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Niobium telluride (NbTe2), a kind of few-layer two-dimensional (2D) transition metal dichalcogenides (TMDs) material, has been theoretically predicted with nonlinear absorption properties and excellent optical response. Herein, we experimentally demonstrated an Er-doped fiber (EDF) laser based NbTe2 as saturable absorber (SA). Few-layer NbTe2 nanosheets were successfully prepared by adopting the commonly used liquid-phase exfoliation (LPE) method. The nonlinear optical response of highly stable few-layer NbTe2 was investigated through an open-aperture Z-scan laser measurement, the nonlinear absorption coefficient was 2.45 × 10−11 m/W. Both Q-switched and mode-locked operation centered at 1 559 nm were recorded based on NbTe2 SA. The pulse duration was varied from 4.88 μs to 1.75 μs, and the adjustable range of repetition frequency is changed from 44.01 kHz to 64.12 kHz in passively Q-switched operation. Furthermore, a constant repetition rate of 5.33 MHz and pulse width of 2.67 ps were observed in mode-locked operation. Our experimental results fully reveal the nonlinear optical properties of NbTe2 used in pulsed fiber lasers and broaden its ultrafast applications in the optics field.

This paper presents the effects of incorporating thienyl and phenyl rings as the terminal ring in the cinnamoyl counterparts of chalcones with donor-acceptor-donor (D-A-D) push-pull setting, on their photophysical responses. Two fluoro-methoxy substituted chalcone derivatives with distinct cinnamoyl systems, 4-methylthiophene-2-carbaldehyde (2F4MA48) and 2,4-dimethylbenzaldehyde (2F4MA96), were synthesized. Characterization of these chalcone derivatives was performed using nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR) and single-crystal X-ray diffraction (SCXRD). Comparative studies on the linear and nonlinear optical responses were carried out through both experimental analyses and theoretical density functional theory (DFT) calculations. The electronic absorption spectra computed using DFT were compared with the UV-Vis spectra to elucidate the intramolecular charge transfer mechanism via the hole-electron distribution and interfragmentary charge transfer analyses. Molecular properties were examined through electrostatic potential (ESP) maps, π-electron localization function (ELF-π), and frontier molecular orbitals (FMOs). The incorporation of thienyl ring is found to give a stronger push-pull effect and greater electron delocalization. Experimental nonlinear optical responses were investigated using Z-scan technique with a continuous-wave incident laser at a wavelength of 532 nm. Both compounds showed two-photon-induced reverse saturation absorption (RSA) and self-defocusing responses. It was observed that the thienyl-based chalcone, exhibited greater optical nonlinearity in terms of nonlinear absorption (NLA), nonlinear refraction (NLR), and optical limiting. The experimental third-order nonlinear optical susceptibility (χ(3)) was determined to be 8.04 × 10−8 esu for 2F4MA48 and 1.08 × 10−8 esu for 2F4MA96. The onset limiting threshold (FS) was found to be 2.63 kJ cm−2 for 2F4MA48 and 5.23 kJ cm−2 for 2F4MA96. The steep optical limiting traces of 2F4MA48 show superior performance compared to 2F4MA96.

In this work, the photothermal nonlinearity within a layered bismuth telluride (Bi2Te3) is studied in detail. The dynamics of the optical nonlinearity with increasing photothermal effect are investigated via pump-probe spectroscopy. The difference between the thermally-induced and photon-induced nonlinearities was clarified and the entire photothermal nonlinearity was therefore sketched. Furthermore, by removing the thermally-induced background signal, the n2 without accumulated heat can then be estimated. For example, the n2 value is 2.80 × 10−8 cm2/W at a peak intensity of 12.81 MW/cm2. The results are compared with those obtained from another measurement to validate the reliability of the estimation. The working range of the n2 value is also discussed. To provide further validation of the feasibility of the proposed method, the photothermal nonlinearity within monolayer graphene is provided and discussed. This work provides an alternative method to deal with optical nonlinearity measurements that are subject to the photothermal effect, paving the way toward further related research.

Nonlinear optical properties of metallic and oxide metallic nanoparticles have been extensively studied as saturable absorbers in fiber-optic lasers in the infrared region for the generation of short and/or ultrashort pulses. In this paper, we report an experimental study of the nonlinear optical response of silver and zinc nanoparticles for continuous-wave illumination at 1550 nm. Nonlinear absorption was investigated using the power-dependent transmission and Z-scan techniques. The results obtained from the first technique showed that the zinc and silver particles behave like saturable absorbers, the modulation depths obtained were 15 % and 32 %, respectively. The Z-scan technique showed the presence of nonlinear refraction and absorption in both samples, the open aperture configuration confirmed the behavior of the materials as saturable absorbers. Additionally, the nonlocality of the nonlinear response was analyzed using a numerical model.

Heat transfer is an important process in many engineering applications, including materials science and photonics. We present a Z-lambda software tool for the simulation of heat transfer in transparent solids during laser irradiation, using the heat equation and an explicit difference method. The software allows for the simulation of laser heating scenarios, including the modeling of pulsed laser heat sources. The software is able to calculate heat transfer in any isotropic transparent solid materials. It can be used to simulate the heat transfer caused by laser radiation during Z-scan experiments, by calculating the temperature distribution of the sample. The software is written entirely in C++, and it is designed to be run in a terminal. It can utilize up to 64 processor threads to perform calculations, making it a powerful tool for the simulation of complex heat transfer scenarios. Overall, this software provides a valuable tool for the modeling and simulation of heat transfer in transparent solids, and it can be used in various engineering applications. The software is available for download and use under an open-source license.

Transparent conducting metal oxides (TCOs) are well known for their application in optoelectronic devices. However, the nonlinear optical (NLO) study of TCOs helps to understand the characteristic features which give insight into their practical utilization as well as device application in each optical spectrum. In this work, we studied the structural, electrical, optical, and nonlinear optical properties of Sn-doped CdO. The structural, electrical, optical, and nonlinear optical properties of Sn-doped CdO were studied by using an X-ray diffractometer (XRD), Hall measurement system, UV–vis spectrometer, and Z-scan measurement. The XRD analysis shows that Sn-doped CdO is a polycrystalline material with a preferential peak of a plane (111) shifting slightly toward the (200) plane as Sn doping suddenly increases. Sn-doped CdO proved good electrical properties with conductivity increase from 0.192 × 102 Ω−1 cm−1 to 2.03 × 102 Ω−1 cm−1 and decrease in resistivity from 52.1 × 10−3 Ωcm to 4.92 × 10−3 Ωcm as the molar dopant concentration increase from 0.0001 M to 0.0005 M. The obtained bandgap for undoped and 0.0005 M, 0.0004 M, 0.0003 M, 0.0002 M, 0.0001 M Sn-doped CdO are 2.37, 1.63, 1.70, 1.81, 1.86, and 2.09 respectively. The NLO absorption coefficient (β) for 0.0003 M, 0.0004 M and 0.0005 M are 6.31 × 10−3 m/W, 11.47 × 10−3 m/W and 10.6 × 10−3 m/W respectively.

