Growth and characterization of GSZS crystals with enhanced transparency window for non linear optical applications

Transparent crystals of novel non-linear optical material comprising of glycine sodium-zinc sulfate (GSZS) have been grown in our laboratory from solution by slow evaporation technique. Transparent crystals of dimensions (8 × 7 × 4 mm³) have been obtained in 3-4 weeks time. The solubility in water shows linear variation in temperatures range from 300 K to 350 K. The GSZS crystal exhibits orthorhombic symmetry with a = 5.418 A.U., b = 6.084 A.U and c = 3.497 A.U. The intense XRD peak is found at 25.43°. The presence of functional groups has been studied by FTIR analysis and verified by laser Raman spectra. Lower cutoff wavelength and enhanced transparency window with a typical energy gap of 5.85 eV are suggested by the UV measurements. The second harmonic generation (SHG) efficiency of GSZS is found to be 0.62 times than that of standard KDP using modified Kurtz and Perry technique. The GSZS crystal exhibits a normal dielectric behavior.     

Structural, optical and electrical studies on amino acid based new GBC crystals having non linear optical response

Transparent crystals of α-glycine with barium nitrate and calcium nitrate (GBC) have been grown from aqueous solution by slow evaporation technique at room temperature. Crystals of size 22 × 25 × 4 mm³ have been obtained in 3-4 weeks time. The solubility of GBC has been determined in water. The grown crystal belongs to orthorhombic system with cell parameters a = 12.7321 A.U, b = 13.7752 A.U and c = 8.6002 A.U with unit cell volume of 1508.36 (A.U)³. Comparative IR and Raman studies indicate a molecule with a lack of center of symmetry. A wide transparency window useful for optoelectronic applications is indicated by the UV Studies. Using Nd:YAG laser (1064 nm), the optical second harmonic generation (SHG) conversion efficiency of GBC is found to be 0.702 times than that of standard KDP. On exposure to light the GBC crystals exhibit positive photoconductivity. I-V characteristics, dielectrics studies, electrical and Vickers micro hardness measurement have been carried out. The GBC crystal exhibits more mechanical strength compared to the reported GSN crystals.     

Growth, structural and optical studies on amino acid based new GSB crystals having non-linear optical characteristics

Transparent crystals of α-glycine with sodium nitrate and barium nitrate (GSB) have been grown from aqueous solution by slow evaporation technique at room temperature. Crystals of size 11 × 7 × 4 mm³ have been obtained in 3-4 weeks time. The solubility of GSB has been determined in water. The grown crystal belongs to orthorhombic system with cell parameters a = 4.684 a.u., b = 12.184 a.u. and c = 10.969 a.u. with unit cell volume of 625.99 (a.u.)³. Comparative IR and Raman studies indicate a molecule with a lack of centre of symmetry. A wide transparency window useful for optoelectronic applications is indicated by the UV studies. Using Nd-YAG laser (1064 nm), the optical second harmonic generation (SHG) conversion efficiency of GSB is found to be 0.648 times that of standard KDP. On exposure to light the GSB crystals exhibit positive photoconductivity. I-V characteristics, dielectrics studies and Vickers micro hardness measurement have been carried out. The GSB crystal exhibits more mechanical strength compared to the reported GSN crystals.     

Synthesis,growth and characterization of non-linear optical material: l-Tryptophan p-nitrophenol (LTPNP) single crystal

A new nonlinear optical organic crystal l-tryptophan p-nitrophenol (LTPNP) of dimension 19 mm × 2 mm × 1.5 mm has been grown from an aqueous solution for the first time by slow evaporation technique at ambient temperature. The crystal structure of LTPNP was confirmed by single crystal X-ray diffraction. LTPNP crystallizes in non-centrosymmetric monoclinic system with space group P₂₁. The recorded FTIR spectrum confirms the presence of various functional groups in the grown crystal and confirms the formation of LTPNP. Thermal stability and melting temperature of the LTPNP crystal were identified from TG/DTA analysis. The optical absorption study confirms the suitability of the crystal for device applications. LTPNP exhibits SHG efficiency over 1.7 orders of magnitude higher than that of urea and 4 orders of magnitude higher than that of KDP.     

l-Cystine hydrochloride: A novel semi-organic nonlinear optical material for optical devices

A new semi-organic nonlinear optical (NLO) material l-cystine hydrochloride (LCHCl) was grown in large size measuring 19 × 5 × 3 mm³ by slow solvent evaporation technique for the first time in literature. The cell parameter values were determined by single crystal X-ray diffraction studies. Fourier Transform Infrared spectroscopic analysis was carried out on the grown sample to ascertain the fundamental functional groups. Thermal behavior of the grown LCHCl sample was analyzed by TG & DTA analysis. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. The optical transmission studies and second harmonic generation (SHG) efficiency studies justified the device quality of the grown crystal and the SHG study reveals that the grown sample has nearly 1.2 times higher efficiency than that of potassium dihydrogen phosphate (KDP), a well known NLO material.     

