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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]

Miller's rule is an empirical relation between the nonlinear and linear optical coefficients that applies to a large class of materials but has only been rigorously derived for the classical Lorentz model with a weak anharmonic perturbation. In this work, we extend the proof and present a detailed derivation of Miller's rule for an equivalent quantum-mechanical anharmonic oscillator. For this purpose, the classical concept of velocity-dependent damping inherent to the Lorentz model is replaced by an adiabatic switch-on of the external electric field, which allows a unified treatment of the classical and quantum-mechanical systems using identical potentials and fields. Although the dynamics of the resulting charge oscillations, and hence the induced polarizations, deviate due to the finite zero-point motion in the quantum-mechanical framework, we find that Miller's rule is nevertheless identical in both cases up to terms of first order in the anharmonicity. With a view to practical applications, especially in the context of ab initio calculations for the optical response where adiabatically switched-on fields are widely assumed, we demonstrate that a correct treatment of finite broadening parameters is essential to avoid spurious errors that may falsely suggest a violation of Miller's rule, and we illustrate this point by means of a numerical example. [ABSTRACT FROM AUTHOR]

Organic imidazolium hydrogen fumarate (IHF) crystals are grown using the slow evaporation method. The IHF has triclinic crystal structure. The 1H NMR spectrum has five chemical shifts for the IHF crystal. The band at 3155 cm−1 in IR occurs due to the presence of O─H stretching vibration of the IHF molecule. The bandgap value of the IHF crystal is determined to be 4.6 eV. The intense violet emission band is noted at 361 nm. The IHF crystal has thermal stability value of 179 °C. Hirshfeld surface is used to find out the different intermolecular interactions of the IHF crystal. The HOMO–LUMO energy gap is determined to be 4.70 eV. The hydrogen atoms have positive potential in the MEP analysis. The high stabilization energy of 56.81 kcal mol−1 is noticed for π*(C1─N7) → π*(C2─C3) interaction. The third‐order NLO susceptibility (χ(3)) of the IHF is 2.08934 × 10−9 esu. [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]

Measuring the nonlinear responses of living cells has enabled an understanding of their behavior and functionality. Currently, this response has been studied at radio and optical frequencies, leaving an unexplored gap in the field of microwaves. This paper presents a system that combines microwave technology with a microfluidic platform to measure the nonlinear susceptibility of living organisms to electromagnetic fields. The applied technique involves feeding the system with two tones (2.1 GHz and 4 GHz) to generate third-order intermodulation products (PIMP) at 5.9 GHz. Nonlinear susceptibility was measured from the power levels of PIMP using a spectrum analyzer. Broadband electrodes based on the slot bowtie geometry were manufactured to operate at 5 GHz with a bandwidth of 4 GHz. Additionally, an engineering process is presented to optimize the power of the internal mixer of the spectrum analyzer to obtain the maximum dynamic range and improve the sensitivity of the system. Nonlinear susceptibility to microwaves was analyzed in four samples: pure ethanol, a mixture of ethanol and dimethyl sulfoxide (DMSO), live Escherichia coli (E. coli), and heat-killed E. coli. The results show that ethanol has zero nonlinear susceptibility, whereas when it is mixed with DMSO, a nonlinear response appears at a value of 4 dB with respect to the nonlinear susceptibility of the system in the absence of a sample. Finally, the nonlinear susceptibility of live E. coli to microwaves was detected, with a difference of 8 dB over the reference value and 6 dB with respect to the heat-killed E. coli sample.

We extend the nonstandard (NS) finite difference time domain (FDTD) methodology, originally developed to solve Maxwell's equations in linear materials, to nonlinear ones. We validate it by computing harmonics generation in a nonlinear dielectric and comparing with theory. The methodology also applies to the quantum electrodynamics that describes the interaction of charged particles with electromagnetic fields, and also to the Ginzburg-Landau model of superconductivity. [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]