Optoelectronic and the cubic nonlinear optical properties of 4-(4-Bromophenyl)-2-(4-nitrophenyl)-2, 3-dihydro-1H-1, 5-benzodiazepine have been studied. Z-scan technique was used for the third-order nonlinear optical measurements namely, nonlinear absorption, nonlinear refraction, and optical power limiting behaviour employing an Nd: YAG laser of 532 nm wavelength having 5 ns Gaussian pulses. B3LYP/6–311 ++ G (d, p) level of theory was employed for structural optimization, vibrational wavenumber, frontier molecular orbitals, natural bond orbital and population analysis. The MOLVIB programme was used to perform unambiguous vibrational assignments based on potential energy distribution values acquired from normal coordinate analysis. B3LYP and CAM-B3LYP hybrid functions have been employed at the DFT level to calculate the theoretical second-order hyperpolarizability. The substitution of –NO2 and -Br in this benzodiazepine compound enhances the second-order hyperpolarizability (γ) to the order of 10−34 esu and, switching of self-defocussing to self-focussing phenomenon. The HOMO-LUMO and optical band gap analysis illustrates that polarizing nature of the molecule vary with substituents. The obtained results indicate that this compound has potential applications in optoelectronics and photonics.

The Z-Scan technique is an easy and widespread approach to evaluate the nonlinear optical coefficient of materials. However, the evaluation of the same coefficients for thin films requires complex experimental setups that allow to remove the contributions of the substrate. Here, we propose a simple, yet effective, theoretical approach that allows to include the substrate contribution to the focusing effect when scanning along the propagation axis. The proposed method therefore removes the need of complex experimental setups and paves the way for a simpler retrieval of optical properties of complex nanostructures.

This article describes a dataset of synthetic images representing biological scenery as captured by a Fourier Lightfield Microscope (FLMic). It includes 22,416 images related to eight scenes composed of 3D models of objects typical for biological samples, such as red blood cells and bacteria, and categorized into Cells and Filaments groups. For each scene, two types of image data structures are provided: 51 × 51 Elemental Images (EIs) representing Densely Sampled Light Fields (DSLF) and 201 images composing Z-Scans of the scenes. Auxiliary data also includes information about camera intrinsic and extrinsic calibration parameters, object descriptions, and MATLAB scripts for camera pose compensation. The images have been generated using Blender. The dataset can be used to develop and assess methods for volumetric reconstruction from Light Field (LF) images captured by a FLMic.

We report the third-order nonlinear optical (NLO) properties of ZnO@C-N composite microspheres and pure ZnO which have been investigated with the Z-scan technique under continuous wave laser. ZnO@C-N composite microspheres have been hydrothermally synthesized at two different precursor concentrations to have structures at different impurity levels. Moreover, pure ZnO is prepared under the annealing process. The nonlinear optical absorption of samples was measured by using the open-aperture Z-scan technique and was evaluated relating to the two-photon absorption (TPA) mechanism. Moreover, both ZnO@C-N and ZnO microstructures exhibited a negative nonlinear refractive index (NLR) referring to the self-defocusing effect. The order of the (NLR) value, is about 10 -10 (cm 2 /W) and, the NLA coefficients of specimens are in the order of 10 -5 (cm/W). The NLA coefficient has a similar behavior as the NLR versus increasing incident intensity of the laser. The results show that the nonlinearity response of ZnO@C-N composites is higher than the pure ZnO and ZnO@C-N at higher precursor concentrations exhibits the maximum amount of NLA and NLR coefficients compared to other samples. This observation which is attributed to the change in optical and structural properties of material due to impurity presence, underscores the presence of impurity for engineering materials to improve the nonlinearity properties., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this article, the structural and nonlinear optical behaviour of a chalcone derivative, (2E)-1-(4-ethoxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one have been studied. FT-IR, FT-Raman, and NMR spectroscopy were analyzed to validate the molecular structure. To predict the nonlinear optical characteristics of the chalcone, the DFT approach was used and the experimental results were corroborated by the computations. The bathochromic shift is obtained in linear absorbance spectra and is validated using TD-DFT. Also, the broad emission in the blue region demonstrates the blue light emission property of the sample. Using the finite-field method, the dipole moments, polarizability, first-order and second-order hyperpolarizability parameters have been computed. Ground and excited state dipole moments were quantified by solvatochromism. The third-order nonlinear optical characteristics of chalcone in polar and non-polar solvent media were examined using the open/closed-aperture z-scan technique. The chalcone displayed considerable two-photon absorption with a positive nonlinear absorption coefficient and a positive index of refraction due to the self-focussing effect. Furthermore, the optical limiting study manifests that the investigated chalcone might well be favourable for NLO applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A nonlinear optical single crystal of bis (cytosinium) tartarate monohydrate (BCTM) was grown by slow evaporation method at room temperature. Single crystal X-ray diffraction study revealed their cell parameters and corresponding space group. Different functional groups were identified by using FTIR spectral analysis. Phase purity of the grown crystal was analysed by chemical etching and powder X-ray diffraction studies. The mechanical strength of the grown crystal was estimated using Vickers microhardness test. The thermal stability of the grown crystal was investigated by TGA-DTA studies. The optical absorption study was carried out in the wavelength range of 190–1100 nm. The dielectric response of the grown crystal was studied as a function of frequency at different temperatures. Second harmonic generation efficiency (SHG) was measured by Kurtz and Perry powder technique. The Z-scan pattern clearly evidenced that the BCTM exhibits sequential two photon absorption induced reverse saturable absorption.

Undoped CdO films and three different molarities of cadmium oxide (CdO) films were doped with fluorine on glass slides via a chemical spray pyrolysis method. The samples were analyzed using X-ray diffractometry (XRD), scanning electron microscopy (SEM), UV–VIS-NIR spectroscopy, electrical measurements, and Z-scan measurements. XRD measurement revealed better crystallinity with preferred orientation at [111] plane. Nanospheres of varying sizes were obtained from the surface micrographs. The direct band gap energy decreased as the fluorine concentration increased. The film resistivity recorded a decline with increased carrier mobility as the flourine concentration increased. The nonlinear optical absorption coefficient (β) gotten for 0.0003 M, 0.0004 M, and 0.0005 M at 632.8 nm wavelength are 3.83×10–3 m/W, 5.7 × 10–3 m/W and 5.48×10–3 m/W respectively. The deposited films find potential application in solar cell and optoelectronic devices.

