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Multi‐aryl compounds, with conjugated backbones having electron donor and acceptor groups, are widely recognized for their significant nonlinearity. In this context, a new terphenyl compound, ethyl‐4″‐chloro‐5′‐hydroxy‐[1,1′:3′,1″‐terphenyl]‐4′‐carboxylate (EHCMT), has been synthesized for potential use as an optoelectronic material. Single crystal X‐ray diffraction (XRD) analysis of EHCMT revealed a triclinic system with the centrosymmetric space group P1¯${\mathrm{P}}\bar{1}$, providing most accurate description for its crystal structure. The structure of compound was further elucidated through FTIR, NMR (1H, 13C & 2D‐HSQC), and UV–Visible spectroscopic techniques. Hirshfeld surface analysis was employed to examine the magnitude and significance of individual intermolecular interactions in the crystalline arrangement. The third‐order nonlinear optical (NLO) properties were investigated using the Z‐scan technique in a solution phase at 532 nm. The study revealed significant results, namely, nonlinear refraction value of −1.165 × 10−9 cm2 W−1, nonlinear absorption coefficient value of 13.4 × 10−5 cm W−1, and third‐order nonlinear susceptibility value of 0.50 × 10−7 esu. The structural parameters of experimental results were validated by comparing the same with quantum chemical calculations using hybrid functional, namely, Hartree–Fock ‐ Density functional theory (HF–DFT). [ABSTRACT FROM AUTHOR]

This research presents the optical limiting properties of a novel axially linked D‐A type compound, LaPc‐C60(OH)n, where lanthanide phthalocyanine serves as the donor and fullerenol as the acceptor. The incorporation of fullerenol expands the π‐conjugated system, decreases the aggregation of the phthalocyanine, and significantly increases the solubility of the compound. The establishment of this D‐A system promotes intramolecular electron transfer, effectively improving both the non‐linear optical (NLO) response and optical limiting properties. In addition, homogeneous poly(methyl methacrylate) (PMMA) composite films (LaPc‐C60(OH)n/PMMA) are prepared using a simple solution casting method. Compared to fullerenol or lanthanum phthalocyanine individually, LaPc‐C60(OH)n exhibited a superior NLO response both in solution and in the solid composite film. In particular, LaPc‐C60(OH)n/PMMA demonstrated an increase in the non‐linear absorption coefficient (2050 cm GW−1) and a larger third‐order magnetization (1.84 × 10−8 esu). In addition to exhibiting an excellent NLO response at 532 nm, LaPc‐C60(OH)n also shows significant NLO enhancement at 1064 nm, extending the limiting range into the near‐infrared region. This behavior is attributed to different nonlinear absorption mechanisms and the synergistic effect that arise from the photo‐induced electron transfer process between the fullerenol and LaPc. [ABSTRACT FROM AUTHOR]

Creating heterojunctions or composites by incorporating noble metals offers a remarkable means to modulate the electronic charge transfer and the nonlinear optical (NLO) properties in 2D transition metal dichalcogenides (TMDCs). The response of such 2D‐TMDC‐noble metal composites to femtosecond (fs) infrared (IR) and terahertz (THz) radiation, however, remains vastly unexplored. While the linear optical characteristics of a prototypical 2D‐TMDC, namely, MoSe2 nanosheets incorporated with noble metal (such as Au, Pt, and Ag) nanoparticles in the UV–Vis and the THz spectral range, the NLO characteristics are measured using a 70‐fs pulse at 800 nm excitation is investigated. The results demonstrate a clear reduction of band gap with the incorporation of noble metals in MoSe2, indicating an effective charge transfer mechanism at play. Notably, the MoSe2‐noble metal nanocomposites depicted a significant enhancement in the THz conductivities. In addition, a dramatic 4‐fold enhancement in the third‐order nonlinear coefficient and ≈2‐fold enhancement in the third‐order NLO susceptibility is achieved in MoSe2‐Ag nanocomposite. These results univocally suggest that the noble metal‐based composites with suitable charge transfer channels promote enhanced carrier mobilities and tunable electron transfer dynamics, making these hybrid materials promising candidates for optoelectronic applications both at IR and THz frequencies. [ABSTRACT FROM AUTHOR]

Two Curcumin (Cur) based mixed ligand complexes of Nickel have been investigated for their optical nonlinearity (NLO). Physicochemical characterization of two nickel precursors and their interaction with curcumin produced two molecules, namely Ni(C3S5)(Cur).2H2O (abbreviated as NiThCur) and NiCl(Cur)(PPh3) (abbreviated as NiTppCur). Additionally the Conceptual‐Density‐Functional‐Theory (CDFT) studies were performed. CDFT‐based optimization parameters of both molecules are theoretically interpreted. HOMO‐LUMO energy gap of NiThCur and NiTppCur were calculated 1.474 eV and 2.744 eV respectively. Both molecules demonstrated good NLO activities, studied by a Z‐scan approach and additionally with a Differential Four wave Mixing (DFWM) technique. Preliminarily investigations showed that the molecules can be potential optical limiters (OL). These studies divulge the exhibition of a 3‐photon absorption (3PA) mechanism by the synthesized molecules. NLO absorption 3PA coefficient (γ) value of 1.34×10−24 m3/W2, third‐order optical susceptibility (χ(3)) value of 1.543×10−11 esu, and the figure of merit 6.64×10−14 esu was observed for the NiThCur complex and γ=3.61×10−24 m3/W2, χ(3)=1.521×10−11 esu, and FoM=5.61×10−14 esu for NiTppCur with Z‐scan (γ and χ(3)) and DFWM methods, respectively. Normalized transmittance (NT) exhibited a decrease to 78.5 % from 100 % in NiThCur and to 69.5 % in NiTppCur. Optical limiting calculations are also presented. [ABSTRACT FROM AUTHOR]