Growth, structural, optical and electrical behavior of glycine potassium nitrate (GPN) crystal with non-linear optical response

New trapezoidal, non-linear optical crystals of glycine potassium nitrate (GPN) have been grown by slow cooling from solutions with an initial pH of 4.3. Chemical composition, phase formation and functional groups have been verified by CHN, EDAX, XRF, NMR, XRD, FTIR and Raman studies. UV studies show a much lower cut off wavelength (195 nm) compared to the much investigated glycine sodium nitrate (GSN). The powder SHG efficiency of GPN is found to be 0.6 times compared to that of potassium dihydrogen phosphate (KDP). Cut and polished crystals exposed to light indicate positive photoconductivity. Electrical conductivity studies show an activation energy of 0.16 eV and the dielectric loss is found to decay drastically at higher frequencies (1 MHz) which is desirable in electronic applications. Vickers microhardness studies indicate a Mayer's index value of 2.78. Well resolved, elongated and oriented etch pits have been observed on the side habit face (220) treated in glacial acetic acid for 5 s. Typical circular features resisting the formation of etch pits representing impurity elements have been observed on the cleavage faces. Moisture has been traced on the surface of the crystals subjected to heat treatment.     

Increased temperature bandwidth of second harmonic generator using two KTiOPO4 crystals cut at different angles

We report a second harmonic generator (SHG), whose temperature full-width of half-maximum (FWHM) bandwidth is significantly increased by replacing a single long type-II phase-matched KTiOPO₄ (KTP) crystal with two shorter crystals, which are cut at slightly different phase-matching angles. The total length of the two crystals is the same as that of the longer ones. The experimental results show that the measured temperature FWHM bandwidth of the SHG is significantly increased from 11.8 °C in the single 7 × 7 × 10 mm³ KTP crystal to 60.2 °C when the single KTP is replaced with two of 7 × 7 × 5 mm³ KTP crystals whose phase-matching angle are 1.0° apart. Such a SHG allows stable output when it is operated in the environment of very rough temperature condition.     

Thermal, mechanical, electrical, linear and nonlinear optical properties of a nonlinear optical l-ornithine monohydrochloride single crystal

Optically transparent semiorganic nonlinear optical bulk single crystal of l-ornithine monohydrochloride (LOMHCL) of dimension 11×3×2 mm³ has been grown from its aqueous solution by slow solvent evaporation technique. The grown crystal was characterized by powder X-ray diffraction to confirm the crystal structure. Investigation has been carried out to assign the vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopy technique. Thermal behavior of the grown crystals was studied by thermogravimetric analysis. The second harmonic generation (SHG) efficiency of LOMHCL was determined by Kurtz and Perry powder technique. The optical absorption study confirms the suitability of the crystal for device applications. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. Dielectric and photoconductivity studies are also carried out for the grown samples.     

Growth, thermal, optical and birefringence studies of semiorganic nonlinear optical thiosemicarbazide cadmium chloride monohydrate (TCCM) single crystals

A semiorganic nonlinear optical material (thiosemicarbazide cadmium chloride monohydrate) (TCCM) was synthesized and single crystals was grown from aqueous solution by slow evaporation method at ambient temperature. Crystal of average size up to 5×4×3 mm³ were harvested and characterized by powder X-ray diffractometry (XRD) and Fourier transfer infrared (FTIR) technique to confirm the identity of the compound formed. The thermal stability was analyzed by TG/DTA. The birefringence values (Δ_n) were determined in the wavelength region 540-6500 Å. The second harmonic generation (SHG) from the materials was confirmed using Nd:YAG laser.     

Studies on the optical and mechanical properties of organic nonlinear optical 1-(4-fluorostyryl)-4-nitrostilbene (FNS) single crystal

A new organic nonlinear optical material 1-(4-fluorostyryl)-4-nitrostilbene (FNS) has been synthesized and single crystals of FNS were grown using solvent evaporation solution growth technique (SESGT) by 2-butanon solvent. Single crystal x-ray diffraction analysis reveals the unit cell parameters of the grown crystal are a = 9.494(4) Å, b = 9.864(2) Å, c = 19.501(7) Å and it belongs to monoclinic system with noncentrosymmetric space group. Optical transmittance of the grown crystal has been studied by UV-Vis-NIR spectrum. The optical properties of FNS have been studied by means of optical transmittance measurements in the wavelength range of 190–1100 nm The optical constants were calculated from the optical transmittance (T) data such as refractive index (n), extinction coefficient (k) and reflectance (R). The optical band gap (E_g) of FNS is 3.27 eV with direct transition. The complex dielectric (?) constant of the grown FNS crystal was determined. The second harmonic generation (SHG) efficiency of the grown FNS crystal has been studied by using Kurtz-Perry powder technique and it shows 12 times relatively greater than KDP.     