We present non-linear optical properties of graphene oxide (GO) doped with low chirality metallic single walled carbon nanotubes (m-SWCNTs) thin films. The weight percentage of the m-SWCNTs was 5, 10, and 20 wt%. High-resolution transmission electron microscope (HRTEM), high resolution scanning electron microscope (HRSEM), Raman, and UV–vis spectroscopy were used to characterize the prepared samples. We have investigated their nonlinear optical properties using open and closed Z-scan technique at Nd:YAG laser at 1064 nm laser pulses (7 ns, 10 Hz). The nonlinear absorption coefficient β, nonlinear refractive index n2, and third order nonlinear susceptibility χ3 were calculated. The results show that all samples exhibit reverse saturable absorption (RSA) because of increasing metallicity and/or partial reduction of GO during laser illumination. The nonlinearity response of the GO/m-SWCNT films increase as the m-SWCNTs percentage increases. The high non-linear optical parameters of the GO/m-SWCNTs films make them as superior candidates for near-infrared (NIR) laser protection applications.

We report on the structural, thermal, linear, and ultrafast third-order nonlinear optical (NLO) properties of two novel anthracene chalcones: (2E)-1-(anthracen-9-yl)-3-(5-methylthiophen-2-yl)prop-2-en-1-one (5ML2SANC) and (2E)-1-(9-anthryl)-3-(2,4,5-trimethoxyphenyl)prop-2-en-1-one (245TMANC). The chalcones were synthesized by Claisen-Schmidt condensation reaction, and the single crystals were grown by the solvent evaporation method. The molecular structure was confirmed by FTIR and NMR spectroscopy, while the crystal structure was determined using the single crystal XRD. Both crystals belong to centrosymmetric monoclinic crystal system with space group P2 1 /n. The Hirshfeld surface was analyzed to understand intermolecular interactions, and the band structures - including HOMO-LUMO levels, excited state energies, GCRDs and MEPs-were studied using DFT. The ultrafast third-order NLO properties were investigated by Z-scan and degenerate four-wave mixing (DFWM) techniques using Ti: Sapphire amplifier laser delivering ∼50 fs pulses at 800 nm (1 kHz, ∼4 mJ, 2 W). Two-photon absorption, positive nonlinear refraction, optical limiting and optical switching behaviors were observed by Z-scan measurements. The time-resolved DFWM show that the decay time of 5ML2SANC is ∼127 fs, while for 245TMANC it is ∼142 fs. The second hyperpolarizability (γ) measured by Z-scan, DFWM and the estimations from the DFT theory are found to be in good agreement (∼10 -34  esu). The ultrafast optical response, significant NLO properties and thermal stability of the synthesized chalcones demonstrate their potential suitability in optical limiting and switching applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The nonlinear optical properties of push-pull chromophores, namely (E)-7-(4-bromophenyl)-2,5-bis(4-nitrophenyl)-3,4,5,6-tetrahydro-2H-1,2-diazepin-4-ol (A-π-D-π-A) and (E)-7-(4-bromophenyl)-5-(4-nitrophenyl)-2-phenyl-3,4,5,6-tetrahydro-2H-1,2-diazepin-4-ol (A-π-D-π-D), have been investigated using the z-scan technique. NMR, FT-IR, and UV-visible spectral analysis have been performed. The results were compared with density functional theory calculations employing the B3LYP/6-311++G (d, p) basis set. Geometry optimization, frontier molecular analysis, and TD-DFT calculations were conducted in various solvent environments to elucidate solute-solvent interactions. Gaussian 09 software was employed for natural bond orbital analysis, natural population analysis, and molecular electrostatic potential exploration. This comprehensive approach provides insights into the molecular structure and electronic properties of the investigated chromophores, shedding light on their potential applications in nonlinear optics. Normal coordinate analysis using the MOLVIB software has been used to assign the vibrational mode unambiguously. Theoretical second-order hyperpolarizability was computed, and NLO investigations have been employed to determine the second-order hyperpolarizability in both the polar and non-polar solvents. Further, the optical limiting capability was also examined., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this research work, the linear and nonlinear optical properties of linear low-density polyethylene (LLDPE) composites with anatase phase of titanium dioxide nanoparticles in different weight percentages are investigated. Solvent casting method have been used to synthesize the thin film of LLDPE/anatase nanocomposites. Thin films are characterized via XRD technique and field emission scanning electron microscope (FESEM). Wrinkles formed on the surface of thin films by adding the titanium dioxide. Linear optical and electrical parameters such as linear absorption coefficient, extinction coefficient, refractive indices, optical conductivity, and dielectric constants at various wavelengths from 190 nm to 2700 nm are determined for different weight percentages of nanoparticles in polymer nanocomposites. Z-scan technique has been employed to explore the nonlinear optical properties using CW laser at 532 nm wavelength. The nonlinearity is examined at various irradiance of laser to study the effect of irradiance on nonlinear optical properties. Pure LLDPE has saturable absorption (SA) at low laser irradiance. As the laser irradiance increases, the nonlinearity behavior turns from SA to reverse saturable absorption (RSA). The results show the suitability of the thin films for the applications in optical devices that involve the use of optical limiting properties of materials.

In this work, we investigated the nonlinear response of norbixin (C24H28O4) in acetone. The third- and fifth-order optical nonlinearities were measured using the conventional Z-scan technique, with 357 fs laser pulses at 1040 nm and low-repetition rate (1 kHz). It is shown that, at intensities lower than 99 GW/cm2, the nonlinear refraction process was determined by the only third-order process. However, at higher intensities, the third- and fifth-order refractive nonlinearities coexist with opposite signs: n2 = (4.43 ± 0.44) × 10−16 cm2/W and n4 = (−4.65 ± 0.46) × 10−27 cm4/W2. On the other hand, the open-aperture Z-scan measurements show an effective three-photon absorption (3PA) with 9.19±0.92×10-23 cm4/W2. The physical mechanisms of the observed nonlinearity are also discussed.

Tuning the third-order nonlinear optical (NLO) properties of graphene (G) is of great significance in nonlinear optics. In this work, Cu2Se/reduced graphene oxide (RGO) composites with different Cu2Se contents were prepared via a solvothermal method. The structure and morphology indicated that the Cu2Se nanoparticles were uniformly dispersed on the surface of the graphene nanosheets. The NLO properties of the composites with different Cu2Se contents were investigated via the Z-scan technique with a picosecond-pulse laser at 532 nm. The results showed that the Cu2Se/RGO composites had the properties of reverse saturated absorption (RSA) and positive nonlinear refraction, and their NLO properties could be effectively regulated by controlling the Cu2Se contents. The third-order nonlinear susceptibility of the Cu2Se/RGO composite with a 1.5:1 mass ratio of Cu2Se to graphene oxide could reach 6.52 × 10−11 esu, which increased five-fold compared to G. The introduction of Cu2Se improved the NLO response of G, which might be attributed to the content effect of Cu2Se in the composites and the synergistic effects stemming from charge transfer between the Cu2Se and RGO This paper lays a foundation for the further study on the applications of the Cu2Se/RGO composite materials in NLO devices.