The sonochemical‐assisted multicomponent reaction catalyzed by ionic liquid, solvent‐free synthesis, improving chemical structure, computational calculations, and nonlinear optical properties (NLO) assessment of a new amidoalkyl naphthol derivative 4, that is, [N‐((2‐hydroxynaphthalen‐1‐yl)(4‐nitrophenyl)methyl)‐2‐phenylhydrazinecarbothioamide (C24H20N4O3S), are introduced. The corrected structure of the synthesized derivative 4 is confirmed by different spectroscopic techniques viz. (1H and 13C) NMR, Infrared radiation (IR), Mass spectra, and UV‐vis. spectra. To obtain geometrical structure and confirm the experimental findings, DFT‐assisted B3LYP/6‐31G* method is used. The NLO properties of the synthesized derivative are studied using two visible laser beams where its nonlinear refraction index (NLRI) at 473 nm cw laser beam is obtained using diffraction patterns (DPs) and the Z‐scan techniques. As high as 5.312×10−11 m2/W of NLRI is obtained. The all‐optical switching (AOS) which is usually carried out utilizing two laser beams, the controlling and controlled, is generalized by the use of three laser beams, controlling, 473 nm beam and two controlled 532 nm and 635 nm beams. [ABSTRACT FROM AUTHOR]

CdTe films, Ag nanoparticles, and Ag/CdTe composites are successfully fabricated on substrates by means of the physical vapor deposition process. The morphological structure, crystal growth and bandgap of the samples are specifically characterized by scanning electron microscopy, X‐ray diffractometer, and UV–vis spectrophotometer. Picosecond (ps) Z‐scan technology is used to investigate the nonlinear optical (NLO) properties of the composites under 532 nm. The results indicate that all samples exhibit saturated absorption nonlinear absorption properties and self‐dispersion nonlinear refraction properties. In addition, Ag nanoparticles can improve the NLO properties of Ag/CdTe composites, and this improvement is more obvious with the increase of Ag power. The results show that the excellent properties of the Ag/CdTe composites are expected to make them an ideal material for use in the photoelectric field. [ABSTRACT FROM AUTHOR]

The covalent organic frameworks (COFs) with olefin linkages are attractive materials for nonlinear optics due to their small energy band gap and large π‐electron separation domain. In this paper, a post‐synthetic modification (PSM) by applying a heck coupling reaction on olefin‐linked COFs was applied for the first time to obtain five functionalized triazine‐based covalent organic framework materials. The synthesized materials were tested for their relevant photophysical and electrochemical properties, and their third‐order nonlinear optical properties were tested using the Z‐scan technique. The experimental results indicate that the post‐modified COF (W4‐2) exhibits third‐order nonlinear polarizability χ3 that is 1.51 times higher than the unmodified COF (W4). [ABSTRACT FROM AUTHOR]

Recently, the preparation of some hematene and magnetene ultrathin non van der Waals (non‐vdW) 2D nanoplatelets was reported starting from hematite and magnetite natural iron ores. The present work reports on the determination and evaluation of the nonlinear optical response and the optical limiting (OL) action of these 2D nanoplatelets dispersed in water under ns laser excitation. The obtained results show that both hematene and magnetene exhibit strong nonlinear absorption and refraction, comparable and even larger than those of other van der Waals (vdW) 2D counterpart materials. In addition, due to their strong nonlinear absorption, both hematene and magnetene show exceptional OL performance from the UV to visible, attaining very low values of optical limiting onset (OLon), comparable and even lower than that of vdW 2D nanomaterials, such as graphene, graphene oxide, other transition metal dichalcogenides like MoS2, WS2 and MoSe2, black phosphorous and antimonene. Moreover, hematene was found to exhibit more efficient OL action than magnetene for all the excitation wavelengths studied, attributed to more efficient ligand to metal charge transfer. The present findings open new possibilities for the potential use of these non‐vdW 2D materials in photonics and optoelectronics, e. g., as optical limiters and optical switchers. [ABSTRACT FROM AUTHOR]

