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We construct a new exact solution of the problem of a filament placed parallel to the interface between two insulators, one of which has a nonlinear susceptibility. [ABSTRACT FROM AUTHOR]

The electronic properties of ZnIn2Se4 crystals have been studied experimentally by spectral ellipsometry and theoretically (from the first principles) using the density functional theory (DFT). Ellipsometric studies in the energy range of 0.7–6.5 eV made it possible to determine the imaginary and real parts of the dielectric function and optical conductivity, as well as the dispersion of the refractive indices, extinction coefficients, and absorption coefficients, and to estimate the values of the Urbach energy, plasma frequency, and nonlinear optical characteristics of ZnIn2Se4 crystals. The electronic band structure, origin of energy states, optical functions for incident light polarized along the crystal optic axis and perpendicular to it, and partial densities of states projected onto atoms are determined by ab initio calculations. The theoretical results are compared with the experimental data obtained by spectral ellipsometry. [ABSTRACT FROM AUTHOR]

In this study, the effects of gamma radiation with doses ranging from 0 KGy to 100 KGy on the structural and optical properties of the Beta Metal-free Phthalocyanine (β-H2Pc) powder and films were investigated. X-ray diffraction and scanning electron microscope were used to examine the crystalline and morphological structures of the thin films. While Fourier transform infrared and absorption spectra were utilized to study the changes in molecular structure and energy absorption, respectively. The results showed that while γ-irradiation induced changes in the surface morphology and optical properties of β-H2Pc, the molecular structure remained stable except for the disappearance of the hydroxyl (OH) functional group peak. The irradiation dose was found to affect the dielectric constants, dispersion characteristics, and nonlinear optical susceptibility of the material. The β-H2Pc thin films exhibited high absorption coefficients and refractive index values, making them promising candidates for optoelectronic devices such as solar cells. However, careful consideration of the effects of gamma irradiation on other properties of β-H2Pc such as stability, toxicity, and cost-effectiveness is necessary. [ABSTRACT FROM AUTHOR]

The present article demonstrates the photophysical and nonlinear optical studies of the chromophore 2,2'-(hexane-1,6-diylbis(9 H-carbazole-9,3-diyl))bis(ethene-1,1,2-tricarbonitrile (HCzN). The structure and the purity of the synthesized molecule have been confirmed via Infrared (IR) and Nuclear Magnetic Resonance (NMR) spectroscopies. Absorption and emission spectroscopies have been performed to understand the photophysical properties and we have enumerated the absorption coefficient (α0), refractive index (n0), optical bandgap (Eg), and optical conductivity (σ) for this chromophore. We have also explored the third-order nonlinear optical (NLO) characteristics of HCzN at the concentrations of 1, 2, 3, and 4 mM employing both closed and open-aperture Z-scan methods at 25 mW laser power. This chromophore evinces the self-defocusing and saturable absorption nature for closed and open aperture scans respectively. The calculated NLO parameters such as the coefficients of nonlinear refraction (n2) and nonlinear absorption (β) are found to be of the order of 10−6 cm2/W and 10−3 cm/W respectively with the nonlinear optical susceptibility (χ(3)), and hyperpolarizability (γ) of the order of 10−5 esu and 10–27 esu respectively. The magnitude of NLO parameters varies linearly concerning the concentration. The enhanced values of NLO parameters of chromophore HCzN shows its potential in photonic applications. [ABSTRACT FROM AUTHOR]

Abstract: Binary glasses of Ge25Se75 are prepared by melt quench technique. Two layers of thin film have been done by the conventional thermal evaporation technique on glass substrate. Ge25Se75 with 340 ± 5 nm thickness is prepared as first layer, then thin silver layer is evaporated on top of the Ge25Se75 film. The Ge25Se75 with Ag on top of the film were annealed at different time of 30, 60, 90, and 180 and 210 min at temperature of 573 K. Subsequently, we have analyzed these films using scanning electron microscopy (SEM) and X-ray diffraction (XRD) to confirm the successful diffusion of Ag on Ge25Se75 films. XRD measurements show that as prepared Ag/Ge25Se75 have amorphous natures. Optical transmission and reflection spectra of the studied thin films are measured in the wavelength range of 200–2500 nm at room temperature. The optical properties of the new films were studied before and after annealing at different annealing times due to gradually thermal diffusing of Silver on Ge25Se75. The absorption coefficient (α) as an optical constant is determined as a function of annealing times. Moreover, the values of the third-order nonlinear optical susceptibility increased with an increase of annealing temperatures due to gradually thermal diffusing of Silver. The gradual thermal diffussion of Ag on amorphous GeSe thin film causes a change in the nonlinear refractive index and third order type nonlinear optical susceptibility. The results indicate that Ag/Ge25Se75 has great potential for various applications including optical sensors and optoelectronics. [ABSTRACT FROM AUTHOR]

