studied using fluorescence (FL) analysis. Dielectric investigations were subjected to varying frequencies to study the suitability of the crystal for transistor application. The positive photoconductive (PC) nature of the crystal was confirmed using photoconductivity studies to confirm suitability for photodetector devices that measure the intensity of light rays. Etching studies revealed the growth pattern and the formation of different kinds of etch pits. The surface morphology was studied using scanning electron microscopy (SEM) and electrochemical studies were also carried out. The relative second harmonic generation (SHG) efficiency of the material was also examined and found to be 1.34 times that of standard KDP. The optical limiting and higher-order nonlinear optical (NLO) properties of the grown crystals were studied by the $Z$-scan method using a Nd: YAG laser functioning at 532nm.

To study the effect of terminal groups substituent on the two-photon absorption (TPA) properties of $D$-$\pi$-$A$-$\pi$-$D$ structural dyes with diketo-pyrrolo-pyrrole (DPP) as central electron acceptor group, linear/transient absorption spectroscopy, one/two-photon fluorescence spectra, open-aperture $Z$-scan, and excited states quantum chemical calculations have been performed to systematically study the intermediate product electron acceptor J0 as well as three $D$-$\pi$-$A$-$\pi$-$D$ structural dyes using benzene, triphenylamine and 2,3-methoxy-triphenylamine as terminal electron donors, named as J1, J2, and J3, respectively. The intermediate product electron acceptor itself exhibits a relatively large TPA response, which indicates the DPP group has a large conjugated system. J2, with strong electron-donating ability groups triphenylamine as terminal groups, shows a large TPA cross-section of 534GM, which is approximately 10 times larger than that of J1 with weak electron pushing/pulling abilities groups benzene as terminal groups (51GM). The result indicates that the electron-donating abilities of terminal groups do play a key role in TPA response. Furthermore, methoxy substituent on the terminal triphenylamine groups can further effectively increase the TPA response, J3 exhibits a 15-fold enhancement compared with that of J1. Transient absorption spectra and quantum chemical calculation results are well accorded with the experimental results. Terminal substituents with strong electron donor groups are beneficial for the formation of intramolecular charge transfer (ICT) process. Besides, methoxy substituent in the terminal of triphenylamine groups can further enhance the degree of ICT and induce AIE characteristics in the molecule.

In this paper, several new optical soliton solutions of the time-fractional generalized resonant nonlinear Schrödinger equation, relevant to pulse propagation in optical fibers, are constructed using the extended simplest equation approach. The new exact solutions are expressed in terms of hyperbolic functions, trigonometric functions, and rational functions. Further, two-dimensional, three-dimensional, and contour graphs of king-type, wave, dark–bright, bright, and bell-shaped optical soliton solutions are plotted to elucidate the significance of the time-fractional generalized resonant nonlinear Schrödinger equation using appropriate values of physical parameters. The dynamic behavior of the present solutions, incorporating the effect of the conformable fractional derivative, is depicted through two-dimensional graphs. The derived optical solutions are considered novel and have presumably not been previously reported in the literature.

In this study, the effects of introducing a zinc cation into a zinc-phthalocyanine (ZnPc) cluster are examined in relation to organic phthalocyanine material. The Au/ZnPc/Si-based organic diode is made using the thermal evaporation method. The optical properties of the filter are checked and a selected wavelength of 360nm is recorded. Au/ZnPc/Si/Al exhibits high rectifying performance, and the organic device’s primary conduction mechanism is Space Charge Limited Current. ZnPc film’s superior transparency is shown in the visible spectrum, and its optical bandgap of 3.32eV is found. According to this result, ZnPc is a semiconductor. ZnPc has a weak exciton binding energy (600meV), a high chemical stability, and non-zero value of second hyperpolarizability (4.7310${}^{-36}$esu). These features can offer our ZnPc-based organic device a wide range of applications, including microelectronics, solar cells, and nonlinear optical devices.

Periodically poled thin film lithium niobate waveguide-based supercontinuum generation was measured to be sensitively dependent on input polarization orientation, which has not been much explored. Experimentally more than two octaves supercontinuum was generated, and the effects of pump power and polarization on supercontinuum generation, second harmonic generation and short-wavelength dispersive wave were mapped from 450–1,750nm. Specifically, we identify parameters for the simultaneous second-harmonic and dispersive wave generation near 780nm and 1,000nm, which allows for the $f_{\mathrm{\text{CEO}}}$ detection, and shows promises for the optical atomic clock and optical frequency referencing.

In this paper, we investigated the scattering behavior of solitons in nonlocal, nonlinear Kerr media with inhomogeneous defects by combining a variational approach with numerical simulations. Our extensive numerical simulations confirm the predictions made using the variational approach and demonstrate the robustness of the analytical model, allowing further exploration of soliton dynamics in complex media. The model correctly considers the key physics of defect–soliton interactions and exposes the conditions under which soliton trapping, reflection and transmission can be controlled for applications such as optical data processing and information transmission. Our results provide a new, in-depth understanding of soliton dynamics in general.

In this paper, we experimentally demonstrate the dual pulse emissions of conventional soliton (CS) and noise-like pulse (NLP) in thulium-holmium co-doped fiber laser using tungsten trioxide saturable absorber (WO₃-SA). The CS pulse delivered 2ps width, centered at 1982.8nm. Increasing the pump power and alteration of polarization states switched the CS to the NLP regime with 1990.0nm central wavelength, 17.2nm spectral bandwidth, and 396fs spike width riding on top of a wide picosecond pulse pedestal in the time domain. This work suggests the capability of WO₃-SA as a pulse initiator for future dual-source ultrashort pulses based on an all-fiber laser cavity design.