Third-order NLO Susceptibility Research Articles

Synthesis, crystal structure, spectroscopic and computational studies of NLO active 2-methylimdazolium 4-nitrobenzoic acid single crystal

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.

Investigations on structural, dielectric, and third-order nonlinear optical studies of Ni0.5Zn0.5Fe2O4 nanoparticles by microwave combustion method with different fuels (glycine, urea and citric acid)

In this article, Ni0.5Zn0.5Fe2O4 nanoparticles (NPs) were synthesized via microwave-assisted combustion method. XRD investigation indicates the cubic spinel structure. At ambient temperature, the dielectric constant and loss were determined by modulating the applied frequency (50 Hz to 200 kHz). The calculated third-order NLO susceptibility (χ(3)) was found for glycine (2.385 × 10-6esu), urea (0.9696 × 10-6esu) and citric acid (2.755 × 10-6esu). However, this work reveals that synthesized NPs have high convenience for optoelectronic, optical switching, and limiting applications.

Exploring linear and nonlinear optical behaviour of morpholine p-nitrophenol crystal: Computational and experimental analysis

Optically good quality morpholine p-nitrophenol (MPN) crystal was effectively grown from a slow evaporation technique. Unit cell parameters of MPN were estimated by single crystal X-ray diffraction and it crystallizes in the P21/c space group. The existence of several functional groups in MPN is established by FTIR analysis. UV–vis-NIR spectroscopy inspected the lower cut-off wavelength and band gap energy of MPN. A fluorescence spectral analysis of MPN was carried out. Experimental and computational calculations of nonlinear optical activity have been studied. The second harmonic generation of MPN is 1.9 times greater than the reference KDP material. Using the Z-scan approach, the grown crystal's third-order NLO susceptibility (χ3) was determined. The laser damage threshold of MPN crystal is studied and it is estimated as 5.12 GW/cm2. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and molecular tying-up explorations were executed. Ground state enhanced geometry and molecular electrostatic potential (MEP) were analysed.

Substantial effect of Cr doping on the third-order nonlinear optical properties of ZnO nanostructures

Here in, the present work we report the influence of Cr doping on the nonlinear properties of hydrothermally prepared ZnO nanoparticles. Structure has been confirmed from XRD analysis and exhibit a hexagonal wurtzite structure. Observed peak shift and decrease in crystallite size observed from XRD analysis confirms the successful Cr doping. FE-SEM images show distorted rod-like morphology and the doping percentages are confirmed from the EDAX spectra. The XPS spectrum confirms the existence of oxygen vacancies, which validates the existence of divalent oxidation states of zinc and the trivalent state of chromium. The calculated bandgap values validate thatZn0.98Cr0.02O nanoparticles exhibit the lowest bandgap energy due to the presence of optically active sub-levels within the bandgap region. Variation in peak intensity was observed from the Raman spectra, which validates the addition of Cr into lattice sites of ZnO. Under continuous wave (CW) laser regime, the Z-scan method was used to determine the third order nonlinearity and demonstrate, Zn0.96Cr0.04O nanoparticle show a combined effect of saturable absorption (SA) and reverse saturation absorption (RSA) under open aperture measurements with an increase in nonlinear absorption coefficient (βeff), and third-order NLO susceptibility (χ(3)) values on increasing Cr3+ doping concentration.

Growth, Structural, Spectral, Thermal, Optical, Second and Third Order Nonlinear Optical Properties of Imidazolium Hydrogen Squarate (IHS) Single Crystal