The significance of the anthracene moiety on nonlinear optical (NLO) characteristics is thoroughly examined. The presence of strong electron donor and acceptor groups, large and prolonged conjugation transfer axis, amplifies the push–pull action and increases NLO responses. The values of χ3 obtained for AC derivatives are considerably larger (10−3 esu), indicating that they accurately reflect NLO reactions. According to the optical limiting (OL) investigation, AC has a strong limiting behavior with action beginning at 1.6 KW/cm2. The relationship between transmittance and intensity has demonstrated their potential use in OL applications. Nonlinear optical studies show that all conjugated anthracene chalcones are potential materials for OL devices. [ABSTRACT FROM AUTHOR]

The atomic layer deposition (ALD) technique has attracted significant attention because it enables the control of film synthesis at the subnanometre scale. Herein, molybdenum oxide (MoO3) ultrathin films using the ALD system through Bis(t‐butylimido)bis(dimethylamino)molybdenum (VI) as a molybdenum (Mo) source are prepared. To understand the effect of deposition temperature, thin films are prepared at three different temperatures 100, 150, and 250 °C. The morphological and elemental properties are assessed using a field emission scanning electron microscope, scanning transmission electron microscopy, and energy‐dispersive X‐ray spectroscopy techniques. It is observed that the film thicknesses increase with the increase in the deposition temperature. It is found that the film growth at 150 °C is the most potential one for UV optoelectronic applications with high stability even under low applied bias voltages. Moreover, these films show interesting nonlinear optical behaviors as investigated with the z‐scan technique applying open and closed aperture methods. The calculated nonlinear optical parameters including nonlinear absorption coefficient (β), nonlinear refractive index (n2), nonlinear refractive coefficient (γ), and third‐order nonlinear susceptibility (χ(3)) are 10−11 m W−1, 10−16 cm2 W−1, 10−11 cm2 W−1, and 10−11 esu, respectively. [ABSTRACT FROM AUTHOR]

The curcumin analogues (Cur‐MeS and Cur‐MeO) are synthesized using the 3‐chloroacetyl acetone and aromatic aldehydes reaction. Both compounds are characterized using FTIR, LC‐MS, 1H NMR, and 13C NMR spectroscopies. The geometric optimization and thermodynamic properties of the two compounds are carried out theoretically using DFT. The highest HOMO, lowest LUMO, and Mullikan atom charges of the two compounds are calculated using the B3LYP and CAM‐B3LYP methods which are hybrid functionals with a 6‐311+G(2d,p) as the basis set. The nonlinear optical (NLO) properties of both compounds are studied using the spatial self‐phase modulation (SSPM) through the diffraction ring patterns (DRPs) and the Z‐scan techniques, using a continuous wave (cw) low power 473 nm laser beam. The index of nonlinear refraction (INR) of both compounds is calculated by the two techniques. The all‐optical switching property of both samples is tested using two visible cw laser beams. [ABSTRACT FROM AUTHOR]

Thin graphene oxide (GO) films have been widely explored for their outstanding optical properties, especially their large optical nonlinear coefficients, and high tunability of optical nonlinear coefficients under photoreduction. In this work, an experimental observation of giant nonlinear optical response in GO films under two different photoreduction mechanisms is reported. After ultraviolet (UV) light‐induced photochemical reduction and continuous wave (CW) laser‐induced photothermal reduction, the nonlinear optical response of reduced graphene oxide (rGO) via the Z‐scan method using a femtosecond laser beam at a wavelength of 800 nm is characterized. The rGO exhibits a giant optical nonlinearity, especially two‐photon absorption (TPA). A giant TPA coefficient of rGO on the order of ≈105 cm GW−1 is obtained under two photoreduction mechanisms (photochemistry and photothermal). This is the first time that a large enhancement effect of TPA has been observed in graphene‐based materials, and the TPA coefficient is an order of magnitude higher than the highest value previously reported. The versatile optical nonlinear properties imply a huge potential of the GO film in advanced photonic and optoelectronic devices such as broadband ultrafast optical switching and optical limiting. [ABSTRACT FROM AUTHOR]

Linear and nonlinear optical properties of upper rim Schiff‐base calix[4]arenes are described in this article. Calix[4]arene Schiff‐base derivatives were obtained by reacting tetrakis‐para‐formylcalix[4]arene with appropriate aryl amines (aniline and para‐amino phenol as electrons donor) to extend and to delocalize π electrons system. In this work, the newly synthesized Schiff‐base compounds were characterized by using FT‐IR, 1H, and 13C‐NMR and mass. Linear optical properties of synthesized compounds (2–5) were investigated by UV–Vis spectroscopy and their nonlinear optical properties (NLO) were obtained by the Z‐scan method in ethanol solvent. Results indicated that the synthesized Schiff‐base compounds have a good refractive index (n2) and satisfactory nonlinear absorption index (β), which are suitable for use as well as development of nonlinear materials and nonlinear optical microscopy. [ABSTRACT FROM AUTHOR]

