NLO Crystal Research Articles

Structural, optical, thermal and theoretical investigations on high efficiency NLO crystal: 4-Nitrobenzonitrile

Crystals of 4-Nitrobenzonitrile have been grown from the solution growth procedure. Various characterization techniques have been adopted like powder XRD, FT-IR, UV–vis, photoluminescence and Powder SHG to investigate the crystal further. Powder XRD data reveals that the title compound gets crystallize in to monoclinic system with P21 space group.. Functional groups were recognized and its vibrational behaviour has been studied from FT-IR analysis. Optical transparency of the crystal was tested by using the UV–vis spectrum. Fluorescence spectrum shows the peak at 528 nm. The second harmonic conversion efficiency of the crystal is nearly about 14.5 times greater to KDP and 5.8 times that of urea.

Influence of formic acid on optical and electrical properties of glycine crystal

A remarkable influence of formic acid on various properties of glycine single crystal has been investigated. The formic acid doped glycine crystals were grown by slow evaporation solution growth technique. The structural parameters of pure and doped glycine crystals were determined using single crystal x-ray diffraction technique. The presence of functional groups and the red shift caused by dopants were confirmed by FT-IR and FT-Raman spectroscopy. The UV–visible studies measures optical transparency, wide optical band gap (6.32 eV) and lower cutoff wavelength in glycine formic acid (GLFA) crystals. The Second Harmonic Generation measurement reveals high SHG efficiency in doped crystals compared with other glycine based NLO crystals. Dielectric studies were carried out and it explores low dielectric constant and dielectric loss for pure and doped samples. Ferro electric measurement was done to find the value of Remnant polarization (95.71 µC cm−2) and coercive field (583.71 kV cm−1) which have been enhanced for GLFA crystal.

Studies on Molecular Structure and Vibrational Spectra of NLO Crystal L-Glutamine Oxalate by DFT Method

Objectives: To explicate structural features of L-GLUTAMINE OXALATE (LGO) using vibrational spectroscopic methods and DFT computations. To identify the functional groups and hydrogen bonding interactions of the molecule by recording FTIR and FT-Raman spectra. To confirm NLO activity by performing SHG test. Methods/Statistical Analysis: Crystals were grown by slow evaporation method and characterized by powder X-Ray diffraction method. FTIR, FT-Raman, UV-Vis analysis and second harmonic generation test were predicted. DFT analysis using Gaussian’09 program package were performed to confirm the NLO properties theoretically. Findings: Lowering of HOMO-LUMO energy gap value explains the intramolecular charge-transfer interaction which indicates NLO property. Second Harmonic Generation of the sample shows good nonlinearity of the sample. Application/Improvements: LGO sample shows good NLO Properties and can be used in optical field.

Twisted intra-molecular charge transfer investigations of semiorganic triglycine phosphate single crystal for non linear optical applications

NLO materials are gaining importance in technologies such as optical communication, optical computing and dynamic image processing. Many NLO crystals grown by mixing amino acids with various organic and inorganic acids have been reported in the literature. Hence, glycine mixed semi-organic material will be of special interest as a fundamental building block to develop many complex crystals with improved NLO properties. A semi organic Single crystal of Triglycine Phosphate (TGP) which was grown and spectral analysis have been using FTIR and Raman spectral analysis. Natural Bond Orbital Analysis and the atomic natural charges are also predicted. HOMO LUMO energy gap value suggests the possibility of charge transfer within the molecule.

Growth, Properties, and Theoretical Analysis of M2LiVO4 (M\u2009=\u2009Rb, Cs) Crystals: Two Potential Mid-Infrared Nonlinear Optical Materials

