Laser Induced Surface Damage Threshold Research Articles

Development and Evaluation of an Efficient Second Order Non-Linear Optical Single Crystal – 2-(3-Aminopyridinium-1-yl)-3-Carboxy-Proponate Monohydrate

A slow evaporation solution approach was used to create high-quality single crystals of 2-(3-aminopyridinium-1-yl)-3-carboxyproponate monohydrate (3ACPM). The single crystal X-ray diffraction was used to determine the crystal system and lattice characteristics. Software called Krystal Shaper was used to mimic the morphology of the 3ACPM. To evaluate the optical transmittance, UV-vis spectral analysis was used. The Nd:YAG laser was used to assess the laser-induced surface damage threshold (LISDT) of 3ACPM single crystal. The presence of second harmonic generation (SHG) was evaluated using the Kurtz-Perry powder method. Full Text: PDF References Y. Zhang, H. Li, B. Xi, Y. Che,vJ. Zheng, "Growth and characterization of l-histidine nitrate single crystal, a promising semiorganic NLO material", Mater. Chem. Phys. 108, 192 (2008), CrossRef S. Draguta, M.S. Fonari, A.E. Masunov, J. Zazueta, S. Sullivan, M.Y. Antipin, T.V. Timofeeva, "New acentric materials constructed from aminopyridines and 4-nitrophenol", Cryst. Eng. Comm. 15, 4700 (2013) CrossRef G. Peramaiyan, R. Mohan Kumar, "Nonlinear optical and laser damage threshold studies of an ammonium p-toluenesulfonate crystal", Appl. Phys. A 119, 707 (2015), CrossRef G.M. Corrales, D. Morales-Morales,S. Hernandez-Ortega, J.J. Campos-Gaxiolaa, A. Cruz Enrıquez, "2-(3-Aminopyridinium-1-yl)-3-carboxypropanoate monohydrate", Acta Cryst. E68, o853 (2012), CrossRef S.K. Kurtz, T.T. Perry, "A Powder Technique for the Evaluation of Nonlinear Optical Materials", J. Appl. Phys. 39, 3798 (1968), CrossRef S. Panchapakesan, K. Subramani, B.Srinivasan, "Growth, characterization and quantum chemical studies of an organic single crystal: 3-Aminopyridine 4-Nitrophenol for opto-electronic applications", J. Mater. Sci: Mater. Electron. 28, 5754 (2017), CrossRef

Growth, Structural, Spectroscopic and Thermal Analyses of Novel Organic Brucinum-3, 5 –Dihydroxybenzoate Dihydrate Single Crystals for NLO Applications

Along the line of available efficient nonlinear optical (NLO) organic single crystals in the literature, it is worthwhile to bring in a novel organic single crystal of Brucinium-3,5-dihydroxybenzoate dihydrate (B35D) which was successfully grown utilizing the technique of slow evaporation of solution at ambient conditions. As the solubility of B35D was found to be the highest in water-ethanol 1:1 mixed solvent among the conventional solvents, crystallization of B35D was accomplished by making use of the solvent. The required confirmation of the crystal structure of the crystal and its lattice parameter could be achieved by the single-crystal X-ray diffraction analysis such that B35D was found to be crystallized in the monoclinic system with the non-centrosymmetric space group C2. The recording of UV-Vis-NIR transmittance spectrum of the crystal was undertaken between the range of 300 and 900 nm whereby the lower optical cutoff wavelength was identified to be 321 nm. The spectral study of photoluminescence was carried out in the range of 300-600 nm by which the band gap energy was calculated to be about 3.8 eV (at 373 nm) indicating that B35D has a violet fluorescence spectrum. The thermal stability and melting point of the title crystal have been investigated through Thermo gravimetric and differential thermal analysis (TG-DTA) such that the thermal stability of the crystal was found to be 95.6 °C. The Nd: YAG Q-switched laser was employed so as to obtain the laser-induced surface damage threshold of the specimen which was estimated to be 3.1 GW/cm2. The Vickers microhardness test was implemented in order to arrive at the mechanical strength of the crystal. The performed non-linear optical study could reveal that the second-order harmonic generation (SHG) efficiency of B35D crystal is 2.16 times higher than KDP. So that B35D crystals are among the class of NLO materials.