Synthesis,growth and physicochemical properties of an organometallic nonlinear optical crystal: Mercury cadmium chloride thiocyanate

SCN⁻ ligand based organometallic non-linear optical mercury cadmium chloride thiocyanate (MCCTC) crystals are grown from water plus methanol mixed solvent by slow evaporation technique. The grown crystals are confirmed by single crystal X-ray diffraction analysis. MCCTC exhibits a SHG efficiency which is nearly 17 times more than that of KDP. The dielectric constant, dielectric loss and ac conductivity measurements of the sample have been carried out for different frequencies (100 Hz to 5 MHz) and, temperatures (308–388 K) and the results are discussed. Photoconductivity study confirms that the title compound possesses negative photoconducting nature. The surface morphology of MCCTC was also investigated.     

Growth and characterization of a new organic NLO material: Glycine nitrate

Single crystals of glycine nitrate [(C₂H₆NO₂)⁺ · (NO₃)⁻] were grown using submerged seed solution method. The crystals were characterized by using single crystal X-ray diffraction and density measurements. Spectroscopic, thermal and optical studies were carried out for analyzing the presence of the functional groups, thermal stability, decomposition and transparency of the sample. These studies showed that the crystals are thermally stable upto 145 °C and transparent for the fundamental and second harmonic generation of Nd:YAG (λ = 1064 nm) laser. Second harmonic generation (SHG) conversion efficiency was investigated to explore the NLO characteristics of this material. Microhardness and dielectric studies were also carried out.     

Crystal growth,structural, linear and nonlinear optical studies of 4-methyl-4′-N’-methylstilbazolium tosylate single crystals

Organic 4-methyl-4′-N’-methylstilbazolium tosylate, a new derivative of the stilbazolium tosylate family compound was synthesized by condensation method. The optical quality single crystals with dimension 5 mm × 4 mm × 2 mm were grown by slow evaporation technique at 40 °C. The crystal system and lattice parameters were found from single crystal X-ray diffraction studies. The optical transmittance, cut-off wavelength (402 nm) and band gap energy (3.09 eV) were estimated by UV–visible studies. The surface laser damage threshold study was carried out for MMST crystal using Nd:YAG laser. The third-order nonlinear optical susceptibility (χ³) for MMST crystal was estimated by employing Z-scan technique using 1064 nm laser.     

Optical behaviour of VTE treated near stoichiometric LiNbO3 crystals

Near stoichiometric LiNbO₃ crystal wafers of thickness up to 2 mm were prepared by vapour transport equilibration technique (VTE) at various process temperatures. Crystals were characterised by measurement of the UV absorption edge, refractive index, second harmonic generation (SHG) efficiency, and conoscopy pattern analysis. The comparison of VTE treated crystals show that the blue shift in cut off wavelength occurred with the increasing process temperature (i.e. increasing Li/Nb ratio). The refractive indices were found decreasing with increasing process temperature of VTE samples. The SHG efficiency increases in the range of 1.98-2.3 times for the VTE processed samples with respected to congruent crystals. Conoscopy pattern reveals the optical homogeneity of the VTE treated crystal.     

Thermally induced second harmonic generation in PbO-B2O3 glasses

Second harmonic generation (SHG) was observed in PbO-B₂O₃ glasses after heat treatment at elevated temperature followed by rapid quenching in water at room temperature (about 25 °C). According to the results of thermally stimulated depolarization current (TSDC) measurement and XRD patterns, no depletion layer or crystals was found in the rapidly quenched glass samples. The thermally induced nonlinear layer is located in the regions extended from the surface and 8 μm into the bulk. The possible mechanism responsible for the SHG is that the bond deformation of glass structure induced by stress gradient breaks the inversion symmetry of glass. The influencing factors of the SH intensity are also discussed.     