In this study, synthesis, structural, linear, and nonlinear optical properties of L‐valine capped Zn doped MgO nanoparticles (NPs) are reported. L‐valine capped (15 mol%) MgO NPs doped with Zn (1, 2, and 5 wt%) are obtained by chemical co‐precipitation method and are calcined at 500°C for 2 h. X‐ray diffraction (XRD) pattern shows major reflections at 2θ = 42.91°, 62.11°, and 78.34° corresponding to (200), (220), and (222) planes of MgO with a face‐centered cubic structure, respectively, and the average particle size is found to be 13 nm. Surface morphology is studied using HR‐TEM and energy dispersive X‐ray spectroscopy (EDS) attests the purity of prepared samples. Utraviolet‐visible (UV‐vis) spectroscopic studies of both uncalcined and calcined samples attest the formation of NPs and strong blue shift in the excitonic absorption has been observed. Samples have been characterized for third‐order nonlinear absorption using open aperture z‐scan technique under continuous wave (CW) He‐Ne laser and are found to exhibit strong nonlinear absorption coefficient due to thermal effect. [ABSTRACT FROM AUTHOR]

The structural, optical, and nonlinear optical absorption properties of ZnO polycrystalline thin films are investigated. Energy bandgap values are obtained with linear absorption spectrum and depending on either sole doping of Al or co‐doping, bandgap energies shift toward higher or lower energies. With Al‐only doping, bandgap of the ZnO thin film shifts toward higher energies which can be attributed to Moss–Burstein effect, and with co‐doping (Al–Cu or Al–Co) bandgap energies shift toward lower energies due to defect states residing within the bandgap. Urbach energies and grain sizes are calculated to study the effect of defect states on the nonlinear absorption, and these calculations indicate that co‐doping drastically reduces the grain size thereby increasing the contribution to the defect density by means of boundary defects. To analyze the transmission in open aperture Z‐scan data, a theoretical model incorporating one‐photon, two‐photon, and free‐carrier absorptions as well as their saturations is used. By this modeling, saturation intensity thresholds and effective nonlinear absorption coefficients are extracted from fitting of the experimental data. Highest saturation intensity threshold and effective nonlinear absorption coefficient are found for ZnO:(Al, Co) and ascribed to having the smallest bandgap energy and highest Urbach energy. [ABSTRACT FROM AUTHOR]

The research work is devoted to study the influence of annealing temperature on the structural and optical properties of ZnSe thin films. The samples are prepared by a thermal evaporation technique and part of the as‐deposited films are annealed. X‐ray diffraction patterns and Raman spectra analysis reveal that the ZnSe thin films have cubic zinc‐blende crystal structure and the crystallinity increases as the annealing temperature increases. For the linear optical parameters, the absorption edge moves to shorter wavelengths with the increase of annealing temperature. Based on Swanepoel's method, the refractive index, film thickness, absorption coefficient and optical band gap are determined. The values of band gap are found to increase from 2.63 to 2.68 eV as the annealing temperature increases. By performing an open aperture Z‐scan technique with femtosecond pulses under 800 nm wavelength, all ZnSe samples show two‐photon absorption responses. It is found that the modulation depth and the two‐photon absorption coefficient decrease with increasing annealing temperature. Moreover, all samples exhibit better optical limiting responses at higher incident power intensities. These novel properties render this a promising material for traditional optoelectronic devices and optical limiters. [ABSTRACT FROM AUTHOR]

Functional group and position isomers of azo and azomethine were selected to investigate their effect on linear and NLO properties. The azo and azomethine analogs show absorption maxima in the range 460–500 nm and 375–435 nm respectively. They are emissive in green, orange to the deep red region with a large Stokes shift of 100–200 nm. When we compared azo and azomethine chromophores i. e. functional group isomers, azo chromophore shows a bathochromic shift of 50–103 nm, while in case of position isomers azo and azomethine having larger conjugation effect i. e. VA‐2 and VI‐2 show a more bathochromic shift of 28 nm and 42 nm than the corresponding analogs VA‐1 and VI‐1, which show respectively 466 nm and 379 nm. Band gaps evaluated by electrochemical method and DFT method are correlated with the bathochromic shift in absorption maxima. The dyes are thermally stable (up to 280 °C). Open and closed aperture Z‐scan techniques were used to evaluate the third order non‐linear optical (NLO) parameters ‐ nonlinear absorptive coefficient (β), nonlinear refractive index (η2), and third order non‐linear optical susceptibility (χ (3)). NLO properties were theoretically calculated by using DFT method with six different functionals. Mean absolute error (MAE) and standard deviation (SD) were evaluated to get more insight into theoretical calculation. With the set of calculated data points, MAE and SD calculated to check performance of the DFT functional. Different functionals were used to evaluate vertical excitation values and compared it with experimental absorption maxima. [ABSTRACT FROM AUTHOR]

We explore the third‐order optical nonlinear properties of arsenic‐ and germanium‐free chalcogenide glasses (ChGs) within a gallium‐tin‐selenium (Ga‐Sn‐Se, GSS) ternary system at wavelength of 1.064 μm in the picosecond region. A classical characterization showing the values of the absorption and the linear index will be given. Then, using D4σ‐Z‐scan technique, both nonlinear refractive index (n2) and nonlinear absorption coefficient (β) of the GSS ChGs will be measured. A comparison of the results is made with other families of chalcogenide glasses considering the figure of merit calculation. The first results show that GSS system would give better NL performance promising high potential for n2(β)‐based photonic devices performed under clean production and green/sustainable chemistry. [ABSTRACT FROM AUTHOR]