Growth, optical, mechanical, dielectric properties of UV-nonlinear optical single-crystal of [(NH4) (Cd(NCS)3)]·C12H24O6

Single-crystal of ammonium (18-crown-6-ether) cadmium (II) tri-thiocyanate [(NH4)[Cd(NCS)3]; (ACCTC) has been grown with dimension 8 × 4 × 4 mm3 was grown from aqueous solution via slow evaporation solvent technique. The S-XRD was utilized to determine the grown single-crystal structure, where the crystalline compound of ACCTC adopts to be orthorhombic crystal system with the space group of Cmc21, and the calculated cell parameters are a = 14.7568 Å, b = 15.4378 Å and c = 10.6383 Å, volume V = 2423.54 Å3. The optical lower cut-off wavelength of the title compound of ACCTC is UV–vis-NIR spectra examined 239 nm. Moreover, the laser-induced surface damage threshold (LISDT), Vickers micro-hardness, and dielectric properties have been examined by the grown title compound of ACCTC. Overall, the experimental results suggest that a single-crystal of ACCTC can be the best nonlinear optical material and possess superior power density (Pd) compared to the KDP single-crystal.

Studies on the growth, optical, thermal and physical properties of an efficient second order nonlinear optical organic crystal: 2-amino-5-chloropyridinium-trifluoroacetate for optoelectronic and photonic device applications

The novel organic single crystal 2-amino-5-chloropyridinium-trifluoroacetate (2A5CTFA) has been synthesized andgrown successfully using methanol as solvent by continuous slow evaporation technique. The X-ray diffraction resultsreveals that the crystal 2-amino-5-chloropyridinium-trifluoroacetate crystallizes into monoclinic crystal system with the noncentrosymmetricspace group Pc. The vibrational spectrum of the sample by FTIR and FT-RAMAN study confirms thecharacteristic functional groups of the 2A5CTFA crystal. The optical absorption spectrum shows 85% of transmittance inthe entire UV-Vis-NIR region with cut-off wavelength at 345 nm. The crystal has a thermal stability of 137° C without anymajor weight loss in the TG curve. The photoluminescence spectrum of the crystal has a prominent violet emission peakcentered at 388 nm. The dielectric behavior of the crystal measured with various frequencies at different temperaturesreveals the normal behavior for optical materials. The second order NLO effect from the crystal is confirmed by theemission of green signal from the crystal upon tested with the aid of Kurtz powder analysis using Nd:YAG laser. The laserinduced surface damage threshold value of the crystal is found to be 1.05 GW/cm2. Overall, the outlined properties of thegrown crystal makes it suitable for opto-electronic and nonlinear optical device applications.

Mid-wave infrared planar optical device via femtosecond laser ablation on a sulfur-based polymeric glass surface

Sulfur-based polymer materials are attractive for infrared (IR) applications, as they exhibit profoundly high IR transparency, low temperature processability, and higher refractive index relative to conventional organic polymers. In this paper, the laser induced surface damage threshold of such sulfur-based polymeric glass is experimentally studied with femtosecond laser pulse exposure. The single- and multi-shot laser damage thresholds are determined as 41.1 mJ/cm2 and 32.4 mJ/cm2, respectively, and line width of laser scanning is proved to be controllable by laser energy implantation dose. The results enrich the technical knowledge of such novel optical material, and predict its processability by laser surface inscription. While, the amplitude-type binary planar devices based on femtosecond laser ablation are fabricated, and their imaging abilities are performed both in visible light and mid-wave IR regions.

Investigation on the optical, spectral, electrical, mechanical, and laser damage threshold studies of bis (4-acetylanilinium) tetrachloridozincate (B4ATCZ) crystal