Generalized Kramers–Kronig (K–K) type dispersion relations and sum rules are derived in the static limit for the moments of the degenerate four wave mixing susceptibility. The degenerate nonlinear susceptibility is different from a typical use of the conventional K–K dispersion relations, which assume absence of complex poles of a function in the upper half of complex frequency plane, whereas degenerate susceptibility has simultaneous poles in both half planes. In the derivation of the generalized K–K relations the poles and their order are taken into account by utilization of the theorem of residues. The conventional K–K relations can be used to estimate the real and imaginary parts of the second and higher powers of the susceptibility as the effect of the poles is reduced due to a faster convergence of the dispersion relations. The present theory is directly applicable to higher order susceptibilities and can be used in testing of theoretical models describing the degenerate four wave mixing susceptibility in nonlinear optical and terahertz spectroscopy. [ABSTRACT FROM AUTHOR]

The rare earth Pr3+ and Yb3+ doped phosphate glass were prepared by quenching method using electrical muful furnace. The optical band gap of rare earth Pr3+ and Yb3+ doped phosphate glass were studied. The dielectric permittivity, dielectric loss and electrical conductivity of the prepared samples have been studied using LCR meter with different frequencies at room temperature. The Vickers hardness number, brittle index, yield strength, fracture toughness of the rare earth Pr3+ and Yb3+ doped phosphate glasses were also calculated. The nonlinear optical parameters such as third order nonlinear coefficient and nonlinear refractive index were estimated using Z-scan method. The magnetic property of the Pr3+ and Yb3+ doped phosphate glass was studied using VSM analysis. The electro chemical properties of Pr3+ and Yb3+ doped phosphate glass electrodes in 5 M KOH electrolyte were studied using cyclic voltammetry, Galvanostatic charge–discharge and electrochemical impedance spectroscopy. The specific capacitance, energy density and capacity retention of Pr3+ and Yb3+ doped phosphate glasses were calculated. [ABSTRACT FROM AUTHOR]

The renormalized coupling constants g that enter the equation of state and determine nonlinear susceptibilities of the system have universal values g at the Curie point. We use the pseudo- ε-expansion approach to calculate them together with the ratios R = g / g for the three-dimensional scalar λ ϕ field theory. We derive pseudo- ε-expansions for g , g , R , and R in the five-loop approximation and present numerical estimates for R and R . The higher-order coefficients of the pseudo- ε-expansions for g and R are so small that simple Padé approximants turn out to suffice for very good numerical results. Using them gives R = 1.650, while the recent lattice calculation gave R = 1.649(2). The pseudo- ε-expansions of g and R are less favorable from the numerical standpoint. Nevertheless, Padé-Borel summation of the series for R gives the estimate R = 0.890, differing only slightly from the values R = 0.871 and R = 0.857 extracted from the results of lattice and field theory calculations. [ABSTRACT FROM AUTHOR]

We explicitly present an experimentally feasible scheme for generating spin squeezed state of photons via a degenerate parametric down-converter. The evolution of the mean spin vector can be regarded as a precession under some conditions. The spin squeezed state can be generated rapidly in the dynamical process by adjusting some correlative parameters. The strongest squeezing is independent of the detuning, but a larger one induces over a relatively longer squeezing time interval. [ABSTRACT FROM AUTHOR]