A metal-organic lithium hydrogen oxalate hydrate single crystal was developed using the solution growth method. The single-crystal XRD analysis confirmed the triclinic structure and space group P1 along with the lattice parameters a = 3.439 Å, b = 5.097 Å, c = 6.141 Å, α = 78.50°, β = 84.89°, and γ = 81.41° of the grown crystal. The average crystallite size and strain within the material were calculated and compared using Debye Scherrer and Williamson-Hall method. The existence of diverse functional groups in the LHOH crystal was verified with the help of the FTIR analysis. The Z-scan method was carried out to acquire information about the developed material's third-order nonlinear characteristics that showed the material's self-focusing effect. The dielectric behavior of the compound was studied for various temperatures and frequencies. The Vicker’s microhardness analysis was carried out to collect information about the hardness number, yield strength, elastic stiffness, brittle index and fracture toughness of the grown crystal. The hardness number decreased when the applied load was increased, which indicated the normal indentation effect of the material.

The linear optical and electroluminescence properties of small molecular organic material tris-(8-hydroxyquinoline) aluminum (Alq3) are known and extensively investigated by many studies. However, the studies on the nonlinear optical (NLO) properties of this material are still scarce. Herein, the third-order NLO (TONLO) properties of Alq3 chloroform solutions with different concentrations have been examined using the Z-scan technique. At different laser powers and different laser wavelengths, the Z-scan signals were recorded using a continuous-wave (CW) laser beam. The open-aperture (OA) and closed- aperture (CA) Z-scan signals revealed strong TONLO properties. Both nonlinear refractive index (n2) and nonlinear absorption coefficient (β) showed negative values, and their smallest values were in the fold of 10−8 cm2/W and 10−2 cm/W, respectively. The negative values of n2 and β suggest thermal nonlinearity and saturable absorption (SA), respectively. The TONLO susceptibility (χ(3)) was calculated and found to be in the order of 10−6 esu. Besides, they increased with increasing the concentrations of Alq3 and laser powers. Therefore, the results indicate that Alq3 could be one of the potential materials as a saturable absorber for starting a passive mode-locking operation.

Hematin anhydride (β-hematin), the synthetic analogue of the malaria pigment, "hemozoin", is a heme dimer produced by reciprocal covalent bonds among carboxylic acid groups on the protoporphyrin-IX ring and the iron atom present in the two adjacent heme molecules. Hemozoin is a disposal product formed from the digestion of hemoglobin present in the red blood cells infected with hematophagous malaria parasites. Besides, as the parasites invade red blood cells, hemozoin crystals are eventually released into the bloodstream, where they accumulate over time in tissues. Severe malaria infection leads to significant dysfunction in vital organs such as the liver, spleen, and brain in part due to the autoimmune response to the excessive accumulation of hemozoin in these tissues. Also, the amount of these crystals in the vasculature correlates with disease progression. Thus, hemozoin is a unique indicator of infection used as a malaria biomarker and hence, used as a target for the development of antimalarial drugs. Hence, exploring various properties of hemozoin is extremely useful in the direction of diagnosis and cure. The present study focuses on finding one of the unknown properties of β-hematin in physiological conditions by using the Z-scan technique, which is simple, sensitive, and economical. It is observed that hemozoin possesses one of the unique material properties, i.e., nonlinearity with a detection limit of ∼ 15 µM. The self-defocusing action causes β-hematin to exhibit negative refractive nonlinearity. The observed data is analyzed with a thermal lensing model. We strongly believe that our simple and reliable approach to probing the nonlinearity of β-hematin will provide fresh opportunities for malaria diagnostics & cure in the near future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this report, we have presented the theoretical and experimental investigation of 2-Methylimdazolium 4-Nitrobenzoic Acid (2MI4NB) - an organic crystal. The good quality 2MI4NB single crystal was grown by slow evaporation technique. Both single and powder X-ray diffraction (XRD) analysis confirmed that the grown crystal structure is Triclinic with the P1 space group. The vibrational modes present in the chemical were validated through Fourier transform infrared (FT-IR) spectrum investigations. Density functional theory (DFT), a quantum chemical approach, has emerged as a potential or an effective tool for studying molecular structure and NLO properties and is being used frequently in applications involving NLO systems. HOMO-LUMO analysis and reactivity parameters were calculated. Molecular Electrostatic Potential (MEP), Natural Bond Orbital (NBO) analysis and first order hyper polarizability were studied by B3LYP theoretical level with 6-311++G(d,p) basic set. In addition, the Mulliken Atomic Charge was calculated with the same basic set. The thermal properties of the 2MI4NB crystal was analysed by TG-DTA studies. It shows that the two endothermic peaks were observed. The optical absorption spectrum shows that there is no absorption in the region of 430-1200 nm. The Z-scan analysis gives the third order NLO properties like refractive index and third-order NLO susceptibility of 2MI4NB crystals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The exact knowledge of optical material parameters is crucial for laser systems design. Therefore, the work reported herein was dedicated to the determination of an important parameter that is typically not known or only known with insufficient precision: the Kerr coefficient determined by the third order non-linearity, also called the n2-parameter. The optical Kerr effect is responsible for the accumulated nonlinear phase (the B-integral) in high energy laser amplifiers, which often represents a serious limitation. Therefore, the knowledge of n2 is especially required for new types of laser materials. In this paper we report measurements carried out on the widely used optical material Ytterbium-doped Yttrium Aluminium Garnet (Yb:YAG) ceramics. Furthermore, the new Neodymium-doped Calcium Fluoride (Nd:CaF2) crystal was investigated. Specifically, three different approaches have been employed to determine experimentally the nonlinear refractive index of these materials. Thus classical Z-scan technique (at two different wavelengths), the degenerated four waves mixing and the time-resolved digital holography techniques, were compared. These different approaches have permitted the precise measurements of these parameters as well as their dispersion estimations.