Nonlinear‐optical refraction is typically described by means of perturbation theory near the material's equilibrium state. Graphene, however, can easily move far away from its equilibrium state upon optical pumping, yielding strong nonlinear responses that cannot be modeled as mere perturbations. So far, one is still lacking the required theoretical expressions to make predictions for these complex nonlinear effects and to account for their evolution in time and space. Here, this long‐standing issue is solved by the derivation of population‐recipe‐based expressions for graphene's nonperturbative nonlinearities. The presented framework successfully predicts and explains the various nonlinearity magnitudes and signs observed for graphene over the past decade, while also being compatible with the nonlinear pulse propagation formalism commonly used for waveguides. [ABSTRACT FROM AUTHOR]

Femtosecond laser excitation (800 nm, ∼150 fs, 80 MHz) induced anisotropic nonlinear optical behaviour and optical limiting action of ethylenediamminium picrate (EDAPA) crystal along two prominent orientations (2 0 0) and (1 1 1) was studied using the Z‐scan technique. EDAPA exhibited reverse saturable type nonlinear absorption ascribed to two‐photon absorption (2PA) process and self‐defocusing based on nonlinear refraction. Intensity dependent nonlinear absorption studies portray the 2PA coefficient is independent of the peak intensity of excitation. Frontier molecular orbitals studies revealed the non‐availability of real states at laser excitation (1.55 eV) and the measured energy gap of 3.18 eV avails the energy states for simultaneous absorption of two photons involving virtual states leading to the occurrence of genuine 2PA. In addition, using molecular electrostatic potential (MEP) analyses polarizability (5.30×10−24 esu) and dipole moment (7.317 Debye) were calculated using the density functional theory. A variation in the NLO coefficients with respect to orientation of excitation arises due to the anisotropy of the crystal. EDAPA crystal along (1 1 1) orientation has high laser damage threshold (9.1 GW/cm2) and low optical limiting threshold (24.36 μJ/cm2) and thus the wide dynamic range make it a preferred candidate towards laser safety devices for high repetition rate ultrashort laser pulse excitation. [ABSTRACT FROM AUTHOR]

The non‐linear and linear optical properties of 2‐napthol based four monoazo dyes were examined by computational and Z‐scan methods. Time‐dependent (TD)‐density functional theory (DFT) computations were used to evaluate the linear polarizability (α), first‐order hyperpolarizability (β) and second‐order hyperpolarizability (γ) using global hybrid and range separated hybrid functionals at 6–311+ G (d) basis set. The functional, ωB97 performed better in the determination of linear polarizability (α) and ωB97X−D performed better in the determination of the first‐order hyperpolarizability (β) and second‐order hyperpolarizability (γ) among the global hybrid and range separated hybrid functionals. To support our theoretical findings for α, β, and γ, we have correlated with the Hammett‐coefficient (σ), excited state coefficient (σex) as well as by hyper‐hardness (Γ) relations. Third order NLO parameters – non‐linear refractive index (η2), non‐linear absorption coefficient (β), real parts and the imaginary parts of third order susceptibility (χ(3)), and second order hyperpolarizability (γ) were investigated by close and open aperture methods using Z‐scan technique. The –NO2 substituted dye 2 shows higher value of molecular susceptibility (χ(3)), polarizability (α), and hyperpolarizability (β, γ) parameters among the studied azo dyes. They are likely to have potential applications in optoelectronics and photonics. [ABSTRACT FROM AUTHOR]

NLOphoric D‐π‐A‐π‐D coumarin chalcone 5 and their BF2 complex 6 were designed, synthesized and characterized through Mass,13C‐NMR, and 1H‐NMR analysis. Their Photophysical properties are extensively studied in solvents of different polarity. On BF2 complexation of coumarin chalcone shows highly red shift in absorption and emission spectra compared to uncomplexed coumarin chalcone. Positive solvatochromism observed which is well supported by linear and multilinear regression analysis. For BF2 complexed coumarin‐chalcone 6 the solvent dipolarity (CSdP) is the main factor responsible for slightly red shift in absorption spectra, and also for the highly red‐shift in emission spectra. Frontier molecular orbital, molecular electrostatic potential and Generalized Mulliken‐Hush analysis revealed intramolecular charge transfer in these compounds. Nonlinear optical (NLO) properties for compounds 5 and 6 were studied by solvatochromic and computational method. The linear polarizability (α), first‐order hyperpolarizability (β) and second‐order hyperpolarizability (γ) of compounds were studied by the time dependent density functional theory using three different functionals namely B3LYP, BHHLYP and CAM−B3LYP with the 6–31 G (d) basis set. BF2 complexed compound 6, show higher values for αe + αv as well as βe+βv compared to compound 5. Third order nonlinear optical susceptibility (χ(3)) of these compounds obtained by Z‐scan analysis. Third‐order (χ(3)) non‐linear optical properties of BF2 complexed coumarin‐chalcone 6 were observed to be several times higher than those of the uncomplexed coumarin‐chalcone 5 these justify the design approach. [ABSTRACT FROM AUTHOR]