An efficient semi-organic nonlinear optical bis (4-acetylanilinium) tetrachloridozincate [(C8H10NO)2 ZnCl4] (B4ATCZ) single crystal was synthesized and successfully grown by the slow evaporation method. The single-crystal X-ray diffraction data confirm that B4ATCZ crystallized into an orthorhombic crystal system (Cmca). The UV–Vis–NIR transmittance spectrum was taken to assess the optical transmission, cut-off wavelength, and bandgap energy. The TG–DSC investigation ensures that the B4ATCZ is stable up to 235 °C. The mechanical behavior of the B4ATCZ compound was determined by Vickers Microhardness analysis. The surface laser-induced damage threshold value of the grown B4ATCZ crystal was endowed to be 19.78 GW/cm2 on testing with 1064 nm Nd: YAG laser radiation. The positive photoconductive properties and charge transport mechanism of B4ATCZ crystal were analyzed through photoconductivity and dielectric studies. The electron excitation and lifetime measurements of the molecules in the B4ATCZ crystal were studied by fluorescence spectral analysis. The HOMO–LUMO analysis evidently interprets the occurrence of N–H⋯O and N–H⋯Cl intermolecular hydrogen bonds influencing the charge transfer in the system. The electrostatic potential surface reveals the possible sites for hydrogen bonding electrophilic and nucleophilic interactions. Third-order nonlinear optical activity evaluated by the Z-scan measurements indicates the self-focusing and reverse saturable absorption in the crystal. The aforesaid results affirm that the metal-organic B4ATCZ is a potential material for optoelectronic and nonlinear optical device applications.

Spectroscopic characterization and structural insights of 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione using vibrational, optical, electronic spectra, reduced density gradient and quantum chemical calculations

The molecule 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione was investigated by experimental and theoretical spectroscopic methodologies. The structural and spectroscopic data of the molecule in the ground state were calculated by density functional method (B3LYP) with 6–311G(d,p) basis set. The vibrational frequencies were calculated and were compared with experimental FT-IR and FT-Raman spectral data. The stability and charge delocalization of the molecule were studied by Natural Bond Orbital (NBO) analysis. UV-Visible spectrum and effects of solvents have been discussed by time-dependent TD-DFT approach. The orbital contributions of the molecule were done by density of energy states (DOSs). The HOMO and LUMO energies were also determined. The softness and electrophilicity indices for selected atomic sites were determined. Based on electron density weak interactions of the studied molecule are identified with the aid of RDG analysis. The chemical reactivity sites have been revealed by fukui function and molecular electrostatic potential (MEP) analysis. The SHG efficiency was examined by the Kurtz and Perry powder reflection technique. The third-order nonlinear optical property of title compound was studied by laser induced surface damage threshold and Z-scan techniques.

High surface laser-induced damage threshold of SrB4O7 single crystals under 266-nm (DUV) laser irradiation.

Under 266-nm (deep ultraviolet, DUV) laser irradiation, an SrB4O7 (SBO) single crystal has been found to exhibit a surface laser-induced damage threshold (LIDT) of ∼ 16.4 J/cm2, which is higher than those of a synthetic silica glass (4.8 J/cm2) and a calcium fluoride (CaF2) crystal (11.4 J/cm2). By catalyst-referred etching (CARE), the LIDT of an SBO crystal can also be improved to around 24.1 J/cm2, which is 1.4 and 6.0 times higher compared to an unetched crystal and a silica glass, respectively. With high surface LIDTs, SBO single crystals can then be used as optical window materials for high-power DUV laser systems.

Laser-induced damage threshold of the nonlinear crystals BaGa4Se7 and BaGa2GeSe6 at 2091 nm in the nanosecond regime

The surface laser-induced damage threshold (LIDT) of B a G a 4 S e 7 and B a G a 2 G e S e 6 nonlinear crystals was studied at 2091 nm. Both yellow and dark yellow phases of B a G a 4 S e 7 were investigated. The Ho:YAG laser generating nanosecond pulses at 2 kHz, 5 kHz, and 10 kHz was used as a radiation source. The R-on-1 procedure was applied to determine the 0% probability damage threshold. The LIDT of the dark yellow phase of B a G a 4 S e 7 without cleavage planes is very close to the B a G a 2 G e S e 6 LIDT and exceeds by ca. 30% the LIDT of the yellow phase of B a G a 4 S e 7 at 2 and 5 kHz.

