Third order optical non-linear (Z-scan), birefringence,photoluminescence, mechanical and etching studies on melaminium levulinate monohydrate (MLM) single crystal for optical device applications

Z-scan studies on the grown crystal was investigated by diode-pumped Nd; YAG laser. Nonlinear refractive index (n₂) and third-order nonlinear optical susceptibility (χ³) values of MLM were found to be −1.0 × 10⁻⁸ cm²/W and 1.36 × 10⁻⁶ esu respectively. Powder X-ray diffraction analysis depicted that the crystal belongs to monoclinic system with space group P2₁/c. Birefringence study revealed the optical dispersion behavior of MLM crystal. Linear refractive index on (10-1) plane was measured by prism coupling technique and was estimated to be 1.4705. Hardness study was carried out along three different planes which exhibit hardness anisotropy of 41.11%. Meyer's index values of the grown crystal for the (10-1), (010) and (111) planes were found to be 2.39, 2.61 and 2.04 respectively. Etching studies on the prominent (10-1) growth plane was explained by two dimensional layer growth mechanisms. Photoluminescence study was performed on MLM crystal to explore its efficacy towards optical device fabrications.     

Effect of Ni on the structural, optical, thermal and dielectric properties of ADP single crystals

The effects of the addition of Ni²⁺ on the growth and various properties of ammonium dihydrogen phosphate single crystals grown from aqueous solution by the slow evaporation method have been studied. The grown crystals were subjected to HRXRD, UV-Vis, TG/DTA and dielectric studies. The structural perfection of the grown crystal has been analyzed by high resolution X-ray diffraction rocking curve measurements. UV-Vis studies show that the grown crystal has good transparency in the entire visible region which is an essential requirement for a nonlinear crystal. Higher decomposition temperature was observed from TG/DTA. Dielectric constant and dielectric loss were measured for the grown crystal for different frequencies and temperatures.     

A study on optical, thermal, mechanical, dielectric, piezoelectric and NLO properties of unidirectional ammonium chloride added ammonium dihydrogen phosphate crystal

<0 0 1> directed ammonium dihydrogen phosphate single crystal with the addition of 1 mol% of ammonium chloride in the mother solution has been grown by Sankaranarayanan-Ramasamy method. The grown crystal has cylindrical morphology with good optical quality. It has good thermal stability up to 200 °C. Higher mechanical stability was observed in ammonium chloride added crystal compared to pure crystal. Moreover, the addition of ammonium chloride improves the quality and yields highly transparent crystal in minimum duration of growth. Good piezoelectric behaviour was observed for the grown crystal. Low dielectric loss shows that the grown crystal contains minimum defects. The optical transmission study and the powder SHG measurement show the suitability of the ingot for nonlinear optical applications.     

Studies on lithium l-ascorbate dihydrate: An interesting chiral nonlinear optical crystal

Lithium l-Ascorbate dihydrate (LLA) is a new metal organic nonlinear optical crystal belonging to the saccharide family. Single crystals of LLA were grown from aqueous solution. Solubility of the crystal has a positive temperature coefficient facilitating growth by slow cooling. Rietveld refinement was used to confirm the phase formation. The crystal has prismatic habit with (010), (001) and (10−1) prominent faces. Thermal analysis shows that the crystal is stable up to 102 °C. Transmission spectrum of the crystal extends from 302 nm to 1600 nm. Dielectric spectroscopic analysis revealed Cole–Cole behaviour and prominent piezoelectric resonance peaks were observed in the range of 100–200 kHz. Second harmonic generation (SHG) conversion efficiency of up to 2.56 times that of a phase matched KDP crystal was achieved when the (010) plate of LLA single crystal was rotated about the +ve c axis, by 9.4° in the clockwise direction. We also observed SHG conical sections which were attributed to noncollinear phase matching. The observation of the third conical section suggests very high birefringence and large nonlinear coefficients. A detailed study of surface laser damage showed that the crystal has high multiple damage thresholds of 9.7 GW cm⁻² and 4.2 GW cm⁻² at 1064 nm and 532 nm radiation respectively.     