Quinoxaline derivative QY 54 A, an analog of commercially available C.I. (Colour index) Disperse Yellow 54 (quinoline derivative) is synthesized and confirmed by 1H, 13C NMR, LC–MS, and CHN analysis. It is emissive (512 nm) with a quantum yield (ϕF) =0.34. The electrochemical properties of both the dyes were investigated using cyclic voltammetry (CV). The titled dyes are thermally stable (up to 350 °C). A comprehensive study of linear and nonlinear optical (NLO) properties of commercial dye (QY 54) and its analog (QY 54 A) are performed by Z‐scan and Density functional theory (DFT). The NLO (βo, γo) values obtained are compared with the NLO (βo, γo) values of urea. Ten different functionals are used to see the effect of %Hartree Fork (HF) exchange on computed NLO properties of both the dyes. The functional M06‐HF (100% HF) and ωB97 (0‐100% HF) perform better for evaluating NLO properties. The Z‐scan and DFT result reveal that QY 54 A and QY54 are excellent NLOphores. The stability and enhancement in NLO properties of QY 54 A are due to electrophilicity index (ω), the Intramolecular charge transfer (ICT) character is confirmed by HOMO‐LUMO study (2.19 eV), quinoid character (0.0230 A°) and molecular electrostatic potential (MEP) plots. An analog of CI disperse yellow 54 (QY 54) is synthesized, characterized and labelled as QY 54 A. QY 54 is non emissive whereas QY 54 A is emissive. The NLO property of both the dyes is evaluated using DFT and Z‐scan method. Both the dyes are thermally stable and exhibit electrochemical property. The charge transfer property and stability of both the dyes is determined by experimental and DFT method. [ABSTRACT FROM AUTHOR]

Abstract: Small‐sized potassium dihydrogen phosphate (KDP) samples cut from the pyramid sector of a large KDP boule are observed to have different impurity content. The nonlinear absorption properties of two KDP samples containing different impurities are characterized by Z‐scan technique with picosecond laser at 355 nm wavelength. Reverse saturable absorption effects are found in samples, with nonlinear absorption coefficients of 7.35 × 10−2 cm GW−1 and 15.91 × 10−2 cm GW−1. The sample with more impurity contents exhibits stronger nonlinear absorption. Such behavior is considered to be a result of nonlinear energy coupling under 355 nm laser irradiation assisted by impurity defects. Nanosecond laser‐induced damage test at 355 nm of the two KDP samples is further investigated. The bulk damage thresholds of the two samples are 4.7 and 0.423 J cm−2 respectively, indicating that impurity‐induced nonlinear absorption might play an important role in laser‐induced damage processes. [ABSTRACT FROM AUTHOR]

Abstract: A new inorganic nonlinear optical single crystal of sodium cadmium tetra chloride (SCTC) is successfully grown from aqueous solution by the slow evaporation technique at room temperature. The crystalline nature of the grown crystal is analyzed by powder X‐ray diffraction. The lattice parameters and crystal system is confirmed by single crystal X‐ray diffraction. Optical transmission study on SCTC crystal shows high transmittance in the entire UV–Vis region. The mechanical strength of the grown crystal is estimated by Vicker's microhardness test. The second harmonic generation (SHG) efficiency of the crystal is measured by Kurtz's powder technique infers that the crystal has nonlinear optical (NLO) efficiency 1.75 times that of KDP. The variation of dielectric constant and dielectric loss as a function of log frequency at various temperature reveals that the crystal shows normal dielectric behaviour. The growth process of SCTC crystal is analysed by etching study. The features of surface of grown crystal is analysed by SEM/EDAX spectrum. The third order nonlinear optical property is investigated for the grown crystal by z – scan technique and the results indicates that SCTC crystal should be a promising material for nonlinear optical device applications. [ABSTRACT FROM AUTHOR]

The optical limiting properties of a series of near infrared absorbing 3,5-dithienylenevinylene BODIPY (boron-dipyrromethene) dyes ( 1- 3) that contain donor and acceptor moieties in their π-conjugation systems were studied by using the z-scan technique at 532 nm in the nanosecond pulse range. A strong reverse saturable absorption response was observed when the compounds are embedded into poly(bisphenol carbonate A) polymer thin films, which demonstrates that BODIPY dyes with this type of structure are suitable for use in optical limiting applications. [ABSTRACT FROM AUTHOR]