This research work focuses on the synthesis and characterization of p-toluidinium 2,4-dichlorobenzoate (PTDA), organic non-linear optical crystal grown at room temperature. Single crystal X-ray diffraction (SCXRD) analysis was used to analyze the lattice parameters under the centrosymmetric space group of P121/c1 with a monoclinic crystal system. The crystalline nature and phase identification of the sample was analyzed by powder X-ray diffraction (PXRD) analysis. FT-IR and 1 H NMR were used to identify the functional groups and various vibrations present in the grown crystal. The cut-off wavelength was observed at 284 nm from the transmittance spectrum, and the optical bandgap value (4.06 eV) was also determined from UV-visible analysis. TG-DTA analysis was carried out to understand its thermal properties. The mechanical strength of the material plays an important role in fabricating devices. Open-aperture Z-scan analysis was taken in order to get its third-order nonlinearity using Nd: YAG nanopulsed laser. PTDA crystal exhibits reverse saturable absorption and shows two-photon absorption- induced optical limiting behavior. Theoretical calculations were done by using Gaussian 09 software with a basic set of B3LYP/6-311G++ (d, p) to provide optimized molecular geometry, Frontier Molecular Orbital (FMO), and NBO analysis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Non-linear optical (NLO) features of 3-[(4-Nitrophenyl Azo)]-9H-Carbazole-9-Ethanol (NPACE) chromophore were investigated by FT-IR, FT-Raman, and UV-visible spectra aided by Density Functional Theory (DFT) using the B3LYP/6-311++G(d,p) basis set of Gaussian 16 W package. It is observed from the DFT calculation that the slight increase in the endocyclic angle of C 13 -C 14 -C 15 and the reduction in exocyclic angle of N 40 -N 39 -C 14 and C 15 -C 14 -N 39 ascertained by experimental XRD values indicating the intramolecular charge-transfer interaction between the carbazole and nitrophenyl group through the diazo bridge. The vibrational contribution to the linear electro-optic effect is 15% of the total hyperpolarizability being calculated at B3LYP/6-311++G (d, p) for the NPACE molecule. It is also observed that the 8a, 19a, and 19b modes of the carbazole ring and the 8a, 8b, and 19b modes of the phenyl ring are found to be simultaneously and intensely active in IR and Raman spectra explaining the charge transfer interactions throughout the molecule. The low value of the HOMO- LUMO energy gap (2.5843 eV) and the deviation between the measured absorption wavelength (3.36 eV) from the computed (3.87 eV), both these facts substantiate the intramolecular charge transfer. The polarizability and first-order hyperpolarizability were calculated as 6.48 × 10 -24 and 3.8 × 10 -29 esu, respectively. The second harmonic generation (SHG) measurement experiment of NPACE was carried out using the powder method. The SHG efficiency is measured in comparison with the urea standard. The calculated torsional mode at 20 cm -1 is in excellent quantitative agreement with the experimentally determined terahertz absorption peak. The two-photon absorption coefficient of NPACE was estimated to be 0.9 × 10 -11 mW -1 , which is mainly due to the D-π-A type of molecular structure, and the optical limiting threshold for NPACE was estimated to be 1.52 × 10 13 Wm -2 enabling this material as a potential candidate for optical limiting applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Monitoring neural activity and associating neural dynamics with the anatomical connectome are required to understand how the brain works. Neural dynamics are measured by electrophysiology and optical imaging. Since the discovery of the two-photon excitation phenomenon, significant progress has been made in deep imaging for capturing neural activity from numerous neurons in vivo. The development of two-photon microscopy is aimed to image neural activity from a large and deep region with high spatial (x, y, and z) and temporal (t) resolutions at a high signal-to-noise ratio. Imaging deep regions along the optical axis (z-axis) is particularly challenging because heterogeneous biological tissues scatter and absorb light. Recent advances in the light focus modulation technology at high speeds in three dimensions (x, y, and z) have allowed multiplane two-photon imaging. z-Focus control by varifocal optical systems, such as ferroelectric liquid lenses, gradient refractive index lenses, and adaptive optical element systems, and multiplexing by time- and wavelength-division strategies have allowed to rapidly observe specimens at different focal depths. Herein, we overview the recent advances in multiplane functional imaging systems that enable four-dimensional (x, y, z, and t) analysis of neural dynamics, with a special emphasis on z-scanning mechanisms and multiplexing strategies., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Linear and nonlinear optical properties of near-infrared laser grade dye LDS 821 in different solvents and Salmon Deoxyribonucleic acid (DNA) were studied using spectroscopic and Z-scan techniques. UV-Vis absorption spectrum of the dye shows a bathochromic shift with a decrease in the solvent polarity parameter, and in DNA, the dye exhibits a hypochromic shift. The fluorescence spectrum of the dye does not show any notable correlation with the solvent polarity parameter, but in DNA, the fluorescence intensity of the dye decreases with the incremental addition of DNA. Molecular docking studies reveal that the dye intercalates on the major grooves of DNA. Nonlinear optical properties of the dye in different solvents and phosphate buffer solution with varying DNA concentrations were studied using the Z-scan technique using a Q-switched Nd: YAG laser operating at fundamental and second harmonics. A closed and open aperture Z-scan of dye in different solvents was carried out to estimate the nonlinear refractive index, excited-state absorption cross-section, and two-photon absorption coefficient (TPA). The variation in nonlinear optical properties of the dye in different solvents was due to solvent-induced structural modifications. Theoretical investigation on nonlinear optical properties of the dye in different solvents was carried out using density function theory. The theoretical first and second-order hyperpolarizability was calculated using B3LYP functional. The predicated nonlinear optical parameters of the dye in different solvents does not show any direct correlation with solvent polarity. Nonlinear absorption of the dye in phosphate buffer solution (PBS) and DNA were estimated. The nonlinear absorption of the dye in PBS decreases with the addition of DNA. Molecular docking studies were carried out to determine the structural changes induced in dye due to the intercalation with DNA., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Dopamine (DA) is a widely researched catecholamine best known for its role in motor, motivation, addiction, and reward. Disruption in dopamine homeostasis and signaling within the central nervous system (CNS) can lead to disorders such as attention deficit hyperactivity disorder (ADHD), schizophrenia, Parkinson's disease, and obsessive-compulsive disorder. In the periphery, circulating DA is stored in blood platelets, and its disruption correlates with pathological conditions such as head and neck paragangliomas, Huntington's chorea, and schizophrenia. Various methods to sensitively and selectively detect dopamine have been reported, but sparse attempts have been made to exploit its intrinsic properties. Previously, we have harnessed dopamine's natural mid-ultraviolet auto-fluorescence to carry out its label-free imaging in live brain tissues. Recently, we used the closed-aperture (CA) Z-scan method to provide the first line of evidence on the existence of dopamine nonlinearity. Here, we utilized this simple, sensitive, and straightforward CA Z-scan technique and coupled this with theoretical simulations to further investigate the nonlinear photophysical properties of DA under physiological conditions. Our combined approach revealed that the nonlinear property of dopamine is governed by the thermo-optical effects, and the CA Z-scan profiles can be modulated by parameters such as phase-shift, orders of absorption, and time dependency. Simple and physiologically relevant systems, such as the platelets, are amenable to Z-scan analysis, thereby empowering us to scrutinize in the future if nonlinearity and its alterations, if any, have a direct bearing on DA homeostasis and associated diseases., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Although traditional treatments are able to increase cancer survival rate, undesirable impact on off-target tissues are considered a limitation of these approaches. Nanotechnology-based treatments have been proposed as a possible option to enhance targeting., Further,current methods for evaluating cellular damage, are time consuming, highly dependent on the operator skills, and expensive. The aim of this study was to evaluate the capability of nonlinear optical response of cells to determine cellular damages during conventional and nano-technology based treatments., Methods: Three different cancer cell lines, CT26, KB, and MCF-7 were used in this study. The alginate hydrogel co-loaded with cisplatin and Au nanoparticle (ACA) nanocomplex and gold-coated iron oxide nanoparticle (Au@IONP) were considered for chemo- and chemo-photothermal therapies, and thermo-radiation therapy, respectively. The sign and value of nonlinear optical absorption coefficient and imaginary part of the third-order nonlinear susceptibility of cells were computed. MTT assay was utilized as a reference method., Results: The value of nonlinear optical indices increased with increasing cellular damage and cell death. The linear regression analysis indicated high correlation between nonlinear optical indices and MTT results, in all treatments., Conclusion: The nonlinear optical indices are robust from confounding factors, namely treatment approach (traditional and nano-technology based), treatment modality (chemotherapy, thermotherapy, photothermal therapy, and radiation therapy), and cell types. Nonlinear optical properties of cells can be used as a rapid estimation method for cell damage, at the nanoscale level., (Copyright © 2021. Published by Elsevier B.V.)