Mid-Infrared nonlinear optical (Mid-IR NLO) crystals with excellent performances play a particularly important role for applications in areas such as telecommunications, laser guidance, and explosives detection. However, the design and growth of high performance Mid-IR NLO crystals with large NLO efficiency and high laser-damage threshold (LDT) still face numerous fundamental challenge. In this study, two potential Mid-IR NLO materials, Rb2LiVO4 (RLVO) and Cs2LiVO4 (CLVO) with noncentrosymmetric structures (Orthorhombic, Cmc21) were synthesized by high-temperature solution method. Thermal analysis and powder X-ray diffraction demonstrate that RLVO and CLVO melt congruently. Centimeter sized crystals of CLVO have been grown by the top-seeded solution growth method. RLVO and CLVO exhibit strong second harmonic generation (SHG) effects (about 4 and 5 times that of KH2PO4, respectively) with a phase-matching behavior at 1.064 μm, and a wide transparency range (0.33–6.0 μm for CLVO). More importantly, RLVO and CLVO possess a high LDT value (~28 × AgGaS2). In addition, the density functional theory (DFT) and dipole moments studies indicate that the VO4 anionic groups have a dominant contribution to the SHG effects in RLVO and CLVO. These results suggest that the title compounds are promising NLO candidate crystals applied in the Mid-IR region.

Crystal and optical perfection, linear and nonlinear optical qualities of β alanine β alaninium picrate (βAβAP) single crystal: a promising NLO crystal for optics and photonics applications

High quality and transparent organic nonlinear optical single crystal - β alanine β alaninium picrate (βAβAP) of 12 × 8 × 3 mm in dimensions was grown by slow evaporation method. The crystal structure was confirmed by single and powder X-ray diffraction studies. The perfection of the grown crystal is justified by High resolution XRD measurement. The strain of the crystal in grain boundary was calculated from the powder XRD pattern values. The Photo luminescence’s (PL) study is also investigated to predict the optical perfection of the crystal. Optical constants like, absorption coefficient, extinction coefficient, reflection, refractive index and optical band gap are calculated using UV–Vis absorption spectrum. Optical limiting method is involving to find the linear optical absorption. The birefringence of the crystal was measured in the visible region and it was found that birefringence is dependent of wavelength. The crystal was subjected to Z-scan measurement to prove the third order non linear optical property of the crystal. The thermal stability of the crystal against the high intense laser power is measured using laser damage threshold study.

Spectroscopic and DFT-based computational studies on the molecular electronic structural characteristics and the third-order nonlinear property of an organic NLO crystal: (E)-N′-(4-chlorobenzylidene)-4-methylbenzenesulfonohydrazide

Single crystals of (E)-N′-(4-chlorobenzylidene)-4-methylbenzenesulfonohydrazide (CBMBSH) have been grown by slow evaporation crystal growth method. The structure stabilizing intramolecular donor-acceptor interactions and the presence of the NH⋯O, CH⋯O and CH⋯C(π) hydrogen bonds in the crystal were confirmed by vibrational spectroscopic and DFT methods. The linear optical absorption characteristics of the solvent phase of CBMBSH were investigated using UV–Vis-NIR spectroscopic and TD-DFT approaches. The 2PA assisted RSA nonlinear absorption and the optical limiting properties of CBMBSH were studied using the open-aperture Z-scan method. The topological characteristics of the electron density have been determined using the quantum theory of atoms in molecules method.

1-((4-methylpiperazin-1-yl)(phenyl)methyl)naphthalen-2-ol: A novel Mannich base organic NLO crystal for the analysis of electro-optic applications

Organic 2-naphthol derived 1-((4-methylpiperazin-1-yl)(phenyl)methyl)naphthalen-2-ol Mannich base non linear optical single crystal was synthesized and crystallized successfully to investigate the suitability of the material for electro-optic device applications. Acetonitrile was used as a solvent to develop optically good quality single crystal. Slow evaporation technique was employed at room temperature. Single crystal X-ray diffraction confirms the existence of non-centrosymmetric nature of the grown crystal. The nonlinear optical property was tested by Kurtz and Perry powder technique and the SHG efficiency of MPN was found to be 1.03 times than standard KDP. The PL spectrum of MPN shows blue light emission which confirms the material as potential candidate for the opto-electronic applications. The load dependent hardness was measured by Vickers’ microhardness test and various parameters such as yield strength, stiffness constant were calculated and reported. The dielectric constant and dielectric loss were measured as a function of frequency for different temperatures. The low dielectric constant and dielectric loss confirms the lesser defects and quality of the grown crystal. A fraction amount of activation energy obtained from ac conductivity measurement is an added advantage for electro-optic device fabrication. The dark current of MPN that leads the photo current shows the negative photo conducting nature of the material which may be due to the reduction of charge carriers.