Regarding the importance of type I collagen in understanding the mechanical properties of a range of tissues, there is still a gap in our knowledge of how proteins perform such work. There is consensus in literature that the mechanical characteristics of a tissue are primarily determined by the organization of its molecules. The purpose of this study was to characterize the organization of non-irradiated and irradiated type I collagen. Irradiation was performed with a linearly polarized HeNe laser ( λ = 632.8 nm) and characterization was undertaken using polarized light microscopy to investigate the birefringence and second harmonic generation to analyze nonlinear susceptibility. Rats received laser irradiation ( P = 6.0 mW, I = 21.2 mW/cm, E ≈ 0.3 J, ED = 1.0 J/cm) on their healthy Achilles tendons, which after were extracted to prepare the specimens. Our results show that irradiated samples present higher birefringence and greater non-linear susceptibility than non-irradiated samples. Under studied conditions, we propose that a red laser with polarization direction aligned in parallel to the tendon long axis promotes further alignment on the ordered healthy collagen fibrils towards the electric field incident. Thus, prospects for biomedical applications for laser polarized radiation on type I collagen are encouraging since it supports greater tissue organization. [ABSTRACT FROM AUTHOR]

In the present frame of work, optical bistability using a Fabry-Perot cavity containing bis (4-dimethylaminodithiobenzyl)-nickel (BDN) dye entrapped in PMMA matrix is experimentally investigated by using a single-mode Q-switched nanosecond Nd: YAG laser operating at 532 nm. The optical nonlinear parameters such as nonlinear refractive index ( n) and cubic susceptibility ( χ) of the material are numerically estimated from bistability loop. The origin of optical bistable behavior is attributed to nonlinear refraction. The study shows that BDN dye in solid-state matrix is a promising candidate for optical switching element. [ABSTRACT FROM AUTHOR]

review of the detection of pulsed terahertz waves via field-induced second harmonic generation in gaseous media is presented. The effects of the DC bias field strength, probe pulse energy, nonlinear susceptibility of the gases, gas pressure, and focusing conditions of the terahertz and optical beams are discussed. A Figure-of-merit, which characterizes the sensitivity of gases media, is introduced. [ABSTRACT FROM AUTHOR]

We investigate how equilibrium entanglement is manifested in the nonlinear response of an N-qubit system. We show that in the thermodynamic limit the irreducible part of the nth-order nonlinear susceptibility indicates that the eigenstates of the system contain entangled (n + 1)-qubit clusters. This opens the way to a directly observable multiqubit entanglement signature. We show that the irreducible part of the static cubic susceptibility of a system of four flux qubits, as a function of external parameters, behaves as a global 4-qubit entanglement measure introduced in Ref. (20). We discuss the possibility of extracting purely-entanglement-generated contribution from the general multipoint correlators in a multiqubit system. [ABSTRACT FROM AUTHOR]

The influence of “treatment” in a magnetic field at low temperatures on the nonlinear optical properties of NiI2-doped CdI2 single crystals is investigated. The impurity ions in the interlayer space or more complex centers into which these ions enter can align on exposure to a magnetic field due to the interaction with the membrane vibrations of the lattice and create residual polarization in a specimen. This polarization causes redistribution of the electric charge on the bonds and improves the nonlinear optical properties of single crystals. [ABSTRACT FROM AUTHOR]

A dispersion theory for linear optical properties of two-phase layered-geometry nanocomposites is presented. Generalized dispersion relations and sum rules are stated using the results from complex analysis. The concept of Lorentzian linear susceptibility is exploited in theoretical treatment of the effective linear susceptibility of the nanocomposite. The meromorphism of total reflectance in the case of effective meromorphic nonlinear susceptibility was observed. [ABSTRACT FROM AUTHOR]

The magnitude of the χ element of the third-order optical susceptibility was measured in a series of wurtzite phase GaN nucleation layers (∼450Å) deposited on (00.1) sapphire at 540°C and annealed to various temperatures up to 1050°C. The nonlinear optical response exhibited a significant increase in films that were annealed to temperatures in the range of 1015 to 1050°C. In addition, the correlation between the magnitude of χ with both the maximum value of the linear absorbance gradient and the residual homogeneous strain in the overlayer suggests that variations in the crystalline content of the film and the bonding distance between the Ga and N atoms are primary factors in determining the third-order nonlinearity in GaN. [ABSTRACT FROM AUTHOR]