Journal of Nonlinear Optical Physics & Materials

The topological profiles of the nonlinear optical properties of a two-level molecular system involving simplified versions of intramolecular coupling immersed in a thermal reservoir have been studied in four-wave mixing (FWM) spectroscopy. Solvent effects have been explicitly considered by modeling the nonradiative interaction with the solute as a random variable. To formulate a solution, it is necessary to introduce stochastic considerations. We assume that system–solvent interactions induce random shifts in the Bohr frequency of the adiabatic states, and their manifestation corresponds to the broadening of the upper level. The Born–Oppenheimer (BO) electronic energy curves for this molecular model consist of two intertwined harmonic oscillator potentials shifted in both their position and their minimum equilibrium energy. The critical quantities for this analysis are the transition and permanent dipole moments, which depend strongly on intramolecular coupling. Our results show how absorption and refractive index are affected by vibronic coupling and solvent stochasticity.

In this paper, we discuss a possibility to realize the optical bistability in a rotating semiconductor micro-cavity system. To study the mean cavity photon number profile, we have obtained stationary solution by solving Heisenberg–Langevin equations of motion. In a rotating semiconductor micro-cavity system, bistability is observed when the cavity is driven externally in one direction but not the other direction. The bistable behavior is possible for strong coupling regime, and this can be controlled by hopping strength, decay rates and pump power. The photon profile also shows tunable zero intensity window. The system may be useful to design all-optical switch and optical flip–flop i.e., optical memory element, which would be faster in applications and compact in size.

In this paper, a theoretical study of wave propagation in 1D metamaterial is presented. A system of evolution equations for electromagnetic waves with both polarizations account is derived by means of projection operators method for general nonlinearity and dispersion. It describes interaction of opposite directed waves with a given polarization. The particular case of Kerr nonlinearity and Drude dispersion is considered. In such approximation, it results in the corresponding system of nonlinear equations that generalizes the Schäfer–Wayne one. Traveling wave solution for the system of equation of interaction of orthogonal-polarized waves is also obtained. Dependence of wavelength on amplitude is written and plotted.

This paper is a numeric-analytical work for highly efficient difference-frequency generation (DFG) by the integrated effect of total-internal-reflection-based optical rotation quasi-phase-matching (ORQPM) and nonresonant quasi-phase-matching techniques in a thin yttrium oxide-coated rectangular slab of magnesium oxide-doped lithium niobate crystal. The conversion efficiency of 37.2% has been obtained by ray-optics analysis, corresponding to an idler wavelength of 1570nm. Moreover, the guided-wave approach has also been analyzed for more accurate and realistic outcomes, yielding a peak conversion efficiency of 1.64%. The impact of the influencing factors like surface roughness, absorption, and nonlinear law of reflection has also been incorporated in the computer-aided simulation for providing a pragmatic understanding of the whole study.

In this work, the Au@Ag bimetallic core–shell nanostructures were synthesized by a seed-mediated growth. The crystal structure, morphology, elemental composition, atomic concentration, and absorption spectrum of the as-synthesized nanoparticles were characterized by means of X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and ultraviolet–visible linear absorption spectrum, respectively. The femtosecond third-order optical nonlinearities of nanoparticle dispersions were investigated by carrying out the femtosecond-pulsed $Z$-scan measurements at 800nm. The experimental results indicate that Au@Ag core–shell nanoparticles exhibit the positive refractive nonlinearity and negative absorptive nonlinearity. The third-order nonlinear refraction indexes of Au and Au@Ag nanoparticles are measured to be $2.50\times 10^{-7}$ and $6.39\times 10^{-7}$cm²/GW, respectively. The results show that the bimetallic nanoparticle has potential possibility in nonlinear photonic applications.

In this paper, we numerically study dark solitons in normal-dispersion optical fibers described by the cubic-quintic complex Ginzburg–Landau equation. The effects of the third-order dispersion, self-steepening, stimulated Raman dispersion, and external potentials are also considered. The existence, chaotic content and interactions of these objects are analyzed, as well as the tunneling through a potential barrier and the formation of dark breathers aside from dark solitons in two dimensions and their mutual interactions as well as with periodic potentials. Furthermore, the homogeneous solutions of the model and the conditions for their stability are also analytically obtained.