Abstract: Imidazolium hydrogen squarate (IHS) crystal has been grown by slow evaporation solution growth technique at room temperature. The lattice parameters of grown crystal were determined using single crystal X-ray diffraction data and compared with powder XRD. Single crystal XRD shows that the crystal crystallizes in monoclinic system with noncentrosymmetric space group Pc. The crystallinity of the grown crystal was confirmed by X-ray powder diffraction analysis. FT-IR and FT-RAMAN analyses qualitatively confirm the various functional groups present in the grown crystal. The 1H and 13C NMR spectra were recorded to establish the molecular structure. Thermal properties of title crystal were studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The UV-Vis-NIR transmission spectrum was recorded to find the band width of optical transmittance window and the lower cutoff wavelength. The optical band gap value of the material is evaluated to be 5.6 eV. The second harmonic generation efficiency was calculated by the Kurtz and Perry powder method using a Q-switched mode locked Nd: YAG laser emitting 1064 nm laser as source. Finally, Z-scan technique was employed to determine the nonlinear refractive index, nonlinear absorption coefficient and third-order NLO susceptibility to find suitability of the grown crystal in photonics and optoelectronics applications. Keywords: Single crystal; Powder XRD; thermal analysis; SHG; Z-scan studies

Concentration effects on optical properties, DFT, crystal characterization and α-glucosidase activity studies: Novel Zn(II) complex

A novel Zn(II) complex of 6-ClpicH and picH was synthesized and its structure was determined by XRD technique. The detailed experimental optical susceptibility and band gap, refractive index, linear polarizability, optical and electrical conductivity parameters in various concentrations were investigated by means of the UV–Vis spectroscopic data. The optical band gap, refractive index (n), linear optical susceptibility (χ(1)), third-order nonlinear optical susceptibility (χ(3)), second- and third-order nonlinear optical (β and γ) parameters were examined by using DFT/M06-L and ωB97XD/6–311++G(d,p) levels. The IC50 value of Zn(II) complex against α-glucosidase was also obtained at 0.44 mM. The experimental band gap of the Zn(II) complex at 13, 33, 44 and 94 µM concentrations in ethanol were found to be 4.38, 4.37, 4.35 and 4.28 eV, respectively. The third-order NLO susceptibility χ(3) parameter at 94 µM concentration corresponding to the photon energies of 4.6 and 5.7 eV in the UV–Vis region were observed at 206.6 × 10-13 and 294.3 × 10-13 esu, respectively. Besides, the theoretical χ(3) values were obtained at 50.58 × 10−13 and 20.37 × 10−13 esu by using M06-L level. These results indicate that Zn(II) complex could be an effective third-order NLO candidate material. In brief, the detailed theoretical and experimental structural, spectral and optical properties of the Zn(II) complex were presented comparatively.

Exploring Unusual Electrochemistry and Nlo Properties of Highly Electron-Deficient β-Functionalized Porphyrins

A series of β-tetracyanobutadiene(TCBD) appended porphyrins, M-TCBDP (M = 2H (2), Cu(II) (3), Ni(II) (4), Co(II) (5), Zn(II) (6)) were synthesized and characterized by various spectroscopic and electrochemical techniques. These porphyrins exhibit mutiredox process. Particularly, the unusual reduction potential in the range of -0.06 to -0.10 V is the consequence of TCBD group present at the β-position. The existence of enhanced polarization and intramolecular charge transfer in the absorption spectra are held responsible for nonlinear optical responses exhibited by the M-TCBD series as compared to the precursor (H2-PE2 (1)). Femtosecond Z-Scan experiments were performed to elucidate the third-order nonlinear optical properties and the temporal response of these porphyrin molecules are investigated using pump-probe spectroscopy to study the excited state transient absorption dynamics. Z-scan measurement reveals that Co-TCBD (5) exhibits better nonlinear optical response as compared to free base porphyrins. Two-photon absorption coefficient (β) and the imaginary part of third-order NLO susceptibility (χ(3) ) were procured from open aperture experiment whereas close aperture experiment delivers magnitude and sign of nonlinear optical refractive index (η2) and the real part of χ(3) . The excellent optical limiting threshold of synthesized porphyrins makes them adorable material for laser protection.