In this work, we report the experimental study of a Q-switched optical fiber laser based on graphene oxide quantum dots (GOQDs) as saturable absorber (SA). GOQDs are fabricated by carbonization and exfoliation electrospun polyacrylonitrile (PAN) fibers. The results of Fourier Transform Infrared Spectroscopy (FTIR) showed bands caused by the CHs and CO groups associated with the GOQDs. The Raman spectrum showed the typical G and D bands of GOQDs. The size of the GOQDs, calculated by Transmission Electron Microscopy (TEM) was 6 nm; additionally, by high resolution TEM (HRTEM), an interplanar distance of 0.19 nm corresponding to the (002) direction of the graphene oxide was calculated. The SA was achieved using the photodeposition technique of the GOQDs onto the core of a single-mode optical fiber. The nonlinear characterization (NLC) of the GOQDs was carried out using the P-scan technique with a high-gain erbium-doped fiber amplifier (EDFA) at a wavelength of 1550 nm. The obtained results showed a saturable absorption behavior with a value of β=−1.178x10−6(m/W) and a non-linear susceptibility of Im(χ(3))≈−1.573x10−7(esu). The experimental results of the SA, based on GOQDs as a switching device in a fiber laser, showed a typical behavior of a Q-switched laser by generating a pulsed emission at a wavelength of 1599 nm, a frequency from 2 to 16 kHz, and a maximum average output power of 1.3 mW.

We present a study of high efficient terahertz (THz) wave generation in DASB/GaAs, DASC/GaAs, and DAST/GaAs multilayer structures at 1.5THz via difference frequency generation (DFG) process with 1.5µm femtosecond laser pulses. We also compare the conversion efficiency in proposed structures with DASB/SiO2, DASC/SiO2, and DAST/SiO2 multilayer structures and bulk crystals DASB, DASC, and DAST. These structures compensate for phase mismatching in bulk crystals DASB, DASC, and DAST and increase conversion efficiency from 10-5 in bulk organic crystals up to 10-3 in multilayer structures. We show that DASC/GaAs is the best structure to generate 1.5THz waves.

The linear dynamic susceptibility is arguably the most important property to specify the magnetization dynamics of a given system. Therefore, this quantity has been studied in great detail and the corresponding measurements known as susceptometry are well-established. Notwithstanding its relevance, the linear susceptibility is inherently limited to describe the magnetization response to weak external fields only. Here, we suggest the framework of Medium Amplitude Field Susceptometry (MAFS) to study the non-linear response which complements the linear susceptibility and provides additional information on the magnetic properties of the system and is applicable to magnetic fields of medium amplitudes. In particular, we introduce the general third-order nonlinear susceptibility χ ˆ 3 as a central quantity that completely specifies the lowest-order non-linear response to arbitrary time-dependent magnetic fields. We show that response functions in medium amplitude oscillatory magnetic fields and parallel superposition susceptometry are contained in χ ˆ 3 as special cases. Also included in χ ˆ 3 are interesting intermodulation effects when the system is probed by a superposition of oscillating magnetic fields with different frequencies. We work out the explicit form of χ ˆ 3 for several model systems for the dynamics of magnetic nanoparticles (MNPs). We expect this unifying framework to be not only of theoretical interest, but also useful for a deeper characterization of MNP systems, giving additional information on their suitability for various applications. [Display omitted] • Extend traditional alternating current (AC) susceptometry from the linear regime to magnetic fields of moderate amplitude. • Introduce third-order nonlinear susceptibility χ ˆ 3 (ω 1 , ω 2 , ω 3) as central new quantity. • Weakly nonlinear regime fully specified by χ ˆ 3 for arbitrary time-dependent fields. • Mean amplitude and parallel superposition susceptometry are special cases of χ ˆ 3. • Intermodulation effects provide additional insights. • Explicit form of χ ˆ 3 (ω 1 , ω 2 , ω 3) worked out for particular model systems of magnetic nanoparticles. [ABSTRACT FROM AUTHOR]

As a representative transition metal oxide, cupric oxide (CuO) has attracted a lot of interest in miscellaneous fields. In the present work, the prominent third-order nonlinear optical (NLO) features of CuO nanosheets were demonstrated via the typical Z-scan technique at 1 μm. The open-aperture (OA) Z-scan measurements at different intensities clearly showed that CuO nanosheets possessed the saturable absorption (SA), reverse saturable absorption (RSA) and optical limiting behaviors. The closed-aperture (CA) Z-scan technology was implanted to investigate the nonlinear refractive index and the third-order nonlinear susceptibility. In virtue of the strong nonlinear optical absorption properties of CuO nanosheets, a stable all-solid-state mode-locked laser with the as-prepared CuO nanosheets as saturable absorber at 1.06 μm was realized for the first time. Our work confirmed that CuO nanosheets exhibited outstanding NLO properties, which might stimulate the development in ultrafast photonics and nonlinear optics.