Experimental and theoretical second harmonic generation and photoluminescence from the pseudo-centrosymmetric dihydrochloride salt dihydrate of trans-1,2-bis(4-pyridyl)ethene

Here we have prepared a dihydrochloride salt dihydrate of the well-known trans-1,2-bis(4-pyridyl)ethene (BPE) featuring both photoluminescent and nonlinear optical properties. In its triclinic lattice (space group P1), BPE cations are stacked face-to-tail through π⋯π interactions between the spacer double-bonded carbons and the protonated pyridyl ring, with a slippage of 3.45 A always towards the same direction, which is common in other NLO crystals. The existence of inversion symmetry was suggested in its crystal structure, which was ruled out by the SHG emission centred at 487 nm upon excitation at 974 nm. While the fully optimized single molecule of the divalent BPE cation in the gas phase had almost null μ, βtot, βCT and βvec values calculated at the CAM-B3LYP/NLO-V//B3LYP/6-31G* level of theory, these values differed from zero in the crystal conformation. More interestingly, a ca. 4-fold increase in βtot, α and μ was observed for the π⋯π stacked four-molecules as found in its crystal structure. Lastly, this BPE material presents high photoluminescence emission centred at 425 nm under excitation at 366 nm, being therefore a multifunctional optical crystal form.

One-minute self-assembly of millimetre-long DAST crystalline microbelts via substrate-supported rapid evaporation crystallization

We propose a substrate-supported rapid evaporation crystallization method to rapidly self-assemble microbelts of DAST, a benchmark organic NLO crystal. DAST microbelt formation depends on substrate properties and surfactant.

Experimental and theoretical studies on new 7-(3,6-di-tert-butyl-9H-carbazol-9-yl)-10-alkyl-10H-phenothiazine-3-carbaldehydes

Synthesis of fused heterocyclic aldehydes with carbazole (CZ) structural motif linked at C-7 position on phenothiazines (PTZ), 7-(3,6-di-tert-butyl-9H-carbazol-9-yl)-10-butyl-10H-phenothiazine-3-carbaldehyde (1) and 7-(3,6-di-tert-butyl-9H-carbazol-9-yl)-10-hexyl-10H-phenothiazine-3-carbaldehyde (2) has been accomplished and are characterized through experimental and computational techniques. The optimized structure with their bonding aspects and vibrational frequencies of the same have been examined utilizing DFT-B3LYP technique with a basis set 6-311++G(d,p). In the optimized structures of 1 and 2, the bond lengths and bond angles are in accord with their corresponding reported analogous. The vibrational frequencies resulted from experimental as well as theoretical are in well accord with each other. Further, the results of polarizabilities, first order hyperpolarizabilities and dipole moment of 1 and 2 imply that these could be utilized for the preparation of NLO crystals which might generate second order harmonic waves.

Structural and solid state properties of l-leucinium p-toluenesulfonate monohydrate: an amino acid tosylate NLO crystal

An amino acid tosylate NLO crystal, l-leucinium p-toluenesulfonate monohydrate (LLPT) was synthesized and single crystal was grown by slow evaporation solution growth technique. The single crystal XRD study was employed to evaluate the structural properties and found good agreement with the reported values. The compound crystallized in the non-centrosymmetric orthorhombic cell setting with P212121 space group. The crystal packing is dominated by N–H···O and O–H···O hydrogen bonds leading to number of chain and ring motifs. These motifs are arranged in tandem along ab-plane of the crystal leading to alternate hydrophilic and hydrophobic layers along c-axis of the unit cell. Vibrational spectral measurements (FTIR and FT-Raman) shows the different functional groups and strength of the hydrogen bonds. The optical cutoff wavelength and absorbance studies of the compound have been examined by UV–Vis–NIR absorbance spectrum. The material did not show any significance absorption in the entire visible region and cutoff wavelength at 283 nm. The emission property of the material was analyzed by Photoluminescence study and the material has ultraviolet emission. TGA/DTA studies show that the material became anhydrous around 73 °C and start melting at 169 °C. Vicker’s microhardness test show that LLPT belongs to soft category material. The dielectric behaviour and solid state parameters of the compound were analyzed at room temperature by dielectric studies with varying frequency. Kurtz and Perry SHG tests confirms the materials ability to green emission when exposed to a laser with wavelength of 1064 nm and the SHG efficiency of 0.5 times the KDP.