Crystal growth, optical, thermal, mechanical and third-order nonlinear optical properties of L-lysine hydrochloride-doped sulphamic acid single crystals for optical applications

L-lysine hydrochloride-doped sulphamic acid (SA) crystals have been grown by slow evaporation technique. X-ray diffraction experiments confirmed the orthorhombic structure of SA crystal. The doped crystals have high transmission than the pure SA crystal. TG and DTA studies exhibit the title crystals are thermal stability up to 212 °C (pure), 210 °C (1 mol%) and 207 °C (2 mol%). The enhancement of the hardness value in the doped crystal was confirmed by the hardness test. The etch pit density was measured using chemical etching study. The photosensitivity of the grown crystals is 0.10 (pure), 0.36 (1 mol%) and 0.72 (2 mol%). The laser damage threshold (LDT) analyses show that the L-lysine hydrochloride-doped SA crystals have more LDT value than the pure SA crystal. Third-order NLO susceptibility was found to be 5.004, 5.864 and 6.050 × 10–10 esu for pure and L-lysine hydrochloride-doped (1 and 2 mol %) SA crystals, respectively.

Crystal structure, linear and nonlinear optical properties of three thiophenyl chalcone derivatives: A combined experimental and computational study

Abstract Three thiophenyl chalcone derivatives, (E)-1-(5-bromo-2-thienyl)-3-(4-bromophenyl)prop-2-en-1-one (B5B2SC), (E)-1-(5-bromo-2-thienyl)-3-(3-chlorophenyl)prop-2-en-1-one (3C5B2SC), and (E)-1-(5-bromo-2-thienyl)-3-(2-methoxyphenyl)prop-2-en-1-one (2M5B2SC), were successfully synthesized and crystallized. The structures were confirmed by experimental and theoretical FTIR and 1H NMR spectra. The crystal structures were determined by single-crystal XRD method. The B5B2SC, 3C5B2SC and 2M5B2SC crystallize in the monoclinic space groups P 21/c (centrosymmetric), P 2 (non-centrosymmetric) and triclinic space group P 1 ‾ (centrosymmetric), respectively. All these structures adopt trans configuration with respect to C6═C7 double bond. The chalcones have high thermal stability, a wide transparency in the visible region and small optical band gaps. The 3C5B2SC exhibits powder second-harmonic generation (SHG) intensity of about 1.7 times higher than Urea. From continuous wave (CW) laser (532 nm) Z-scan experimental data analyses, the third-order NLO parameters such as nonlinear absorption coefficient (β = ~10−4 cm/W), nonlinear refractive index (n2= ~10−9 cm2/W), third-order NLO susceptibility (χ(3) = ~10−7 esu), molecular hyperpolarizability (γh = ~10−27 esu), ground state absorption cross section (σg = ~10−22 cm2) and excited state cross sections (σex= ~10−20 cm2) were determined. The chalcones also exhibited optical limiting and all optical switching behaviour for CW laser operating at 532 nm wavelengths. The electric dipole moment, polarizability, hyperpolarizabilty, HOMO-LUMO energy gap, global chemical reactivity descriptors (GCRD), molecular electrostatic potentials (MEP) and natural bond orbital (NBO) analysis were computed theoretically (DFT). The results indicate that these three chalcones with thiophene moiety are potential materials for optical device applications.

Influence of bismuth nitrate doping towards the characteristics of L-Alanine nonlinear optical crystals

In the present study, an amino acid derivatives, L-alanine (LA) and Bismuth nitrate-doped L-alanine (BNLA) crystals were grown by the slow evaporation technique. The crystal structure and quality of the grown crystal were examined by single-crystal X-ray diffraction (XRD) and powder XRD. The X-ray diffraction analysis of LA and BNLA crystals confirmed the orthorhombic crystal system without any internal structural grain boundaries. The optical properties of the LA and BNLA crystals have been determined using UV-Visible spectroscopy and Photoluminescence (PL). The second harmonic generation (SHG) efficiency of the crystal was measured using Kurtz powder technique. The dielectric constant measurement was performed at room temperature for different frequencies. Photoconductivity tests show that the LA and BNLA crystals have negative photoconductivity value. On testing of the retentivity or remanent magnetization, the BNLA crystal has increased values as compared to the pure LA crystals, in addition to the observation of changes in coercivity. Further, the observation of maximum intensity peak for the BNLA crystal at 346.9 nm pointed out that the crystal has blue fluorescence emission. The third-order nonlinear optical properties of the grown crystal were studied using Z-scan technique. The enhancement in nonlinear refractive index and third-order NLO susceptibility value shows that the grown BNLA crystals may be of good quality and less in defect than that of pure LA crystals.