Optical,mechanical and transport properties of unidirectional grown l-tartaric acid bulk single crystal for non-linear optical application

Good optical quality bulk single crystal of l-tartaric acid has been grown by directional solidification crystal growth method from aqueous solution. Crystal of dimension 77 mm length and 12 mm diameter has been grown at a growth rate of 2.5 mm day⁻¹ which is the maximum size and growth rate achieved so far. The grown crystal was confirmed by powder XRD analysis and the presence of the functional groups in the crystal lattice was confirmed by Fourier transform infrared spectral analysis. Transmission spectral analysis shows that the crystal has more than 90% of transmittance in visible and near infrared region which exhibits the good optical quality of the crystal. The optical band gap was estimated to be 4.8 eV and it shows indirect optical transition. Thermal analysis shows the crystal to be thermally stable up to 172 °C and the load variation of the hardness has been explained on the basis of normal indentation size effect from microhardness study.     

Growth and characterization of a new semi-organic nonlinear optical sodium paranitrophenolate paranitrophenol dihydrate single crystal

A new semi-organic nonlinear optical sodium paranitrophenolate paranitrophenol dihydrate single crystal is grown successfully using methanol as solvent by slow evaporation technique to dimensions of 14 × 5 × 4 mm³ in a period of 7 days. The grown crystal is characterized by X-ray diffractometry and UV-Visible spectral analysis. X-ray diffraction data reveals that the crystal belongs to monoclinic system with space group C2. Optical absorption studies illustrate low absorption in the entire UV and Visible region. The second harmonic generation (SHG) efficiency of the crystal measured by Kurtz's powder technique infers that the crystal has NLO coefficient 5 times greater than that of KDP crystal. Remarkable mechanical strength with the work hardening coefficient less than 2 and thermal stability up to 120 °C of the grown crystal is reported.     

Investigation of SR method grown 0 0 1 directed KDP single crystal and its characterization by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, optical and hardness studies

0 0 1 directed potassium dihydrogen orthophosphate (KDP) single crystal was grown by Sankaranarayanan–Ramasamy (SR) method. The 0 0 1 oriented seed crystals were mounted at the bottom of the platform and the size of the crystals were 10 mm diameter, 110 mm height. Two different growths were tried, in one the crystal diameter was the ampoule's inner diameter and in the other the crystal thickness was less than the ampoule diameter. In the first case only the top four pyramidal faces were existing whereas in the second case the top four pyramidal faces and four prismatic faces were existing through out the growth. The crystals were grown using same stoichiometric solution. The results of the two growths are discussed in this paper. The grown crystals were characterized by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, UV–vis spectroscopy and microhardness studies. The HRXRD analysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. Laser damage threshold value has been determined using Nd:glass laser operating at 1054 nm. The damage threshold for the KDP crystal is greater than 4.55 GW cm⁻². The dielectric constant was higher and the dielectric loss was less in SR method grown crystal as against conventional method grown crystal. In thermal analysis, the starting of decomposition nature is similar in SR method grown KDP crystal and conventional method grown crystal. The SR method grown KDP has higher transmittance and higher hardness value compared to conventional method grown crystals.     

Physicochemical properties of organic nonlinear optical crystal for frequency doubling: Glycine acetamide

Non-linear optical (NLO) crystal of glycine acetamide (GA) is synthesized and grown in aqueous solution by slow evaporation technique. The cell parameters of the grown crystal are identified from single crystal XRD and the functional groups are confirmed in vibrational analysis. Temperature dependence of the material is probed using TGA/DTA. Mechanical strength of the grown material is tested by Hardness studies. UV-VIS-NIR spectral study explains the transmission ability of the crystal in visible range also the photoluminescence spectrum explains the transition mechanism of ions. The NLO activity of the crystal is confirmed by Kurtz power technique.     

Synthesis, growth, structural, optical, photoconductivity and dielectric studies on potassium p-nitrophenolate dihydrate: A new semiorganic nonlinear optical material

Potassium p-nitrophenolate dihydrate, a potential semiorganic nonlinear optical material, has been synthesized and grown by slow evaporation technique at room temperature. Single crystal X-ray analysis presents an unprecedented bonding between ions in the crystal with acentric structure. In the new structural investigation, p-nitrophenolate instead of producing bond between phenolic O⁻ and K⁺, it seems to put nitro group in bonding with the metal ion. Optical absorption shows excellent transmission in the entire visible and near-infrared region. Room temperature photocurrent, transport properties are carried out in order to enhance the application for second harmonic generation and opto-electronic devices. Dielectric constant is found to be independent at higher frequencies. The crystal possesses prominent positive photoconduction in the presence of photoactive centers formed with trap energy level. The nonlinear optical activity is confirmed by Kurtz powder test.     