The nonlinear optical response of graphene oxide quantum dots (GOQDs) fabricated by the carbonization and exfoliation of electrospun polyacrylonitrile (PAN) fibers is reported. Electrospun and carbonized fibers were characterized by SEM and XPS. SEM micrograph confirmed the formation of PAN fibers of 153.44 ± 6.44 nm, while by XPS the binding energies associated with sp2 and sp3 carbon hybridizations were found, after the carbonization process. On the other hand, the GOQDs obtained were characterized by photoluminescence (PL), UV–Vis, Raman spectroscopy, and High-Resolution Transmission Electron Microscopy (HRTEM). The GOQDs size of 10 nm was estimated by HRTEM. Raman spectroscopy showed the D and G bands associated with the sp2 and sp3 hybridizations of the GOQDs, by PL two energy values of 2.67 and 2.97 eV were calculated. The UV–Vis spectrum showed two absorption bands confirming the presence of GOQDs. The nonlinear characterization was carried out using the P-scan technique, previously photodepositing GOQDs onto an optical fiber, using a coherent radiation source at a wavelength of 1550 nm. The results obtained showed a saturable absorption behavior with a value of β=−2.474×10−4m/W and a nonlinear susceptibility of χ(3)≈−7.749×10−4(esu). The results of this work showed that GOQDs obtained can be used for optical switching applications.

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]

Abstract Nonlinear-optical response of photorefractive hybrid liquid crystal (LC) cells has been studied by means of dynamic holographic technique in two-wave mixing arrangement. The LC cells include nonuniform silicon substrates comprising a micrometer-range photonic crystal. A thin LC layer is set between silicon substrate and a flat glass substrate covered by a transparent (ITO) electrode. A dynamic diffraction grating was induced in the LC volume by the two-wave mixing of laser beams with simultaneous application of DC electric field to the cell. Theoretical model of Raman-Nath self-diffraction was developed. This model allows for calculation of nonlinear optical characteristics in thin samples on the base of two-wave mixing experimental data, and with taking into account light losses on absorption and/or scattering. The hybrid LC cells demonstrate strong nonlinear optical effect, prospective for many applications in electro-optical microsystems, such as SLMs, as well as in multi-channel systems.

The manuscript reports the effect of Bi content on the linear and nonlinear optical properties as well as the structural and physical properties in thermally evaporated As 40 Se 60-x Bi x chalcogenide thin films. The optical properties of the as-deposited films have been studied from the optical transmission data recorded by UV–Visible spectrometer. The linear optical parameters (linear refractive index n, extinction coefficient k, absorption coefficient α), indirect optical band gap, Urbach energy, oscillator energy, dispersion energy were calculated from the transmission data which were strongly influenced by Bi content. The dispersion of refractive index was analyzed in terms of single oscillator Wemple-Di Domenico model. The third order nonlinear susceptibility (χ(3)) and nonlinear refractive index (n 2) were calculated from the linear parameters using semi-empirical relations. The optical gap decreased which was discussed by chemical bond approach and degree of disorder possessed by the films. The optical properties changes in the films were also well supported by the Raman shift. The structural characterization by X-ray diffraction revealed the amorphous nature of the prepared films whereas the composition and micro structure of the studied films were probed by energy dispersive X-ray analysis and field emission scanning electron microscopy study. Image 1 • The value of χ(3), n 2 , σ opt , absorption coefficients increased with Bi content. • The increase in refractive index is due to the increase in polarizability and . • The reduction in E g is due to the increase in density of localized states. • The E o and B1/2 decreased while E d , E e , ε L , N/m*,n 0 , n increased with Bi content. • The linear and nonlinear optical response are suitable for nonlinear optical devices. [ABSTRACT FROM AUTHOR]

Highlights • SPIONs are selectively detected in the diamagnetic human body. • Unique about our laparoscopic probe is separation of excitation and detection coils. • Active compensation enables independent movement of detection coils. • This is possible because we use Differential Magnetometry (DiffMag). Abstract A novel probe for laparoscopic in vivo detection of superparamagnetic iron oxide nanoparticles (SPIONs) has been developed. The main application for in vivo detection of SPIONs our research group aims at is sentinel node biopsy. This is a method to determine if a tumor has spread through the body, which helps to improve cancer patient care. The method we use to selectively detect SPIONs is Differential Magnetometry (DiffMag). DiffMag makes use of small magnetic field strengths in the mT range. For DiffMag, a handheld probe is used that contains excitation and detection coils. However, depth sensitivity of a handheld probe is restricted by the diameter of the coils. Therefore, excitation and detection coils are separated in our novel probe. As a result, excitation coils can be made large and placed underneath a patient to generate a sufficiently large volume for the excitation field. Detection coils are made small enough to be used in laparoscopic surgery. The main challenge of this setup is movement of detection coils with respect to excitation coils. Consequently, the detector signal is obscured by the excitation field, making it impossible to measure the tiny magnetic signature from SPIONs. To measure SPIONs, active compensation is used, which is a way to cancel the excitation field seen by the detection coils. SPIONs were measured in various amounts and at various distances from the excitation coils. Furthermore, SPIONs were measured in proximity to a surgical steel retractor, and 3 L water. It is shown that small amounts of SPIONs (down to 25 μg Fe) can be measured, and SPIONs can be measured up to 20 cm from the top of the excitation coil. Also, surgical steel, and diamagnetism of water – and thus of tissue – have minor influence on DiffMag measurements. In conclusion, these results make this novel probe geometry combined with DiffMag promising for laparoscopic sentinel node biopsy. [ABSTRACT FROM AUTHOR]