The present work reports the effects of meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS 4 ) aggregation on its excited states absorption spectra, triplet states quenching by molecular oxygen and singlet oxygen production. Experimental techniques such as optical absorption, Z-scan with a white light continuum source and the Laser Flash Photolysis were used to fulfil the study. J-aggregates possess reverse saturable absorption in the 505-660 nm spectral range with a peak centered close to 540 nm. These facts together with their fast relaxation time suggest that they can be employed as material for ultrafast optical limiting and switching. Even though aggregation reduces the porphyrin excited-state lifetimes and quantum yields, it does not reduce the probability of the contact between the quencher and the excited aggregate. Aggregation does not change the contribution of energy transfer mechanisms to triplet state quenching by molecular oxygen. The production of singlet oxygen, the intense absorption in the phototherapeutic window and the high efficiency of conversion of light energy into heat, allow consider J-aggregates as a theranostic agent for photomedicine. It is proposed to use J-aggregates for diagnostics by photoacoustic images and in combination with a near-infrared photodynamic/photothermal dual mode therapy, thus improving synergistically the therapeutic response., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Broadband hyperspectral z-scan using a supercontinuum light source is a convenient technique to obtain spectrally resolved nonlinear optical properties of the materials under investigation. Post-processing and segregation of the data obtained from the supercontinuum based hyperspectral z-scan measurement aids in determining the nonlinear optical properties with high spectral resolution. However, few data models exist to store and represent the large amount of information acquired from the hyperspectral z-scan measurement. In this paper, a 3D data model for representing the data obtained from broadband z-scan measurements and analysis is presented. This method would help in the quick characterization of spectrally resolved nonlinear optical properties of materials from a single z-scan measurement. The proposed model is used for obtaining the spectrally resolved nonlinear optical properties of rhodamine 6G., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The dye of azo compound is prepared by coupling reaction of dizonium salt of sulfanilamide with benzoylacetone. The product is characterized by FTIR spectroscopy, Mass spectroscopy and 1 H NMR spectroscopy. The geometries of the synthesized dye is optimized using B3LYP method and 6-31G (d,p) basis sets. Nonlinear optical properties are investigated theoretically by calculation of some quantum chemical descriptors using the DFT/B3LYP method with a 6-31G(d,p) basis set in comparison with urea as a standard. The UV-visible spectrum of synthesized azo dye are calculated using TD-DFT with B3LYP/6-31G(d,p) level. The nonlinear refractive index of the prepared dye is calculated via the diffraction ring patterns and Z-scan techniques using 473 nm visible, continuous wave laser light. The diffraction ring patterns are numerically simulated using the Fresnel-Kirchhoff theory with reasonable agreements. The property of optical limiting of the azo dye is tested., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The Z-scan and DFT techniques were explored to investigate the non-linear optical properties of anthraquinone fused imidazole-based D-π-A dyes. With the help of UV-visible spectral analysis, pH study, CV analysis, HOMO-LUMO interaction, MEP plots, and quinoidal character the influence of intramolecular charge transfer characteristics and H-bonding process on electronic and photophysical studies of anthraquinone derivatives were understood. The dyes 2-(4-(diethylamino)-2-hydroxyphenyl)-3H-anthra[1,2-d]imidazole-6,11-dione (AQ1) and 2-(2-hydroxynaphthalen-1-yl)-1H-anthra[1,2-d]imidazole-6,11-dione (AQ2) displayed a single emission with pronounced Stokes shift and thermal stability (upto 290 °C). The dye AQ1 exhibited strong charge transfer character which is explained by the ICT process leading to high nonlinear susceptibility χ (3) in AQ1 3.43 × 10 -13 e.s.u relative to the dye AQ2 which has only ESIPT core. But, the dye AQ2 6.27 J cm -2 showed better optical limiting value. The NLO properties of AQ1 and AQ2 were computed by DFT functionals based on Hartree Fork (HF) percentage exchange. The dye AQ1 exhibits noticeable NLO properties. The global hybrid functionals with HF composition beyond 50% (BHHLYP, M06-HF) and the long rang corrected functionals (CAM-B3LYP, ωB97, and ωB97X) demonstrated comparable NLO properties relative to B3LYP and PBE0. It was observed that the combined effect of ICT and the H-bonding cores enhance the NLO properties. The experimental findings (Z-scan) were successfully correlated with theoretical (DFT) results., Competing Interests: Declaration of competing interest All the authors are aware of this submission., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, we investigated the possibility of interactions between the solvent molecules with the Heme group in the human hemoglobin. The results of this study answer a key question: whether the interactions of the Heme unit with its surroundings are interdependent or independent of the protein units of human hemoglobin. Contributions of the intermolecular interactions were determined by exploiting the solvatochromism spectroscopic data by Kamlet-Taft (KAT) polarity functions. Solvent polarity effects on the nonlinear properties of the Heme's groups in the human hemoglobin (Hb) were investigated via the Z-scan method. The experimental results obtained with spectroscopic and nonlinear optical parameters (absorption coefficient and refractive index) show that the mechanism of solvation and the interactions of Heme are controlled by suitable configuration of the protein units of hemoglobin. In other words, interactions of the Heme with α- and β-globins are an effective factor in controlling the optical behavior of Heme., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In order to determine the level of cell damage in cancerous cells, current cytogenetic tests have limitations such as time consumption and high cost. The aim of this study was to demonstrate the ability of nonlinear refractive (NLR) index as a predictor of breast cell damage caused by magneto-plasmonic nanoparticle based thermo-radiotherapy treatments. MCF-7 breast cancer cells were subjected individually to the treatment of radiation, radio-frequency (RF) hyperthermia, and radiation + RF hyperthermia. These treatments were repeated in the presence of magneto-plasmonic nanoparticle (Au@IONP). The MTT and nonlinear optical assays were used to evaluate the damage induced by different treatment modalities. The results of MTT were correlated with Z-scan, as the magnitude of nonlinear refraction increased with higher intensity of induced cell damages. In this regard, the lowest cell viability (38 %,) and highest magnitude of NLR index (+28.12) were obtained from combination of radiation (at 4 Gy dose) and hyperthermia treatment in the presence of nanoparticles. The proposed optical index (NLR) indicated high capability and can be used as an auxiliary tool to monitor induced cell damage during different treatment strategies. This technique is fast, noninvasive, does not impose cost, and finally does not waste materials., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The development of new methods to assess biomarkers of cardiovascular disease is currently a subject of scientific research. This article broadens our view of nonlinear optical responses of oxidized low density lipoprotein (LDL) evaluated using the Z-scan peak-valley distance and proposes a cutoff point. We investigated the association of peak-valley distance and some cardiovascular risk factors related with sociodemographic, clinical and anthropometric profiles and plasma biomarkers such as lipid and glucose profile, apolipoprotein, lipoprotein subfractions and omega 3 fatty acids. Z-scan analysis was performed using isolated LDL after ultracentrifugation in human blood samples collected after fasting. Peak-valley distance is a parameter that decreases directly depending on the oxidizability of LDL. As peak-valley distance was associated with relevant biomarkers of cardiovascular risk, we tested cutoff points for categorization and the best results were obtained using percentile < 75 (Low z-scan ) and percentile ≥ 75 (High z-scan ). The regression logistic models tested after establishing the cutoff point for peak-valley distance showed that increased levels of plasma high-density lipoprotein cholesterol, apolipoprotein A-I, large high-density lipoprotein subfractions and docosahexaenoic acid are directly associated with High Z-scan . Conversely, high levels of small LDL were associated with decreased odds of presenting High Z-scan. In conclusion, the cutoff point for peak-valley distance was able to identify atherogenic characteristics of LDL and its relationship with some parameters of high-density lipoprotein functionality., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Five chalcone-based molecules denominated by C-3 ((E)-1-(4-methoxyphenyl)-3-phenylprop-2-en-1-one), C-4 ((E)-1,3-bis(4-methoxyphenyl)prop-2-en-1-one), C-5 ((E)-1-(benzo[d][1,3]dioxol-5-yl)-3-(4-methoxyphenyl)prop-2-en-1-one), C-6 ((E)-3-(naphthalen-1-yl)-1-phenylprop-2-en-1-one) and C-7 ((E)-1-(4-methoxyphenyl)-3-(naphthalen-1-yl)prop-2-en-1-one) were synthesized by Claisen-Schmidt reaction in solution of NaOH in water/ethanol 2:1. The aldehydes used were benzaldehyde, anisaldehyde, and β-naphthaldehyde, while the used ketones were acetophenone, p-methoxyacetophenone, and 3,4-methylenedioxyacetophenone. Z-scan and hyper-Rayleigh scattering techniques were used to study the nonlinear optical properties of these compounds in dichloromethane medium. By using Z-scan technique with femtosecond pulses, two-photon absorption cross-sections (σ TPA ) were determined, while the first molecular electronic hyperpolarizabilities (β HRS ) were evaluated by the hyper-Rayleigh scattering technique, with picosecond pulses. From the recorded two-photon absorption spectra, it was identified that compound C-7 presented the highest σ TPA , regarding the HOMO-LUMO transition, with a value of 40 GM, while C-6 achieved the lowest value for the same transition with 13 GM. Concerning the values of the first molecular hyperpolarizability, compound C-4 presented the highest value, 38 × 10 -30  cm 4 statvolt -1 , while C-3 presented the lowest β HRS value of about 16 × 10 -30  cm 4 statvolt -1 . Time-dependent density functional theory calculations were used to simulate the one- and two-photon absorption spectra, as well to predict the theoretical value of β HRS in dichloromethane and vacuum medium., (Copyright © 2019 Elsevier B.V. All rights reserved.)