Synthesis, crystal structure and solid-state properties of 4-(3-nitrophenylamino)-4-methylpentan-2-one picrate (3NAP): An efficient cocrystal for χ(3) optics

An organic 4-(3-nitrophenylamino)-4-methylpentan-2-one picrate (3NAP) cocrystal was synthesized using slow solvent evaporation technique and its crystal structure is reported. The 3NAP compound crystallized in monoclinic crystal system with centrosymmetric space group P21/c and the cell parameters are found to be a=8.6339 Å, b=19.1965 Å, c=13.2058 Å, α=90∘, β=106.725∘, γ=90∘ and V=2096.1 Å3. Best agreement between theoretical and experimental value of CHN elemental composition confirmed inclusionless compound formation. The reasonable FWHM value of prominent peak observed from high-resolution X-ray diffraction experiment indicates superior crystallinity of 3NAP. The load-dependent hardness values measured at (010), (010), and (001) – planes of 3NAP single crystal admit its mechanical anisotropy. Further, the work hardening coefficient confirms that the title crystal belongs to the soft material category. The dark and photocurrent of the 3NAP crystal were measured, and it exhibits positive photoconductivity. The laser-induced surface damage threshold of the 3NAP crystal was found to be 7.5 GWcm−2. Nonlinear coupling between the intermolecular charge transfer and an applied optical field enhanced third order nonlinear optical properties. The intermolecular charge transfer and interactions are proved to be true in 3NAP via Hirshfeld surface analysis. The third order nonlinear optical susceptibility (χ(3)) and optical limiting threshold under continuous-wave laser excitation was measured to be 3.96 × 10−6 esu and 3.44 × 103 Wcm−2. The superior physicochemical and nonlinear optical properties promote the title material as a promising candidate for nonlinear optical device applications.

Self-focusing behaviour of dichlorobis(sarcosinato)zinc(II) complex investigated by DFT computations, fluorescence, laser damaged threshold and Z-scan technique

Single crystals of the metal complex [ZnCl2(CH3NH2+CH2COO–)2] were grown by slow evaporation method and its structure was confirmed by SC-XRD method. The structural geometry, vibrational wavenumbers, UV–Visible spectrum and NLO properties were computed using DFT. The calculated frontier molecular orbital energy shows the charge transfer interactions that occur within the molecule which proves its reactivity and stability. Third-order nonlinear optical properties along with optical limiting behaviour were explored using Z-scan technique with 5 ns Nd:YAG laser pulses at 532 nm. The laser induced surface damage threshold was also studied, which recommends the complex as a promising material for laser-assisted applications.

NaSr3Be3B3O9F4 crystal growth and fourth harmonic generation at 266 nm

A high quality NaSr3Be3B3O9F4 (NSBBF) crystal with dimensions of 30 × 25 × 20 mm3 was grown from a modified NaF-LiF-B2O3 flux system using a seed oriented normal to the (1 0 1) plane. The effect of the temperature gradient on crystal growth is discussed. NSBBF possessed a large laser-induced surface damage threshold with a value of 7.9 GW/cm2. A maximum output power of 450 mW was obtained by the fourth harmonic generation of the Nd:YAG laser system with a pulse width of 10 ns, repetition of 10 kHz in a 5.0 mm thick NSBBF crystal.

Synthesis, crystal growth, and characterization of piperazinediium bis (4-aminobenzoate) dihydrate - An efficient third-order nonlinear optical single crystal for opto-electronic applications

Organic compound of protonated Piperazinediium bis (4-aminobenzoate) dihydrate C4H12N22+2(C7H6NO2−).2(H2O) (PZ4AB) was synthesized and crystal was grown by slow evaporation solution growth technique. Powder X-ray diffraction and High resolution X-ray diffraction studies affirmed the crystalline perfection of the grown crystal. Fourier transform infrared spectral analysis ascertained the frequencies of various functional groups present in PZ4AB crystal. Optical transmittance and optical band gap estimation explored the optical phenomena of PZ4AB crystal. The laser-induced surface damage threshold value of PZ4AB crystal was measured to be 1.0615 GW/cm2 for the 1064 nm Nd:YAG laser radiation. From Thermogravimetric and differential scanning calorimetric studies, the stability of PZ4AB crystal was ascertained. The dielectric manner was endowed as a function of frequency and temperature. The mechanically soft nature of the crystal was assessed by Vickers hardness measurement which exhibited the reverse indentation size effect. The nonlinear refractive index, absorption coefficient and the third-order nonlinear susceptibility of crystal were divulged by Z-scan technique.