The stabilization of black phosphorous quantum dots (BPQDs) for optical application under ambient conditions is highly challenging. Here, a facile approach is presented to substantially stabilize BPQDs by making a uniform BPQDs/polymethyl methacrylate (PMMA) composite nanofiber film via an electrospinning technique. As verified by femtosecond laser Z-scan measurement, the BPQDs/PMMA composite nanofiber film that has been stored for three months exhibits almost the same nonlinear optical properties as the fresh BPQDs. Additionally, the BPQDs/PMMA composite nanofiber film demonstrates broadband nonlinear optical response ranging from the visible bandwidth (400 nm) to the mid-IR bandwidth (at least 1930 nm). By employing the BPQDs/PMMA composite nanofiber film as an optical saturable absorber, an ultrashort pulse with the pulse duration of ≈1.07 ps centered at the wavelength of 1567.6 nm is generated in a mode-locked fiber laser. These results suggest that the BPQDs/PMMA composite nanofiber film can combine the advantage of convenient integration and mitigation of the drawback of the easy oxidation of black phosphorous and pave the way for BP-based practical optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this paper, we present synthesis of amino acids ( l-arginine and l-alanine) assisted surface modification of ZnO nanoparticles (NPs) using chemical precipitation method. Study emphasizes the utility of l-arginine over l-alanine in the synthesis process and ZnO NPs with average particle size of 18 nm have been successfully obtained using l-arginine. Structural properties were evaluated using powder X-ray diffraction (XRD) pattern, energy dispersive X-ray spectroscopy (EDAX) and transmission electron microscopy (TEM) that confirmed the purity, surface morphology and hexagonal wurtzite crystal structure of ZnO NPs. Linear optical studies using ultraviolet-visible (UV-vis) spectroscopy and Fourier transform infra-red (FT-IR) spectroscopy indicated the blue shift of excitons absorption wavelength and surface modification by amino acids. Blue shifting is more prominent for l-arginine and optical band gap of 3.48 eV has been achieved in the present case. Third order nonlinearity (nonlinear refraction and absorption) of ZnO NPs embedded in polyvinyl alcohol (ZnO-PVA colloidal suspension) was studied by Z-scan technique at wavelength 632.8 nm in continuous wavelength regime which shows negative nonlinearity with self-defocusing effect. Large value of n2 and β were obtained in case of ZnO NPs passivated by l-arginine and effect was attributed to thermal lensing. Thermally stimulated third order nonlinear susceptibility ( x(3)) for ZnO-PVA colloids have also been calculated and presented. [ABSTRACT FROM AUTHOR]

Purpose: Upon irradiation the active diacetylene layer of radiochromic films undergoes dose-dependent polymerization in the blue polydiacetylene form. Dose assessment is currently based on linear absorbance measurements. The scope of the present study was designed for the further understanding of the linear and, in particular, the nonlinear optical characteristics of such films and the utilization of these characteristics for devising alternative 'reading' procedures. Methods: The nonlinear optical interactions of laser light with previously irradiated GafChromic® HD-810 and MD55-2 films were studied by z-scan techniques. The focused laser beam strikes on the film, which is located at various distances from the focal spot. The beam induces linear and nonlinear absorption and refraction. The measurement of the transmitted power (open-aperture z-scan) allows the study of the nonlinear absorption. On the other hand, the measurement of the axial region of the transmitted beam (closed-aperture z-scan) is related to both nonlinear absorption and refraction effects. A 10 mW, 633 nm, linearly polarized He/Ne laser was employed as the light source. The transmittance measurements were coupled with absorbance measurements carried out over the whole visible spectrum and at various reading temperatures, in an attempt to clarify the underlying mechanisms dictating the observed effects. These effects were incorporated to an open-aperture z-scan model, developed for the purpose of comparison to the corresponding experimental curves. Results: The transmittance data obtained by both open- and closed-aperture z-scan were found to be dose-dependent, thus allowing such transmittance techniques to be employed for dose assessment. Low power open-aperture z-scan measurements (sensitive to absorptive nonlinearities) revealed a stepwise two-photon excitation of the active layer, through an intermediate state. At higher laser intensities (and/or absorbed dose), the shapes of the z-scan curves were found to be more complicated. These shapes were attributed to a temperature-dependent (thermochromic) transition from the blue form to the conformer red form of the active material, a transition which appears to be irreversible at high intensities. This transition was incorporated into the open-aperture z-scan model which reproduced satisfactorily the corresponding experimental curves. Finally, the use of a chopped laser beam in the closed-aperture z-scan technique allowed artifact-free, high spatial resolution dose measurements using a laser beam of relatively high power. Conclusions: The model developed in the present study elucidates some of the effects related to film reading and the causes of some of the artifacts reported in the literature. Two-dimensional dose distributions can be assessed by z-scan; however, the merits of such a technique relative to those currently in use have to be further investigated. [ABSTRACT FROM AUTHOR]