l-histidine tetra fluroborate (L-HTFB) is a semi-organic NLO material. Ab-initio computations were performed at CAM-B3LYP/ 6-311++g(d,p) level of theory to arrive at the structures, energies, and vibrational wave numbers. The experimental FT-IR and FT-Raman spectra of L-HTFB have been recorded and analyzed. It is compared with the simulated spectra. The scaled wave numbers obtained are in good agreement with the experimental values. Hirshfeld surface analysis represented in the 2D fingerprint plot reveals the interaction within the compound. Optimized geometry reveals that the complexes l -histidine (L-H) and tetrafluoroborate (TFB) are linked by H-F bond which provides inter and intra molecular hydrogen bonded interactions such as N 10 -H 16 ⋯F 25 , N 11 -H 17 ⋯F 22 , N 11 -H 14 ⋯F 24 , N 11 -H 14 ⋯N 10 and N 11 -H 15 ⋯O 12 . The inter-molecular distances H 17 ⋯F 22 , H 14 ⋯F 24 and H 16 ⋯F 25 are in between 1.82 Å and 2.53 Å. The intra molecular distances H 14 ⋯N 10 and H 15 ⋯O 12 are found to be at 2.17 Å and 1.71 Å which stabilizes lone pair electron of N 10 and O 12 with energies 11.89 and 59.91 KJ/mol respectively. The intra and inter molecular hyperconjugations responsible for the stability of the molecule are well identified theoretically using the NBO analysis. Third order optical nonlinearity is measured by means of the open aperture Z-scan technique which reveals that the crystal has optical limiting property. Photoluminescence results clearly indicate the use of L-HTFB as a new violet-light emitting material., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Organic compounds and vegetable origin oils are subject to scratiny in the photonics and nonlinear optics area, due to their high non-linear response: a characteristic linked to the molecular nature of these compounds and their own chemical bond. In the food industry, quick and non-invasive studies are needed to evaluate the nutritional quality of edible products. The nonlinear optical response of 4 vegetable oils was analyzed: extra virgin olive oil (EVOO), extra virgin sesame oil (EVSO), extra refined linseed oil (ERLO) and virgin avocado oil (VAVO), using the Z-scan technique. Where the third order electric susceptibility value (χ 3 ), refractive index (η 2 ) and characteristic non-linear absorption coefficient (β) were determined for each compound. Parameters that were found by measuring the transmittance as a function of the excitation power using a Nd: YAG laser of 532 nm operating in CW mode. In addition, the η 2 response was compared according to the oil type, it was determined that EVOO presents a greater non-linear response at low excitation potencies. Therefore, an additional study was performed on samples exposed to thermal stress to evaluate oxidative stability, again using the Z-scan technique n order to review the relationship between nonlinear optical properties with chemical changes resulting from heating., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Serotonin (5-hydroxytryptamine, 5-HT) is a crucial endogenous monoamine neurotransmitter that modulates neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. There have been numerous attempts to study the biochemical and photophysical properties of serotonin to carry out its molecular imaging and quantitative estimation. Here, we investigate the properties of serotonin at physiological concentration and pH using a continuous wave (CW) laser excitation closed-aperture (CA) Z-scan technique. Serotonin is packaged at high concentration inside the acidic environment of vesicles, and upon release gets diluted at the release sites in a neutral pH environment. Our solution-based measurements indicate that serotonin showed negative refractive nonlinearity and positive absorptive nonlinearity at a neutral pH. However, in the acidic medium, it showed negative refractive nonlinearity and mostly negative absorptive nonlinearity. The effect of excitation laser power on the observed nonlinearity is also verified. We attribute the origin of the nonlinearity in serotonin to the thermal lensing effect. Our robust and straightforward strategy to probe the monoamine neurotransmitter properties will provide new avenues to investigate serotonergic processes., (Copyright © 2018. Published by Elsevier B.V.)