Crystal growth, structure, mechanical, thermal, spectral and optical properties of organometalic of L – proline strontium bromide tetrahydrate single crystal for nonlinear optical applications

Growth of organometalic nonlinear optical (NLO) L – proline strontium bromide tetrahydrate (LPSBT) single crystals were reported for the first time by slow evaporation technique. Crystal structure was elucidated by single crystal X – ray diffraction analysis. Fourier transform infrared and FT – Raman spectroscopic studies were performed to identify the various functional groups present in the grown crystal. Optical transmittance of the grown crystal was investigated by UV–Vis–NIR spectral studies. The lower cut off wavelength of the grown crystal is observed at 240 nm. The photoluminescence spectral study of the grown crystal showed an emission peak at 410 nm. Mechanical strength was assessed by Vickers microhardness measurements. The dielectric constant and dielectric loss were studied as a function of frequency at various temperatures. Thermal stability of the grown crystals was studied by thermogravimetric analysis, differential thermal analysis and differential scanning calorimetry. The laser induced surface damage threshold for the grown crystal was determined using Nd:YAG laser. The Kurtz powder second harmonic generation efficiency of grown LPSBT is about 0.8 times that of potassium dihydrogen orthophosphate.

A methodical approach to physico-chemical analysis of bis (potassium hydrogen l-malate).malic acid – A semi-organic single crystal for nonlinear optical applications

Bis (potassium hydrogen l-malate).malic acid (PMM), a semi-organic nonlinear optical material was synthesized and crystals were grown from aqueous solution by slow evaporation solution growth technique (SEST). The lattice parameters and space group were confirmed by single crystal X-ray diffraction study. Powder X-ray diffraction study reveals the crystalline nature of the title material. Crystalline perfection of grown crystal was analyzed using high resolution X-ray diffraction rocking curve technique. Fourier transform infrared spectral analysis revealed the vibrational behaviour of chemical bonds of various functional groups. Surface feature of the grown crystal was analyzed through atomic force microscopy. Optical transmittance study shows that the grown crystal has good transparency in the entire visible region. The luminescent property of the title crystal was investigated through photoluminescence spectroscopy. Second harmonic generation efficiency was found using Kurtz-Perry powder technique. The laser-induced surface damage threshold value for the grown crystal as measured using a Nd:YAG laser. Thermal analyses reveal that the crystal is stable up to 230 °C. The mechanical strength of the crystal was assessed by Vickers microhardness tester. The dielectric behaviour and its parameters were established through dielectric study. Piezoelectric charge coefficient (d33) of the grown crystal was determined using piezoelectric analysis.

Growth, solvent effect, optical and electrical properties of sodium 4-hydroxybenzenesulfonate dihydrate

Abstract Single crystal of sodium 4-hydroxybenzenesulfonate dihydrate (Na-4-HBS) was grown from an aqueous solution by slow evaporation method. Powder X-ray diffraction study was carried out to identify the lattice parameters of the crystal. FT-IR spectral analysis confirmed the existence of various functional groups in the compound. The optical transmittance, cut-off wavelength and band gap energy were estimated from the UV-Vis studies. Photoluminescence studies revealed the transition mechanism by optical excitation. The variation of dielectric properties and AC conductivity of the grown crystal with frequency was studied at different temperatures. Measurements of mechanical properties of Na-4-HBS were carried out to find the hardness of the material. The laser induced surface damage threshold and relative second harmonic generation nonlinear optical properties of the grown crystal were studied using Q-switched Nd:YAG laser.

Spectroscopic investigation and non linear optical activity study on 7,7,8,8-tetra cyano quino dimethane

Abstract FT-IR and FT-Raman spectra of 7,7,8,8-tetracyanoquinodimethane(TCNQ) was recorded and analyzed. The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers of TCNQ and its related compounds have been performed using density functional theory(DFT) method with 6-311G(d,p) basis set. The detailed interpretation of the vibrational spectra has been carried out with the aid of Molvib program. The TD-DFT calculation has been compared with UV–Vis spectrum with different solvents. HOMO-LUMO energy gap, local softness and electrophlicity indices for selected atomic sites of the TCNQ and its related compounds were determined. The intermolecular interaction in the TCNQ were confirmed by using Hirshfeld surfaces. The NLO activity of molecule was confirmed by SHG analysis. The surface resistance and third-order nonlinear optical property of the crystal were studied by laser induced surface damage threshold and Z-scan techniques respectively using Nd:YAG laser with wavelength 532 nm.