The study is based on annealing-induced Bi diffusion into Se 30 S 30 Sb 40 sites that bring modification in its linear-nonlinear optical, structural, and dielectric properties. The Bi/Se 30 S 30 Sb 40 heterostructure film was annealed at 100,150,200 and 250 °C. The Bi 2 Se 3 and Sb 2 Se 3 phase formation was confirmed from the X-ray diffraction as well as from the Raman study. The morphology has been studied by the field emission scanning electron microscopy images with increased particle size upon annealing. The uniformity and homogeneity of the film were noticed from the energy dispersive X-ray analysis elemental mapping. The bandgap decreased from 1.461 eV (as-prepared Bi/Se 30 S 30 Sb 40) to 1.258 eV (250 °C annealed) with an increment in static refractive index from 2.864 to 3.114 which was noticed from the optical study. The linear optical parameters were tuned with annealing conditions and such changes were understood from the concept of density of states and defects in the film. The increase in dielectric loss factor and decrease in quality factor with annealing is accompanied by the increase in both electronic and optical conductivity. The plasma frequency decreased and optical electronegativity reduced from 1.728 (as-prepared Bi/Se 30 S 30 Sb 40) to 1.692 (250 °C annealed) with annealing. The value of 3rd-order nonlinear susceptibility and non-linear refractive index gets almost doubled (i.e. 1.838 × 10−11 to 3.913 × 10−11 esu and 2.419 × 10−10 to 4.735 × 10−10 esu respectively) with annealing with an increase in the nonlinear absorption coefficient. The hydrophilic nature of the films with annealing was observed from the surface wettability study. The computational study by density functional theory provided the necessary idea for structural and physical parameters of the films. [Display omitted] • Increase in nonlinear refractive index and 3rd order nonlinear susceptibility upon annealing Bi/Se 30 S 30 Sb 40 films. • Optical electronegativity decreased and the nonlinear absorption coefficient increased. • Films became more hydrophilic in nature after annealing. • Decrease in the optical bandgap is due to a change in the local structure. • Increase in dielectric constants is suitable for dielectric applications [ABSTRACT FROM AUTHOR]

The present study extensively investigates the optical and structural properties of β-H 2 Pc thin films before and after annealing at temperatures of 373, 423, 473, 523, and 573 K/1 h, enabling the design of efficient organic-based devices. The mean crystallite size was calculated from XRD and found to be 8.5 nm at 300 K, which increased as the annealing temperature increased, confirming the crystallinity improvement upon annealing. In addition, the SEM images revealed that the grain size increased with increasing annealing temperature. The FTIR results confirmed the high thermal and chemical stability upon annealing. Furthermore, increasing the annealing temperature leads to a decrease in the transmittance spectrum and an increase in the reflectance spectrum. The results revealed a decrease in the optical band gap of β-H 2 Pc films from 1.472 eV to 1.406 eV for the onset gap and from 2.44 to about 2.21 eV for the fundamental gap with increasing annealing temperature to approximately 573 K. Moreover, the nonlinear optical parameters show an increase with higher thermal treatment temperatures. The annealing process has a significant impact on the optical and structural properties, leading to noticeable variations at specific annealing temperatures. [Display omitted] [ABSTRACT FROM AUTHOR]