Three-photon absorption (3PA) properties of symmetric-type carbazole derivatives show great potential for application in light-activated therapy and optical limiting. A novel symmetrical carbazole derivative (abbreviated as POCP) with end-groups of 1,10-phenanthroline rings as the donor moieties, chained via carbon-nitrogen (C = N) double bond, has been synthetized and its three photon absorption properties has been also determined by using a Q-switched Nd: YAG laser pumped with 30 ps pulses at 1064 nm in dimethylformamide. The measurement of 3PA cross-section of this compound is performed by open aperture Z-scan and σ3PA is 481 × 10-78 cm6 • s2/photon2 for the transition S0 → S1. The influence of the molecular structure of this compound on three-photon absorption cross-sections is discussed micromechanically by Austin model 1 and Zerner's Intermediate Neglect of Differential Overlap/S method. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The frontal polymerization (FP) of bisphenol A ethoxylate diacrylate (BPAEDA) was carried with and without the presence of two different azobenzene comonomers by means of an external heating source. The first azomonomer (MDR-1) is a derivative of disperse red-1, N-ethyl- N-(2-hydroxyethyl)-4-(4-nitrophenylazo)aniline, whereas the second (E)-2-(4-((4-nitrophenyl)diazenyl)phenyl)-5,8,11-trioxa-2-azatridecan-13-yl methacrylate (4PEGMAN) comes from the azo-dye N-methyl- N-{4-[(E)-(4-nitrophenyl)diazenyl]phenyl}- N-(11-hydroxy-3,6,9-trioxaundecas-1-yl) amine. In this work, an ionic liquid trihexyltetradecylphosphonium persulfate was used as initiator. This compound produced stable propagating polymerization fronts with good velocities and moderate maximum temperature values. Moreover, this initiator prevented bubble formation and was found to be the most efficient when it was used in lower amounts with respect to other initiators, such as benzoyl peroxide, 2,2′-azobisisobutyronitrile, aliquat persulfate®, and tetrabutylphosphonium persulfate. The thermal properties of the obtained polymers and copolymers were determined by thermogravimetric analysis and differential scanning calorimetry. The nonlinear optical (NLO) characterizations of the developed BPAEDA/MDR-1 and BPAEDA/4PEGMAN copolymers were performed according to the Z-Scan technique in film samples prepared by classical polymerization. It has been proven that samples with higher 4PEGMAN content (0.26 mol %) exhibited outstanding cubic NLO-activity with positive NLO-refractive coefficients in the promising range of n2 = +3.2 × 10−4 esu. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

We investigated the third-order nonlinear optical properties of donor-acceptor substituted hydrazones doped into PMMA matrix using single beam Z-scan technique at 532 nm. The magnitude of third-order susceptibility, χ(3) is of the order of 10-13esu. The nonlinear refractive index, n2 and the molecular second order hyperpolarisability, γh are of the order of 10-11esu and 10-32esu, respectively. The compounds exhibit larger third-order NLO properties in PMMA host when compared to the pure compounds. The study reveals that these hydrazones are a good candidate of nonlinear optical materials for photonic applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Summary A sandwiched 15 nm AgOx thin film of the super-resolution, near-field optical disk was studied using a confocal Z-scan system. Nonlinear optical properties of quartz glass/ZnS–SiO2 (170 nm)/AgOx (15 nm)/ZnS–SiO2 (40 nm) were measured using a Q-switch Nd : YAG pulse laser of wavelength 532 nm, pulse width 0.7 ns, and 15.79 kHz repetition rate. Transmittance and reflectance of the sandwiched AgOx thin film show important optical responses at the focused position of Z-scan. The dissociation processes of AgOx , recombination of the silver and oxygen, and the resonance of the localized surface plasmon of the nano-composites of the AgOx thin film are correlated to transmittance and reflectance at the focused position of the Z-scan for different input laser powers. An irreversible upper threshold intensity of 4.40 × 106 mW cm-2 at the focused position was found. A reversible working window of the focusing intensity between 1.86 × 106 and 4.40 × 106 mW cm-2 was measured with sandwiched AgOx thin film alone. The near-field interactions of the AgOx thin film and the recording layers of super-resolution near-field optical disk are also discussed. [ABSTRACT FROM AUTHOR]

Wide‐spectral saturable absorption (SA) has been experimentally demonstrated in two‐dimensional (2D) nanomaterials with outstanding performance, such as low saturation intensity, deep modulation depth, and fast recovery time of excited carriers. Hence, 2D nanomaterials can be utilized as saturable absorbers for mode‐locking or Q‐switching to generate laser pulses with short duration and high repetition rate. Here, the SA properties of graphene, layered transition metal dichalcogenides, Group‐V elements, and other 2D nanomaterials are reviewed by summarizing their slow‐ or fast‐ saturable absorption behavior using the modified Frantz–Nodvik model or the steady‐state solution of Hercher's rate equations. The dependence of SA in 2D nanomaterials on excitation wavelength, linear absorption coefficient, and pulse duration is also explained. Finally, the applications of these 2D nanomaterials in a range of pulsed lasers are summarized. [ABSTRACT FROM AUTHOR]

In article number 1702437, Zhouguang Lu, Han Zhang, and co‐workers present a method to stabilize black phosphorus quantum dots (BPQDs). BPQDs/polymethyl methacrylate (PMMA) composite nanofiber film, made via an electrospinning technique, preserves nonlinear optical properties similar to just‐prepared BPQDs even after three months storage. [ABSTRACT FROM AUTHOR]