Crystal growth, optical, physico-chemical and third-order nonlinear optical studies of morpholinium oxalate: a new organic single crystal for optical limiting application

A single crystal of morpholinium oxalate (MO) was grown by the technique of slow evaporation at ambient temperature utilizing water as a solvent. Single crystal XRD reveals the MO crystal belongs to the monoclinic system with a centrosymmetric space group of P21/n. Powder XRD study demonstrates the crystalline quality. HRXRD study illustrates the crystalline perfection of the crystal and it is the key necessity for device fabrication. The optical transmittance (55%), cut-off wavelength (λ = 330 nm) and band gap energy (Eg = 2.61 eV) were determined by optical studies. Laser-induced surface damage threshold (LDT) analysis appraises the aptness of grown crystal for device fabrications and also the surface roughness of the sample was determined. The thermal stability and decomposition of the crystal were studied by thermogravimetric (TG) analysis and it was found that the material was thermally stable up to 179 °C. The various thermodynamical parameters were determined from TG analysis. The dielectric constant ɛ’ and dielectric loss ɛ’’ divulges the electrical properties of MO crystal and the various electronic parameters were also calculated. The nonlinear optical (NLO) behavior and optical limiting property were analyzed from Z-scan technique. Microhardness measurement was executed to recognize the mechanical strength of the MO crystal and its hardness value is 1.65 kg/mm2.

飞秒脉冲激光对硅基多层膜损伤特性

In order to understand the ultrafast laser-induced damage mechanisms of typical imaging sensor's film structures, the damage characteristics of Si-based multi-layer films irradiated by a femtosecond pulsed laser were investigated, and the laser pulse fluence ranges and threshold conditions corresponding to various damage phenomena were evaluated. Si-based multi-layer films that were similar in structure of CCD were prepared by electron beam deposition. The damage characteristics of these films irradiated by a femtosecond pulsed laser with wavelength of 800 nm and pulse width of 100 fs under different pulse fluences and numbers were investigated using a metallurgical microscope. Experimental results showed that the laser-affected zone size increased linearly with pulse fluence in the range of 1.01 to 24.7 J/cm2. Surface damage caused by oxidation/amorphization, non-thermal ablation, and laser-induced plasma ablation could be observed in the laser irradiated zone, which tightly depended on the pulse fluence. Multi-layer damage could be observed and the damage probability increased from 1% to 51% in the pulse fluence range from 2.42 to 24.7 J/cm2. Irradiated by sequent pulses at a fluence of 1.01 J/cm2, the laser affected zone remained almost unchanged and the ablated depth increased with the pulse number. From the single pulse damage experiment data, the femtosecond pulse laser-induced surface damage threshold was evaluated to be 0.543 J/cm2 and laser-induced multi-layer stress damage threshold was linearly fitted to be 2.16 J/cm2. Sequent pulse irradiation with low fluence(≤ 1.01 J/cm2) also could lead to deep damage on the multi-layer film.

4-Dimethylamino pyridinium p-chlorophenolate a novel third order nonlinear optical single crystal: growth and characterization

4-Dimethylaminopyridinium p-chlorophenolate (4DMAPCP) organic crystals were grown by slow evaporation solution growth technique using ethanol as solvent at room temperature. Single crystal X-ray diffraction studies shows that the material crystallizes in monoclinic system with centrosymmetric space group P 21/c and the cell parameters are observed to be a = 9.68 A, b = 12.84 A, c = 11.60 A, Z = 4 and V = 1353 A3. FT-IR and FT-Raman spectral studies were performed for analysing and assigning the vibrations and also to identify the functional groups. The optical transparency window in the visible and near IR (470–1100 nm) regions was found to be good, thus fulfilling the requirement for nonlinear optical applications. The optical band gap of the material was found to be 3.73 eV. Thermogravimetric analysis and differential thermal analysis showed that the compound decomposes beyond 250 °C. Dielectric loss and dielectric constant measurements as a function of frequency and temperature were measured for the grown crystal. Vicker’s hardness test reveals that 4DMAPCP belongs to the soft category. The laser induced surface damage threshold for the grown crystal is much greater than that of KDP. Third order nonlinear optical parameters like refractive index (n2), absorption coefficient (β) and susceptibility (χ(3)) were assessed by Z-scan studies.