This theoretical study investigates the response of a strongly oblate GaAs ellipsoidal quantum dot to an intense laser field with a Bessel intensity profile at non-resonant extreme violet and simultaneously resonant mid-infrared laser irradiation. Mainly, the linear and nonlinear optical properties of biexcitons in quantum dot are observed. Due to the complexity of the considered particle, all calculations are performed in the framework of the variational method. Biexciton variational function is constructed on the one-particle wave functions, which are correlated with each other by exponents with variational parameters. The biexciton energies for different values of applied intense laser field magnitude on the small geometrical parameter of ellipsoidal quantum dot are calculated. The nonlinear optical properties, including the oscillator strength, third-order nonlinear susceptibility, absorption coefficient, and refractive index change, are evaluated. Numerical results reveal the dependence of the exciton and biexciton energies on the intensity of the laser field and the geometrical parameters of the quantum dot. Additionally, the dependencies of the third-order susceptibility, absorption coefficient, and induced refractive index change on photon energy near the one-photon resonance and two-photon resonance are analyzed. The two-photon absorption coefficient of the biexciton in GaAs ellipsoidal quantum dot is computed, and the spectra of refractive index changes induced by biexciton transitions between ground states are analyzed for different magnitudes of the intense laser field. Biexciton recombination radiative lifetime on the small semiaxis of the ellipsoidal quantum dot for the different values of the laser field influence is estimated. Finally, the visualization of the localization region of biexciton in the ellipsoidal quantum dot is performed. • Investigation of biexciton states in quantum dot under intense Bessel laser. • Calculations of biexciton energies using the variational method. • Investigation of one-photon and two-photon resonances transitions. • Estimation of recombination lifetimes and visualization of localization. [ABSTRACT FROM AUTHOR]

The crucial role of nonlinear propagation effects in the self-guiding of femtosecond laser pulses required accurate representation of nonlinearities to describe them. In this paper, an improved theoretical model has been proposed to study the height distribution of the atmospheric nonlinear refractive index. The results show that the revised model obviously improves accurate estimation of nonlinear index at the long wavelength band. Based on the model, we also found the atmospheric nonlinear refractive index differs much from the lower atmosphere to the upper atmosphere. Our results are essential for engineering applications based on the long-distance ultrashort laser pulses' transmission in diverse atmosphere. [ABSTRACT FROM AUTHOR]

Abstract Both coherent Third Harmonic Generation (THG) at the interfaces of a cuvette filled with a nanocrystal suspension and incoherent Second and Third Harmonic Scattering (THS) from the suspension volume have been studied to quantitatively assess the orientation-averaged third-order susceptibility 〈 χ N P s (3) 〉 of ZnO. These two complementary experimental approaches are based on different calibration routes with a nanocomposite model and fused-silica as a reference material for THG, and pNa molecules for THS. Similar and consistent absolute values of 〈 χ N P s (3) 〉 (above 10 − 18 m2/V2) are derived and discussed according to the particular orientation averaging procedure that holds for each experimental configuration for a 1064 nm excitation wavelength. Highlights • Coherent THG and incoherent THS from ZnO nanocrystal suspensions. • Averaged third-order susceptibility derived at 1064 nm for each experimental configuration. • Orientation averaging procedure, experimental benefits/caveats and calibration routes detailed. [ABSTRACT FROM AUTHOR]

The influence of 532 nm laser irradiation on the optical changes of Ag 2 S/As 2 Se 3 thin films. The irradiation influenced the linear and the nonlinear optical parameters. [Display omitted] • 532 nm laser irradiation on Ag 2 S/As 2 Se 3 thin films has been investigated. • The optical stability of the film under prolonged irradiation is observed from the small change (<10%). • The nonlinearity (χ(3) and n 2) increased with irradiation time. • The optical conductivity and dielectric parameters increased with irradiation time. • Electrical susceptibility decreased with the decrease in nonlinear absorption coefficient (β c). The time dependent laser induced effects on the linear and nonlinear optical properties of Ag 2 S/As 2 Se 3 heterostructure films has been investigated in the current study. The Ag-S-Se-As solid solution formed from the intermixing of Ag 2 S and As 2 Se 3 layers brings changes in the absorption edge and other optical parameters. The increase in transmittance gradually saturated followed by small increase in absorbance. The reduction in bandgap from 1.572 eV to 1.52 eV is due to the increase in defect states and disorder in the film because of the intermixing of two layers. The static refractive index is increased by 6.03% which enhanced the nonlinear refractive index by 38% upon laser irradiation. The optical conductivity increased while the electrical susceptibility decreased with the increase in laser irradiation time duration. The dielectric loss factor increased that reduced the quality factor. The increase in carrier concentration reduced the optical electronegativity upon laser irradiation. The third order nonlinear susceptibility (χ(3)) is doubled at 120 min. laser irradiation. The amorphous nature remains unchanged with laser irradiation as probed by XRD and Raman study. The surface roughness is not much changed as found from AFM study. The stability in structure and morphology of the films make them appropriate candidate for optoelectronic applications, in particular those exposed frequently to laser source. [ABSTRACT FROM AUTHOR]