Journal of Nonlinear Optical Physics & Materials

With the advancement of near-infrared laser technology, there is a significantly increased possibility of exposure of the human eye and optical devices to intense laser conditions. Consequently, research on protection against near-infrared lasers is becoming increasingly prevalent. This review has provided an overview of the recent advancements in the field of nonlinear optical materials, focusing on materials such as graphene, carbon nanotubes, inorganic metal clusters, transition metal sulfides, perovskites and copper niobate. These materials exhibit promising performance in near-infrared optical limiting applications, showcasing good broadband capabilities, but still face urgent issues in terms of structural control, performance regulation, high-purity preparation, and device applications.

A detailed theoretical analysis of ultrafast intensity-dependent Saturable Absorption (SA) to Reverse Saturable Absorption (RSA) transition in CoTCPP SURMOF nanofilms has been presented with femtosecond (fs) laser pulses at 400nm. The effect of input pulse intensity, sample thickness, concentration, and 3${}^{\mathrm{\text{rd}}}$ and 5${}^{\mathrm{\text{th}}}$ order nonlinear absorption (NLA) coefficients on transmittance has been studied in detail and optimized for high contrast and low-power operation. The maximum modulation achieved for RSA is 55% at 62GW/cm². The results have been used to design all-optical fs-NOT, AND, OR, XOR and the universal NOR and NAND logic gates with 400nm thick CoTCPP SURMOF nanofilms. The modulation achieved for all-optical universal NAND logic gate is 45% at $I_o=55$GW/cm². All-optical encryption and decryption for information security has been demonstrated based on all-optical XOR logic gates which offers high bit rate of 9Tbits/s at $I_o=55$GW/cm² for secure data transmission without any optoelectronic conversion delays. An all-optical passive diode has also been theoretically designed with 17dB nonreciprocity. Ultrafast operation at relatively low input intensities opens up interesting prospects for the applicability of CoTCPP SURMOF nanofilms for ultrafast all-optical computing and information processing.

Spherical and lamellar ${\mathrm{\text{Cu}}}_{1.8}\mathrm{\text{S}}$ nanocrystals with radial dimension of about 40nm were synthesized by the thermal injection method. Combining the crystal and morphological analysis with the photo physical property, the lamellar ${\mathrm{\text{Cu}}}_{1.8}\mathrm{\text{S}}$ nanocrystals displayed the typical features of 2D metal sulfides which can be ultrasonically exfoliated into single or few layers of ${\mathrm{\text{Cu}}}_{1.8}\mathrm{\text{S}}$ nanosheets due to the fact that the atomic layers were bonded by interlayer van der Waals forces. While in the spherical ${\mathrm{\text{Cu}}}_{1.8}\mathrm{\text{S}}$ nanocrystals, no exfoliation or morphological change occurred after sonication. The nonlinear optical properties of spherical and lamellar ${\mathrm{\text{Cu}}}_{1.8}\mathrm{\text{S}}$ nanocrystals after sonication were investigated by the $Z$-scanning technique using a 532-nm nanosecond laser pulse. The lamellar ${\mathrm{\text{Cu}}}_{1.8}\mathrm{\text{S}}$ nanocrystals showed saturation absorption, reaching a normalized transmittance of 1.58 at $60\mu \mathrm{\text{J}}$ with a $I_s$ value of $1.65{\mathrm{\text{GW/cm}}}^2$ and $\beta$ value of $-16\mathrm{\text{cm}}{\mathrm{\text{GW}}}^{-1}$. While the spherical ${\mathrm{\text{Cu}}}_{1.8}\mathrm{\text{S}}$ nanocrystals exhibited optical limiting effects, reaching the normalized transmittance of 0.38, with a $\beta$ value of 8cm/GW. Distinct nonlinear absorption behaviors in ${\mathrm{\text{Cu}}}_{1.8}\mathrm{\text{S}}$ nanocrystals with the similar lateral size were observed in the spherical and lamellar ${\mathrm{\text{Cu}}}_{1.8}\mathrm{\text{S}}$ nanocrystals, showing significant geometry feature-dependent nonlinear absorption behaviors.