Investigations on structural, optical, dielectric, electronic polarizability, Z-scan and antibacterial properties of Ni/Zn/Fe2O4 nanoparticles fabricated by microwave-assisted combustion method

In this article, Ni0.5Zn0.5Fe2O4 nanoparticles (NPs) were synthesized by differing concentrations of fuel (lean, stoichiometric, and rich) via microwave-assisted combustion route. The effect of fuel content was used to explore their chemical, electrical, and nonlinear optical properties along with their antibacterial activity of the as-prepared Ni/Zn/ferrite NPs were studied. The XRD assures the cubic crystal structure of prepared NPs with no secondary phase. It is also clear that as lattice parameters increases, the mean crystallite size decreases as a change in fuel ratio. The optical energy bandgap values are estimated as 2.88, 3.28, and 3.0 eV, respectively. From the luminescence spectra, the Ni/Zn ferrite NPs exhibits strong green emission and weak violet emission color. The fuel ratio has a significant influence on the electronic polarizability properties of synthesized NPs. Closed and open aperture Z-scan technique reveals that the Ni/Zn ferrites NPs have self-defocusing nature, and reverse saturable absorption. The calculated values are NLA coefficients (10-5 cmW−1), NLR index (10−9 cm2W−1), and third-order NLO susceptibility χ(3) values of fuel lean (1.408 × 10−5esu), stoichiometric (2.75 × 10−6esu), and rich (2.634 × 10−5esu). Several identified microorganisms such as gram + Ve (S. aureus, B. cereus), and gram -Ve (P. aeruginosa, V. cholerae, and E. coli) have been tested for antibacterial activity against Ni/Zn ferrite nanoparticles. The ZOI values are 27 (lean), 24 (stoichiometric), and 25 mm (rich) which suggest great antibacterial activity against Pseudomonas aeruginosa gram-negative bacterium. However, this study shows excellent feasibility of applying prepared ferrite nanoparticles for optoelectronic devices and pharmaceutical processing applications.

Synthesis and characterization of GO doped bio-resource based composites for NLO and multifaceted applications

The objective of the present work is to synthesize three different types of cardanol based benzoxazines such as cardanol-{1,4-bis(4-aminophenoxy)ethane}benzoxazine (CBAE2Bz), cardanol-{1,4-bis(4-aminophenoxy)butane} benzoxazine (CBAE4Bz) and cardanol-{1,4-bis(4-aminophenoxy)octane}benzoxazine (CBAE8Bz) by varying aliphatic ether link chain length through solventless method. The benzoxazines obtained with varying chain length were converted in to three different types of composites using paraphenylenediamine (PPDA) functionalized gaphene oxide (f-GO) as nano-reinforcement with varying weight percentage and were characterized by different analytical techniques. The molecular structure of the monomers was confirmed from Fourier transform infrared (FTIR) spectroscopy, 1HNMR, 13C NMR and MALDI mass. Data obtained from thermal studies infer that the prepared composites possess good thermal stability and enhanced values of Tg with respect to weight percent of functionalized graphene oxide content. However, the values of thermal stability, Tg, dielectric constant and dielectric loss were marginally decreased with respect to increase in length of the spacer aliphatic chain. The SEM and TEM studies confirm the homogeneous dispersion and single layer thickness of graphene sheet, respectively. The feasibility of usage of f-GO/PCAE2Bz composite in both gram positive bacteria (Bacillus subtilis, Staphylococcus aureus) and gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli) environments were checked and the results obtained were discussed. Further, third-order NLO properties of open and closed aperture Z–scan results conclude that GO doped bio-resource based composites exhibit saturable absorption and self-defocusing type optical non-linearity. The third-order NLO susceptibility (χ3) of GO doped bio-resource based composites are increased with respect to quantity of reinforcement of GO to bio-based polymer. The maximum value of 1.03X 10−4 esu was observed and this nonlinearity is thermal in nature. Thus, the prepared composites may find wide range of applications in diverse surrounding conditions.