Growth and non-critical phase-matching frequency conversion properties of LaxY1−xCOB crystals

A new series of nonlinear optical crystals LaxY1−xCa4O(BO3)3 (LaxY1−xCOB) with multiple components were grown by using the traditional Czochralski pulling method. X-ray powder diffraction and single-crystal X-ray diffraction experimental results proved that all these crystals formed in the LaxY1−xCOB solid solution state with a monoclinic structure of space group Cm. The optical birefringence was found to be adjustable by changing the compositional parameter x for the LaxY1−xCOB crystals. Taking advantage of the optical parametric oscillator laser, the non-critical phase-matching (NCPM) second-harmonic-generation (SHG) and third-harmonic-generation (THG) wavelengths along the Y-axis were determined at ambient temperature. In addition, the relationships between and among the optical birefringence, NCPM wavelength and crystal structure were discussed, and the NCPM SHG and THG of the 1064 nm laser were further achieved from the La0.120Y0.880COB and La0.140Y0.860COB crystals by adjusting the temperature, respectively. Using a 1064 nm Nd:YAG laser as the fundamental light source, the angular acceptance, temperature acceptance, and optical conversion efficiencies were determined and found to be on the order of 107.6 mrad, 18.3 °C and 48.8% for SHG of the La0.120Y0.880COB crystal, respectively, and 126.8 mrad, 68.6 mrad, 10.6 °C and 32.4% for THG of the La0.140Y0.860COB crystal, respectively. It is demonstrated that LaxY1−xCOB is a promising NLO crystal for NCPM frequency conversion applications in the visible and ultraviolet spectral regions.

Synthesis, growth and optical studies of novel organometallic NLO crystal: Calcium bis-thiourea chloride

A novel organometallic crystal calcium bis-thiourea chloride (CBTC) has been synthesized and confirmed by means of EDX and FT-IR analysis. The (25×9×10)mm3 CBTC crystal has been grown from aqueous solution by slow solution evaporation technique. The UV–visible spectral study has been carried in the range of 200–900nm to assess the optical transparency of CBTC crystal. The optical constants such as band gap, optical conductivity, refractive index and reflectance of grown crystal have been evaluated using the transmittance data. The color centered fluorescence behavior of grown crystal has been explored in visible region. The Z-scan technique has been employed to determine the negative third order nonlinear refraction behavior of CBTC crystal. The magnitude of third order nonlinear refraction (n2), nonlinear susceptibility (χ3), nonlinear absorption (β) and FOM of grown crystal has been calculated using the Z-scan data. The χ3 of magnitude 3.56×10−5esu confirms the strong polarizing nature of CBTC crystal. The Kurtz-perry test confirmed the SHG efficiency of CBTC crystal is 1.15 times higher than KDP crystal material.

Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution

Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal.

Growth and characterization of novel organic 3-Hydroxy Benzaldehyde-N-methyl 4 Stilbazolium Tosylate crystals for NLO applications

The 3-Hydroxy Benzaldehyde-N-methyl 4-Stilbazolium Tosylate (3- HBST) is a new organic NLO crystal and it is a new derivative in stilbazolium tosylate family. In this work we have synthesized 3-HBST and the single crystal was grown by conventional slow cooling method. The structure and lattice parameters of the grown crystal were determined by the single crystal X-ray diffraction (XRD) technique and it is exhibiting good crystalline nature which is observed from the powder XRD. In order to check the crystalline quality the rocking curve was recorded using multi crystal X-ray diffractometer. The functional groups were identified from both FTIR and NMR spectral analyses. The π–π* and n–π* optical transition energy levels were estimated from the absorption peaks. The NLO property was confirmed by measuring relative SHG efficiency by Kurtz powder test; it shows 24 times higher SHG efficiency than that of urea. In order to test the mechanical stability the Vickers and Knoop micro hardness measurement were carried out and found that the micro hardness number decreases with increasing load. The melting point was determined from Differential Scanning Colorimetry (DSC).