Anisotropy of second-order nonlinear optical susceptibilities of arsenic triiodide-sulfur addition complex: AsI3 · 3S8

We report the anisotropic linear and second-order nonlinear optical (NLO) properties of arsenic triiodide-octa-sulfur (1:3) adduct, AsI₃ · 3S₈, which spontaneously crystallizes in the trigonal rhombohedral non-centrosymmetric space group R3m. The trigonal symmetry of the AsI₃ · 3S₈ molecule coincides with the crystal symmetry. The crystals are optically uniaxial with n_o/n_e of about 1.2 and show dichroism at the UV-visible wavelengths. Second harmonic generation (SHG) tensor elements were determined from Maker fringes measured with an Nd:YAG laser (∼10 ns pulse, 1064 nm). The coefficient d_222,eff = 32.0 pm/V for the light polarized parallel to the layers of iodine and sulfur atoms in the AsI₃ · 3S₈ crystal ab plane is markedly larger than d₃₃₃ = 11.6 pm/V for the polarization of light parallel to the crystal c axis. The anisotropy parameter, defined as the d_222,eff/d₃₃₃ ratio, is about 2.7 for the AsI₃ · 3S₈ crystal, smaller than that for the isomorphous CHI₃ · 3S₈ crystal (7.3) but larger than for the SbI₃ · 3S₈ crystal (0.7). Highly anisotropic components of the first hyperpolarizability tensor of an AsI₃ · 3S₈ molecule, β, were derived from the quadratic nonlinear susceptibility tensor of the crystal.     

Characterization studies on the additives mixed l-arginine phosphate monohydrate (LAP) crystals

l-arginine phosphate monohydrate (LAP), potassium thiocyanate (KSCN) mixed LAP (LAP:KSCN) and sodium sulfite (Na₂SO₃) mixed LAP (LAP:Na₂SO₃) single crystals were grown by slow cooling technique. The effect of microbial contamination and coloration on the growth solutions was studied. The crystalline powders of the grown crystals were examined by X-ray diffraction and the lattice parameters of the crystals were estimated. From the FTIR spectroscopic analysis, various functional group frequencies associated with the crystals were assigned. Vickers microhardness studies were done on {1 0 0} faces for pure and additives mixed LAP crystals. From the preliminary surface second harmonic generation (SHG) results, it was found that the SHG intensity at (1 0 0) face of LAP:KSCN crystal was much stronger than that of pure LAP.     

Studies on amino acid picrates: Crystal growth,structure and characterization of a new nonlinear optical material l-isoleucinium picrate

A series of l-amino acids, isoleucine, valine, glutamine, methionine, arginine, cystine and aspargine are employed to form picrates with picric acid (1:1). A comparison of cell parameters reveals that expected picrates are formed only in the case of l-valine and l-isoleucine. l-Isoleucinium picrate (LIP), a new nonlinear optical material was grown from aqueous medium by the slow evaporation of equimolar mixture of l-isoleucine and picric acid. The structure of the grown crystal as determined by single crystal XRD diffraction analysis reveals that it belongs to the monoclinic system with space group P2₁ and the cell parameter values are, a = 9.970(3) Å; b = 6.425(2) Å; c = 12.871(4) Å; β = 109.54(3)°; V = 770.0(4) Å³; Z = 2. The presence of functional groups in the LIP is confirmed by FT-IR vibrational patterns and the good crystallinity indicated by powder X-ray diffraction method. The relative second harmonic generation (SHG) efficiency measurements reveal that the LIP is a highly efficient nonlinear optical (NLO) material having an activity 16 times as that of the reference material potassium dihydrogen phosphate. The optical transparency has been studied using UV–vis spectrophotometer and the absorption is minimum in the visible region. Thermogravimetric and differential thermal analyses reveal the purity of the sample and no decomposition is observed up to the melting point.     

The effect of MgO doping on optical properties of LiNbO3 single crystals

Undoped and MgO doped Lithium niobate single crystals were grown by the Czochralski technique. Comparative study of the optical properties of undoped and 7 mol% MgO doped LiNbO₃ crystal was undertaken. The effect of doping on refractive indices as well as second harmonic generation has been experimentally analyzed. The results of the polarization characteristics of second harmonic generation (SHG) support the major contribution of Li-O bonds to optical nonlinearity. MgO doping reduces the number of localized excitons and the grown LiNbO₃ crystal approaches the stoichiometric composition. This causes blue shift in the absorption edge of the crystals.     

Generation of 532 nm laser radiation and phase matching properties of organic nonlinear optical material

Organic nonlinear optical single crystal of l-asparagine-l-tartaric acid (LAsT) was grown by slow evaporation technique at room temperature. The grown crystal was confirmed by single crystal X-ray diffraction and FT-IR studies. The direct band gap energy was found to be 5.4 eV. The SHG efficiency of the sample is 3 times higher than that of KDP crystal. The laser damage threshold of the grown crystal was 5.7 GW/cm². The grown crystal was thermally stable up to 141 °C. Low dielectric constant at higher frequency was found by dielectric measurements. The activation energy was calculated from Arrhenius relation and it was found to be 0.088 eV. Negative photoconducting nature was obtained by photoconductivity measurements.