Fabrication and optical nonlinearities of composite films derived from the water-soluble Keplerate-type polyoxometalate and chloroform-soluble porphyrin.

Composite films derived from the water-soluble Keplerate-type polyoxometalate (NH4)42[Mo132O372(CH3COO)30(H2O)72]·ca. 300H2O·ca. 10CH3COONH4 (denoted (NH4)42{Mo132}) and chloroform-soluble tetraphenylporphyrin perchlorate [H2TPP](ClO4)2 are successfully fabricated by a layer-by-layer self-assembly method and characterized by UV-vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The structure of the {Mo132} and [H2TPP](2+) in the films remain intact in light of the results of UV-vis spectroscopy and XPS. UV-vis spectra measurements reveal that the amounts of deposition of {Mo132} and [H2TPP](2+) remain constant in every adsorption cycle in the composite films assembly process. Nonlinear optical properties of the composite films have been investigated by using the Z-scan technique at a wavelength of 532 nm and pulse width of 7 ns. The results show that the composite films have notable nonlinear saturated absorption and self-defocusing effects. The combination of {Mo132} with [H2TPP](2+) can result in composite films with remarkably enhanced optical nonlinearities. The interfacial charge transfer induced by laser from porphyrin to POM in the films is thought to play a key role in the enhancement of NLO response. The third-order NLO susceptibility χ((3)) of the composite films increases with the increase of film thickness.

Graphene nanoribbons generate a strong third-order nonlinear optical response upon intercalating hexagonal boron nitride

An artificial hybrid structure (named as BCNNRs) was designed by inserting wide-gap hexagonal boron nitride (h-BN) nanoribbon in between zero-gap graphene nanoribbon. Third-order nonlinear optical properties of this hybrid structure were calculated by employing the time-dependent density functional theory combined with sum-over-states method. Our calculations reveal that, distinct from individual BN nanoribbons or graphene nanoribbons, the hybrid BCNNRs exhibit a much stronger third-order nonlinear optical response. A giant third-order NLO susceptibility χ(3) of 1 × 10−4 esu is predicted, almost three orders of magnitude larger than that recently experimentally measured for graphene. Furthermore, a maximum third-order non-linear optical response of BCNNRs is obtained by adjusting the size of h-BN nanoribbons. The strong third-order non-linear optical response predicted for BCNNRs originates from the charge redistribution in graphene nanoribbon as h-BN ribbon is inserted. The results reported in this work show that insertion of a wide-gap semiconductor h-BN nanoribbon in zero-gap graphene can give rise to a strong three-order nonlinear optical response, which may guide the future development of structural design and exploration of more advanced nonlinear optical materials.

A method for determination of real and imaginary parts of third-order NLO susceptibility in solid solutions

A technique for the experimental determination of the modulus and the phase of third-order nonlinear optical susceptibility for a molecule solubilized in an isotropic matrix is proposed. The technique requires experimental determination of the concentration dependence of NLO susceptibility. Few examples of the theoretical predictions of the concentration dependence of solution susceptibility are computed and presented. The technique is applied for a deoxyribonucleic acid (DNA)–surfactant complex, doped at different concentration with Rhodamine 610 luminophore. The method allows, from the concentration variation of measured NLO susceptibility, to determine that of matrix and solute molecule as well as its phase.

Simultaneous two and three photon resonant enhancement of third-order NLO susceptibility in an azo-dye functionalized polymer film

We report the observation of simultaneous two and three photon resonances, enhancing the third-order NLO susceptibility in a thin film of an azo-dye polymer. The possibility of 2-3 orders of magnitude increase in χ((3)) susceptibility is sustained by quantum mechanical calculations. This improves the applications of azo-polymers in all optical signal processing as well as in nonlinear optical imaging.