Growth and spectroscopic analysis of semi-organic bisthiourea sodium fluoride crystal

A semi-organic bisthiourea sodium fluoride (BTSF) is synthesized at ambient temperature and the single crystal of bisthiourea sodium fluoride is grown in slow evaporation technique using water as solvent. The cell parameters of the grown crystal are estimated from single crystal XRD analysis and also unambiguous assignments of fundamental modes of various molecular groups are made from the recorded FTIR and FT-Raman spectra. The thermal stability of the grown crystal is investigated using thermo-gravimetric analysis studies. Optical transmittance percentage of the grown crystal is measured from UV-VIS studies.     

Influence of defects on the quality and optical studies of sodium p-nitrophenolate dihydrate, a nonlinear optical material

Nonlinear optical material of sodium p-nitrophenolate dihydrate was synthesized by employing the technique of controlled evaporation and the effect of temperature on growth morphology was investigated. Single crystal XRD analysis confirms that the crystals with different morphologies have the same lattice parameters. The high-resolution X-ray diffraction curves recorded by a multicrystal X-ray diffractometer revealed the presence of very low angle tilt boundaries. The green emission band at 524 nm is due to the existence of defects on the crystal which corroborated with HRXRD studies. The wide band gap of the SPND crystals confirms the large transmittance in the visible region.     

Tuning the dielectric properties of thiourea analog crystals for efficient nonlinear optical applications

Materials with low dielectric constant have attracted a great deal of interest in the field of nonlinear applications and microelectronic industry. Metal complexes of thiourea with group II transition metals (Zn, Cd) as central atom and period III elements (S, Cl) were synthesized by chemical reaction method and single crystals were grown from aqueous solution by slow evaporation method. By parallel plate capacitor technique, the dielectric response, dissipation factor, ac conductivity and impedance of virgin and metal complexes have been studied in the frequency (100 Hz to 5 MHz) and temperature (303-423 K) ranges. Metal complexes of thiourea with cadmium substitute have a low dielectric constant less than 10. Also the presence of chlorine in the metal complex induces noncentro symmetric structure. Hence the role of group II transition metals and period III elements in tuning the dielectric properties for efficient nonlinear applications has been studied.     

Organic nonlinear optical crystal 4-hydroxy-N-methyl 4-stilbazolium besylate synthesis and characterization

Novel organic nonlinear optical material 4-hydroxy-N-methyl 4-stilbazolium besylate has been synthesized and 7 mm × 5 mm × 3 mm size crystals were grown by slow evaporation technique. Single crystal X-ray diffraction analysis reveals that the crystal lattice is monoclinic. From powder X-ray diffraction analysis the diffraction planes have been indexed. Fourier transform infrared spectrum for our sample confirms the presence of functional groups in the grown crystal. Second harmonic efficiency was determined using Kurtz powder method in comparison with urea to confirm the nonlinearity of the material. The results are discussed in detail.     

Effects of polarized excitation on the PJ manifolds emission in KYF4:Pr single crystal

A room temperature spectroscopic investigation on KYF₄:1.25 at%Pr³⁺ is presented. The effects on the optical properties of the multisite-disordered nature of the sample are studied and discussed. In particular we report on the broadening of the ³P_J absorption lines, at 10 and 300 K, and the 450–770 nm emissions as a function of observation and pump polarization. The evidence of a peculiar difference between emission under polarized excitation, parallel or orthogonal to the c axis, is shown. The ³P₀ lifetime was 45 μs in agreement with that measured in other fluoride hosts.     

Crystallization and characterization of nonlinear optical material l-arginine formomaleate

The influence of mixed acids in the growth and characteristic properties of a new nonlinear optical material l-arginine formomaleate abbreviated as LAFM was examined. Single crystal X-ray diffraction analysis was used to calculate the lattice parameters of the crystals. Fourier transform infrared (FTIR) spectroscopy and thermal analysis (DTA, TGA) were performed to study the molecular vibrations and thermal behaviour of the crystals. UV-VIS spectral study shows that LAFM is transparent down to 315 nm and its second harmonic generation efficiency is 1.2 times that of KDP.     

