First theoretical probe for alkynyl bridged thiophene modified coumarin nonlinear optical materials with D-π-A and A-π-D-π-A structures

First-principles exploration is very important to molecular design. In this study, geometric structure, intramolecular charge transfer (ICT), energy levels, polar moment, and ultraviolet–visible (UV–Vis) spectroscopy of eight novel and different alkynyl bridged thiophene modified coumarin nonlinear optical molecules with [Formula: see text]-[Formula: see text]-[Formula: see text] and [Formula: see text]-[Formula: see text]-[Formula: see text]-[Formula: see text]-[Formula: see text] structures had been studied by density-functional theory (DFT) calculations within B3LYP hybrid functional using 6-31 [Formula: see text], [Formula: see text] Gaussian type molecular-orbital basis set. This has guiding significance for the design of nonlinear optical molecules and the development of coumarin-based photoelectric molecules.

Nonlinear optical single crystals for terahertz generation and detection

Nonlinear optical (NLO) single crystals with high quality are the pillars for the development of new devices that fulfil the demands of society. Nowadays, NLO single crystals are very attractive for the photonic applications particularly for terahertz (THz) photonics. The reason for their popularity is that these crystals can produce very powerful and ultra wideband THz waves due to their high nonlinear susceptibility. In this review paper, we deal with the challenges and progresses in the evolution of NLO single crystals for THz wave generation and detection. Here, we review the single crystal growth that how and by which method single crystal is grown. We summarize the structures, intermolecular and intramolecular interactions, their properties and how they generate and detect the THz waves. Widely used single crystals at present are DAST, BNA, OH1, amino acid-based single crystals, etc.

Synthesis, growth and characterization of L-Leucine Magnesium Nitrate Hexahydrate crystal

L-Leucine Magnesium Nitrate HexaHydrate ([Formula: see text]) crystal is a nonlinear optical (NLO) material of semiorganic type. It has grown using a slow evaporation solution growth (SEST) technique at elevated temperature (40∘C) by dissolving LL+MNHH in double distilled water. It was crystalized and recrystalized from a supersaturated solution by stirring it for several hours to get high optical perfection. The X-ray diffraction studies confirmed the presence of the intermixed compound in the [Formula: see text] crystal and possess monoclinic structure. Fourier transform infrared spectroscopy (FTIR) spectrum identified the functional groups of the grown crystal. The crystal has very good optical absorption and transparency in the UV–Vis region. The thermal analysis revealed the thermal stability of the crystal. The dielectric study shows that dielectric constant and dielectric loss decrease at higher frequencies. The crystal showed nonlinear property by second-harmonic generation (SHG) study. This type of material with fair nonlinearity is useful in optoelectronics application devices.

Dynamics of two-dimensional multi-peak solitons based on the fractional Schrödinger equation

We address the propagation dynamics of two-dimensional multi-peak solitons in the optical lattices based on the fractional Schrödinger equation. The effect of Lévy index and lattice depth on the band-gap structure of optical lattices are presented. Two-, three-, four-, six- and eight-peak solitons all can exist in the first gap and be stable in a wide region of their existence domain. The effective width, maximal peak value and the power of soliton are also studied. It indicates that the Lévy index plays a significant role on the properties of solitons.

Numerical study of highly dispersive optical solitons with differential group delay having quadratic-cubic law of refractive index by Laplace–Adomian decomposition

This paper carries out numerical simulations of highly dispersive optical solitons with differential group delay having quadratic-cubic law of nonlinearity. The Laplace–Adomian decomposition scheme is implemented to visualize the soliton propagation dynamics. Both bright and dark solitons are addressed. The error measure for these numerical approximations is impressively low as presented.

Evolution equation for interaction of opposite directed waves with arbitrary polarization in 1D-metamaterial

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.

Bi-directional photonic switch and optical data storage in a hybrid optomechanical system

We propose to achieve quantum optical nonreciprocity in a hybrid qubit-optomechanical solid-state system. A two-level system (qubit) is coupled to a mechanically compliant mirror (via the linear Jaynes–Cummings interaction) placed in the middle of a solid-state optical cavity. We show for the first time that the generated optical bistability exhibits a bi-directional photonic switch, making the device a suitable candidate for a duplex communication system. On further exploring the fluctuation dynamics of the system, we found that the proposed device breaks the symmetry between forward and backward propagating optical modes (optical nonreciprocity), which can be controlled by tuning the various system parameters, including the qubit, which emerges as a new handle. The device thus behaves like an optical isolator and hence can store optical data in the acoustic mode, which can be retrieved later.

Intramolecular charge transfer-based linear and nonlinear optical properties of a D–π–A–π–D type organic chromophore: Experimental and computational approach

In the sight of the present demand of scientific exploration in nonlinear optics (NLO), we synthesized a symmetric donor–[Formula: see text]–acceptor–[Formula: see text]–donor (D–[Formula: see text]–A–[Formula: see text]–D) type organic chromophore [2-[2,6-di((E)-styryl)]-4H-pyran-4-ylidene]malononitrile (M1) for linear and nonlinear optical studies. The structural character of the compound M1 was confirmed using 1H NMR, [Formula: see text]C NMR, and IR spectroscopy. The intramolecular charge transfer (ICT) in molecule M1 has been analyzed using absorption and fluorescence spectrometry in different nonpolar and polar solvents. The optical bandgap, optical conductivity, and linear refractive index of M1 were also calculated using UV–Vis absorption spectrum in CHCl3. The thermogravimetric analysis (TGA) was also carried out to check the thermal stability of the compound M1 and it was found to be thermally stable up to 200∘C. Furthermore, the third-order optical nonlinearity in M1 has been investigated elaborately using the [Formula: see text]-scan technique with a continuous wave (CW) diode laser at 520[Formula: see text]nm. The nonlinear absorption ([Formula: see text]), nonlinear refraction ([Formula: see text]), and nonlinear optical susceptibility ([Formula: see text]) were computed for various solution concentrations as well as several laser powers and the magnitude of all the parameters were found to vary linearly with concentration and power. The magnitude of two-photon absorption cross-section ([Formula: see text]) was also calculated and found to be of the order of 10[Formula: see text] GM. The optical limiting performance of the compound was also studied in different solution concentrations using the same laser. Furthermore, DFT and TD-DFT theoretical calculations were performed for the support of experimental results.

Analysis of highly efficient DFG in an electro-optic material exhibiting polarization rotation using TIR-based ORQPM technique

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 1570[Formula: see text]nm. 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.

Dark soliton solutions of the cubic-quintic complex Ginzburg–Landau equation with high-order terms and potential barriers in normal-dispersion fiber lasers

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.