Fabrication and optical nonlinearities of ultrathin composite films incorporating a Keplerate type polyoxometalate

Functional ultrathin films ({Mo132}/PEI)n have been fabricated by using the Keplerate-type polyoxometalate (NH4)42[Mo132O372(CH3COO)30(H2O)72].ca.300H20.ca.10CH3COONH4 (denoted by {Mo132}) and polyethyleneimine (PEI) through the electrostatic layer-by-layer self-assembly method. The structure of the {Mo132} in the multilayers is kept intact; the deposition amounts of PEI and {Mo132} remain constant in every adsorption cycle in the ultrathin multilayers assembly process. Nonlinear optical properties of the ultrathin films and aqueous solution of {Mo132} have been investigated by using the Z-scan technique at a wavelength of 532nm and pulse width of 5ns. The results show that both the aqueous solution of {Mo132} and the resulting ultrathin multilayer films have nonlinear self-defocusing effects, while the ultrathin films also have notable nonlinear saturable absorption. The third-order NLO susceptibility χ(3) increases with the increase of film thickness. The ultrathin films of ({Mo132}/PEI)n (n=28) have the nonlinear refractive index coefficient n2=−3.37×10−10esu, nonlinear absorption coefficient β=−5.09×10−6esu and the third-order NLO susceptibility χ(3)=3.8×10−11esu.

Synthesis and characterization of side-chain maleimide-styrene copolymers with new pendant azobenzene moieties

Four side-chain maleimide-styrene polymers have been synthesized from maleimide-alt-styrene copolymer (MASt) and some original azo-moieties using polymer analogous reactions. The structures have been obtained with good yields; remarkably, they showed a high chromophore load, up to ~100%. The polymers were characterized by means of SEC, FT-IR, 1H-NMR, DSC-TGA, and elemental analysis. The side-chain polymers exhibited improved solubility and enhanced thermal stability up to 320oC, while their glass transition temperatures have been found to be as high as 210oC. The third-order NLO refraction (n2) and susceptibility χ(3) coefficients were measured by Z-scan technique. The results of Z-scan measurements showed that the polymers have only nonlinear refraction, the nonlinear absorption being negligible.

A soluble coordination polymer and its sol–gel-derived amorphous films: synthesis and third-order nonlinear optical properties

A new soluble tris(8-hydroxyquinoline) aluminium (AlQ3)-based coordination polymer named CP-B8QBA-Al has been synthesized. In contrast with the traditional coordination polymers, this new coordination polymer CP-B8QBA-Al does not crystallize and can be fabricated into amorphous films by conventional spin-coating. The third-order nonlinear optical properties of the CP-B8QBA-Al films were investigated using the Z-scan method at 800 nm and 1064 nm, the results show the coordination polymer films have a third-order NLO susceptibility χ(3) value as high as 1.66 × 10−10 esu without nonlinear absorption.

Preparation and nonlinear optical properties of ultrathin composite films containing both a polyoxometalate anion and a binuclear phthalocyanine

An ultrathin composite film containing both polyoxometalate anion [PMo12O40]3− (PMo12) and a planar binuclear phthalocyanine, bi-CoPc, has been prepared by the electrostatic layer-by-layer self-assembly method. UV-vis measurements revealed regular film growth with each four-layer {PMo12/bi-CoPc/PSS/PAH} adsorption. The film structure was characterized by small-angle X-ray reflectivity measurements, X-ray photoelectron spectra, and AFM images. The nanothick film shows a third-order nonlinear optical response of χ(3) = 4.21 × 10−12 esu. Experimental investigations also indicate that the combination of polyoxometalate anions [PMo12O40]3− with the phthalocyanine bi-CoPc in multilayer films can enhance the third-order NLO susceptibility and modify the third-order NLO absorption of bi-CoPc.