The nickel molybdate carbon nanotube composites $({\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}})$ were synthesized by solution blending method. The ${\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}}$ were characterized by scanning electron microscopy (SEM), Raman spectroscopy and UV–Vis absorption spectroscopy. The $({\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}})/\mathrm{\text{PMMA}}$ organic glasses were obtained by dispersing ${\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}}$ in methyl methacrylate (MMA) and polymerizing in a water bath at 75°C for 1h. The nonlinear optical (NLO) properties were measured via $Z$-scan technique. By testing we obtained that $({\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}})/\mathrm{\text{PMMA}}$ has a reverse saturation absorption (RSA) effect and optical limiting (OL) performance. In addition, the RSA effect is enhanced compared to other similar materials. The OL threshold ${(F}_{\mathrm{\text{th}}})$ and the normalized transmittance clamping value $(T_c)$ are calculated and fitted to be ${0.83\mathrm{\text{J}}\mathrm{\text{cm}}}^{-2}$ and ${0.48\mathrm{\text{J}}\mathrm{\text{cm}}}^{-2}$, respectively. Consequently, ${\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}}$ have significant research value in the direction of extending new materials for laser protection.

This paper demonstrates the analytical design of an Elliptically polarized Bessel-Gauss beam-based frequency converter by using the guided wave optics concept and Total Internal Reflection Quasi phase matching technique. An anisotropic positive biaxial crystal featuring a rectangular structure of Rubidium Titanyle Phosphate has been used to carry out this analysis. The efficiency of the fourth and fifth harmonic conversion in the projected scheme is 7.05% and 4.3%, respectively, which is approximately three times greater than in a crystal length of approximately 1.4mm and 3.4mm, as provided by the scheme illuminated by a linearly polarized Bessel-Gauss beam at a wavelength of 735nm and 588nm, respectively. The influence of limiting factors, viz Goos Hänchen Shift, surface roughness, absorption, and the diffraction effect rooted in the basic law of nonlinear reflection, has also been taken care of in this analysis. The dependence of conversion efficiency on the length, thickness and angle of incidence of the slab has also been studied.

This paper mainly analyzes the different solutions of the generalized nonlinear Schrödinger equation. First, the coefficients of the equation are divided into variable coefficients and constant coefficients, and their bright and dark soliton solutions are obtained, respectively. Second, the solution was successfully obtained by introducing the series into the equation; Finally, the solution to the Schrödinger equation was obtained through similarity transformation. In addition, by selecting different parameters, some figures of the solutions are displayed.

A hydrothermal synthesis approach was employed to fabricate ZnO and ZnO/Mn nanoparticles. Subsequently, the Stöber method was utilized to prepare ZnO/SiO₂ and ZnO/Mn/SiO₂ nanocomposites using the hydrothermally synthesized ZnO and ZnO/Mn nanoparticles. The successful synthesis of bare ZnO and ZnO-based nanocomposites was confirmed through FTIR spectroscopy and X-ray diffraction analysis. Linear optical characterization led to the calculation of band gap energy amounts utilizing Tauc plot approach. The impact of Mn and SiO₂ additives on the nonlinear optical parameters of the ZnO/Mn/SiO₂ nanocomposites was evaluated through a $Z$-scan setup under pulsed Nd:YAG laser operated at 532nm wavelength. Experimental $Z$-scan effects revealed that both bare ZnO and ZnO-based nanocomposites exhibited negative nonlinearity, for which the values could be controlled by the incorporation of additives to achieve enhanced third-order nonlinear susceptibility values in the order of $10^{-9}$esu. Outcomes demonstrated that while adding of Mn to ZnO host increased the nonlinear optical parameters, the inclusion of SiO₂ led to a slight decrease. However, the simultaneous presence of ZnO, Mn, and SiO₂ resulted in the highest nonlinear optical response. These findings suggest that ZnO/Mn/SiO₂ nanocomposites exhibit a robust nonlinear optical behavior, offering promising prospects as nonlinear media.

This work explains the optical limiting application of manganese-doped copper sulfide nanoparticles. The nanoparticle sizes were definite by powder crystal X-ray diffraction (XRD) analysis metal–sulfide vibration frequencies were identified by FTIR. Morphology, size and shape of material were studied using SEM and TEM analysis. Crystalline order was shown by the EDAX image. The UV–Vis and IR spectrum has been documented in the range between 190 and 1,100nm and it shows that the cutoff wavelength of nanoparticles is around 207nm and found that the energy bandgap value is 175eV and 222eV due to electron–hole threshold energy. Optical third-order nonlinear parameters like nonlinear refractive index $(n_2)$, nonlinear susceptibility $({\chi }^3)$ and nonlinear absorption coefficient $(\beta )$ were calculated by $z$-scan studies.