The effect of succinic acid on the physico-chemical characterization studies of benzil NLO single crystal

In the present work, an attempt is made to study the influence of succinic acid on the physio-chemical characterization properties of benzil NLO single crystals. Slow evaporation technique has been employed to harvest pure benzil (PB) and succinic acid doped benzil (SAB) crystals. The dimensions of PB and SAB crystals were found to be 21mm×4mm×4mm and 13mm×4mm×3mm, respectively. The as grown crystals were characterized by XRD, FTIR, UV–vis, TG//DSC, microhardness, 1H and 13C and dielectric measurements. The presence of dopants has been confirmed by spectral analysis and by XRD. The lattice parameters of the grown crystals were determined by XRD analysis. The absorbance and mechanical strength of pure and doped crystals were assessed by UV–vis and Vickers microhardness analysis. The various functional groups in the molecule were estimated by FTIR analysis. The presence of hydrogen and carbon bonded network were elucidated using 1H and 13C NMR spectral analysis. The thermal stability and the phases of decomposition were measured by TG and DSC analysis. The effect of polarization on the doping of succinic acid into benzil NLO crystal was studied by dielectric measurements. The presence of SHG was identified by Kurtz and Perry test.

Growth and characterization of a new organic NLO crystal: Guanidine acetate single crystals

Single crystals of Guanidine acetate, an organic NLO material, have been successfully grown by slow evaporation technique, and are reported for the first time. The cell parameters and the crystallinity are determined from the single crystal X-ray diffraction studies. FTIR studies have been carried out to identify functional groups present in the crystal. Thermal and optical transmission studies have been made on the grown crystals. The grown crystals were subjected to micro hardness studies. Kurtz powder SHG measurement confirms the NLO property of the grown crystal.

Growth and characterization of NLO crystal: L-leucine phthalic acid potassium iodide

Abstract A new semi-organic non linear optical crystal, L-leucine phthalic acid potassium iodide (LLPPI) has been grown from an aqueous solution by slow evaporation method. The grown crystals were subjected to different characterizations, such as single crystal XRD, FT-IR, UV-Vis, TGA, SEM, EDAX, micro hardness, dielectric and powder SHG. Single crystal structure was determined from X-ray diffraction data and it revealed that the crystal belongs to triclinic system with the space group P1. The vibrational frequencies of various functional groups were derived from FT-IR spectrum. Thermal stability of the grown crystal was investigated by TG-DTA studies and it was observed that the crystal was thermally stable up to 192 °C. Optical absorption study was carried out and a good transparency in the entire visible region was observed at the lower cutoff wavelength of 227 nm. Dielectric study was performed as a function of frequency and normal dielectric behavior was observed. The micro hardness test was carried out and the load dependent hardness was measured. Kurtz powder method was employed to explore the NLO characteristics of the grown crystal.

Growth and characterization of noncentrosymmetric single crystals of l-Argininium-4-nitro Phenolate Monohydrate (LARP): A potential second order nonlinear optical material

A potential second order NLO material l-Argininium-4-nitro Phenolate Monohydrate (LARP) was grown by the slow evaporation technique. The grown organic NLO crystals were subjected to various studies such as single crystal XRD, UV–Visible spectrum, photoluminescence, Second Harmonic Generation (for various particle sizes) and laser damage threshold (LDT) studies. The LARP crystal belongs to orthorhombic system with noncentrosymmetric space group P212121. Piezoelectric charge coefficients of the grown crystal have been determined. The dielectric studies were performed at different temperatures and frequencies to analyze the electrical properties. The microhardness measurements were used to investigate the mechanical property of the grown crystal.