Synthesis,structural, topographical,linear and nonlinear optical,electrical and mechanical properties of Bisthiourea zinc acetate single crystal

Nonlinear optical material Bisthiourea Zinc Acetate (BTZA) was synthesized by slow evaporation solution growth technique. The grown crystals were characterised by Single crystal XRD and powder XRD studies. The presence of functional groups and the co-ordination of metal ions to Thiourea were confirmed by FTIR analysis. The UV-vis –NIR spectrum shows a low absorption in the entire visible and IR region. Optical band gap of the grown crystal was found to be 4.18 eV. The photoluminescence studies carried out and the crystal has blue emission. The Refractive Index was determined experimentally for the first time and found to be 1.508 for the incident wavelength of 632.8 nm. The second harmonic generation efficiency was determined using Kurtz and Perry powder technique and it was 0.7 times than that of the KDP crystal. Thermal properties were studied by thermo gravimetric analysis and differential thermal analysis. Dielectric studies were carried out at different frequencies for various temperatures. The mechanical behaviour of the grown crystal was studied using Vickers micro hardness tester. The growth mechanism and surface features are investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM).     

Crystal growth and frequency conversion of BaMgF4 single crystal by temperature gradient technique

The BaMgF₄ single crystal was grown by the temperature gradient technique. Highly pure MgF₂ and BaF₂ powders were used as raw materials and CaF₂ single crystal was chosen as a seed to induce BaMgF₄ single crystal grow along 〈0 0 1〉 orientation. The short cut-off wavelength of BaMgF₄ single crystal was determined to be 130 nm which is consistent with the previously reported result. We realized second harmonic generation from 1064 nm to 532 nm laser, and 800 nm to 400 nm femtosecond laser in single domain BaMgF₄ by using birefringent phase matching. 355-nm-wavelength laser was produced by Sum-Frequency Generation from 1064-nm- and 532-nm-wavelength laser, which is the shortest coherent radiation obtained in the UV in the BaMgF₄ crystal.     

Growth, structural, optical, thermal and mechanical properties of glycine zinc chloride single crystal

The nonlinear optical single crystals of glycine zinc chloride were grown by the slow cooling method from aqueous solution. The title compound was synthesized and purified by repeated recrystallization process. Grown crystals were characterized by X-ray diffraction, FT-IR and FT-Raman spectral analysis. The range and percentage of optical transmission were ascertained by recording UV-Vis-NIR spectrum. Thermal properties were investigated by DTA and TGA analyses. Its second harmonic generation relative efficiency was measured by Kurtz and Perry powder technique using Nd:YAG laser and was observed to be 0.5 times that of potassium dihydrogen orthophosphate. Its mechanical hardness was estimated by Vickers microhardness method.     

Wavelength dependence of Verdet constant of Pr doped terbium gallium garnet crystal

Samples of the magneto-active material – Pr³⁺: Tb₃Ga₅O₁₂ crystals with Pr³⁺ ion concentration of 1%, 2%, 3% and 5%. The Verdet constant measurement has been carried out at room temperature in the 400–1500 nm range for all crystal samples and was compared with a pure Tb₃Ga₅O₁₂ material. A high value of the Verdet constant for 5% Pr³⁺: Tb₃Ga₅O₁₂ crystal was obtained at room temperature – namely, 324.5, 200.1 and 68.7 rad/(T·m) for 532, 632.8 and 1064 nm, respectively. The Verdet constant of Pr doped TGG crystal at 1064 nm is much more higher than that of TGG. The superior performance of the materials indicates that Pr³⁺: Tb₃Ga₅O₁₂ crystals have great potential to meet the increasing demand for magneto-optical devices in the VIS-NIR wavelength.     

Structural, dielectric and optical properties of Ba(Ti, Zr)O3 thin films prepared by chemical solution deposition

Ba(Ti_0.95Zr_0.05)O₃ (BTZ) thin films grown on Pt/Ti/SiO₂/Si(100) substrates were prepared by chemical solution deposition. The structure and surface morphology of BTZ thin films has been studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). At 100 kHz, the dielectric constant and dissipation factor of the BTZ film are 121 and 0.016, respectively. The ellipsometric spectrum of the BTZ thin film annealed at 730 °C was measured in the range of wavelength from 355 to 1700 nm. Assuming a five-layer model (air/surface roughness layer/BTZ/interface layer/Pt) for the BTZ thin films on platinized silicon substrates, the optical constant spectra (refractive index n and the extinction coefficient k) of the BTZ thin films were obtained.