Current methods for determining the cellular effects of a treatment modality need expensive materials and much time to provide a researcher with results. The aim of this study was to evaluate the potential of nonlinear optical characteristics of cancer cells using Z-scan technique to monitor the level of cellular uptake and cell damage caused by a nanotechnology based treatment modality. Two nanocomplexes were synthesized and characterized. The first one was made of alginate hydrogel co-loaded with cisplatin and gold nanoparticles (AuNPs) named as ACA nanocomplex. The second one, named as AA nanocomplex, was the same as ACA, but without cisplatin and this AA nanocomplex was considered as the control for ACA. Different groups of CT26 mouse colon cancer cell line received various treatments of cisplatin, ACA, and AA nanocomplexes and then the samples were prepared for Z-scan studies. The MTT assay was used to evaluate the cytotoxicity induced by different treatment modalities. Transmission electron microscopy (TEM) and inductively coupled plasma-mass spectrometry (ICP-MS) were used for qualitative and quantitative assessments of the level of AuNPs cellular uptake. The trend of nonlinear optical properties changes for treated cells was in agreement with MTT, TEM and ICP-MS results. Z-scan technique was able to successfully indicate the occurrence of cell damage. It was also capable to determine the intensity of cell damage induced by ACA nanocomplex in comparison to free cisplatin. Furthermore, Z-scan results showed that it was able to discriminate the differences of optical properties of the cells incubated with ACA nanocomplex for various incubation times. Nonlinear optical characteristics of a cell may be considered as a reliable indicator to predict the level of cellular effects induced by a nanotechnology based treatment modality. The protocol suggested in this article does not waste materials, not take much time to provide the results, and it is inexpensive technique., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Cancer is a disease that effects cell metabolism causing an imbalance in the health of the patient. On the other hand, malnutrition, presented by oncological patients, is caused by both the disease and its treatment. Some serum biochemical parameters cannot be determined by the traditional method of laboratory blood analysis (spectrophotometry). Among the various techniques that could be used for blood biochemical analysis, we opted for the Z-scan technique, due to its sensitivity to the reading of blood components. Our objective in this work was to compare the data obtained by the Z-scan technique and the spectrophotometry of the serological samples of children with solid tumors and leukemia under treatment, receiving or not selenium supplementation in a randomized, double-blind clinical trial. The biochemical parameters were read based on blood. These blood sampling made at different stages of chemotherapy and selenium supplementation. At each of these stages, the cholesterol, glucose and triglycerides parameters were read using the Z-scan and spectrophotometry techniques. We observed that selenium helps in balancing the health of these patients, and corroborates with our hypothesis that the Z-scan technique may be an alternative for the determination of biochemical parameters., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Patients with BC have a higher amount of cell-free circulating DNA (CFCDNA) in the blood and urine than healthy people. We aimed to verify if the Z-Scan method could analyze the concentrations of uDNA (urinary) and pDNA (plasma) in relation to the time of collection during treatment for patients with bladder cancer., Methods: Peripheral blood and urine samples were obtained from 30 patients with BC at the time of diagnosis, 45, 90 and 180 days after initiating treatment; 5 μL of k-DNA (k = u or p) was added in 250 μL a solution of 1:1000 Ethidium Bromide dye (EtBr) in water. Continum laser Nd:YVO4, wavelength λ = 532 nm was used. Samples of uDNA and pDNA in water were submitted to the laser with an incident power of 84.5 mW and an exposure time of 30 ms., Results: There was a different concentration of pDNA and uDNA during the treatment of patients using both optical techniques. However, the reaction rate of pDNA and uDNA was similar with spectrophotometry, whereas the z-scan technique presented different values., Conclusion: Z-scan technique has potential for use in the differentiation of pDNA and uDNA concentrations, which are distinct in patients with BC and healthy people., (Copyright © 2019 Elsevier B.V. All rights reserved.)

BOPHY (BPY) and BODIPY (BDY) dye bearing benzyl group (Bn) at 4,4' and 2,6 position respectively were synthesized and characterized. The fluorescence decay measurements were performed which reveal that benzyl BOPHY (Bn-BPY) has shorter fluorescence lifetime compared to benzyl BODIPY (Bn-BDY). The difference in transition dipole moment is found to be 6.93 and 11.3 D for Bn-BDY and Bn-BPY respectively in toluene. The molecular electrostatic potential (MEP) plot shows Bn-BDY is more polarised compared to Bn-BPY. The nonlinear optical (NLO) property was evaluated using Z-scan measurement. The molecular electronic arrangement of Bn-BPY significantly affects the nonlinear absorption properties resulting into reverse saturable absorption (nonlinear absorption coefficient β = 0.256 × 10 -11  m/W). In contrast, the Bn-BDY displays saturable absorption character. The calculated third-order nonlinear susceptibility χ (3) value is 12.23 × 10 -13  esu and 2.49 × 10 -13  esu for Bn-BDY and Bn-BPY respectively. The power limiting behaviour of Bn-BPY displays limiting threshold energy around 70 Jcm -2 with clamped output at ~35 Jcm -2 ., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Hybrid meso BODIPY dyes are synthesized and their linear and non-linear optical properties are studied. Time-resolved fluorescence lifetime decay is found to be identical for all dyes irrespective of meso substituents. The Z-scan experiment performed to calculate the nonlinear absorption coefficient (β) and third-order nonlinear susceptibility (χ 3 ). Global hybrid (B3LYP and BHHLYP) and range-separated hybrid (CAM-B3LYP) functional with the basis set 6-311++G(d,p) was employed to determine the theoretical linear and non-linear optical properties. The computed β 0 value of all the three dyes was found to be superior to that of urea (βo = 0.371 × 10 -30  esu). Introduction of meso substituent directly affects the polarizability and second-order hyperpolarizability of the dyes. Thermal and reorientational effect of the investigated NLOphoric dyes were studied., (Copyright © 2018 Elsevier B.V. All rights reserved.)