Inorganic Nonlinear Optical Crystals Research Articles

Machine Learning with Multilevel Descriptors for Screening of Inorganic Nonlinear Optical Crystals

Nonlinear optical (NLO) crystals are the key materials in modern laser technology and science because of their intrinsic capability to convert the wavelength of the light source. The search for new...

Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV–Vis–NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz–Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

Novel report on SHG efficiency, Z-scan, laser damage threshold, photoluminescence, dielectric and surface microscopic studies of hybrid inorganic ammonium zinc sulphate hydrate single crystal

Hybrid inorganic nonlinear optical crystals find huge applications in laser assisted photonic devices therefore present communication firstly aims to investigate the dielectric, microscopic and linear-nonlinear optical properties of ammonium zinc sulphate hydrate (AZSH) crystal. The inorganic AZSH complex has been synthesized and 15 × 10 × 09 mm3 single crystal was grown by slow solvent evaporation method. The powder and single crystal X-ray diffraction technique has been employed to evaluate the crystalline phase and determine the structural parameters of AZSH crystal. The optical transparency of AZSH crystal has been examined within the wavelength rage of 200–1100 nm. The enhanced second harmonic generation efficiency of AZSH crystal is 2.53 times higher than standard KDP crystal. The laser damage threshold of AZSH crystal has been determined using the Nd:YAG laser operating at 1064 nm. The close and open aperture Z-scan studies have been performed to ascertain the nature of third order nonlinear optical (TONLO) refraction and absorption of AZSH crystal. The order of TONLO parameters n2, β and χ3 is found to be 10−9 cm2/W, 10−4 cm/W, 10−4 esu respectively. The AZSH crystal is found to have violet colored luminescence emission centered at 370 nm. The dielectric constant and dielectric loss of AZSH crystal has been evaluated within 30 Hz to 1 MHz. The chemical etching technique has been imposed to examine the growth habitat and determine the etch pit density of AZSH crystal.

Crystal growth and characterization of an efficient semi-organic nonlinear optical (NLO) donor-π-acceptor single crystal: 2-amino-5-nitropyridinium nitrate (2A5NPN) grown by slow evaporation solution technique (SEST)

The semi-organic nonlinear optical 2-amino-5-nitropyridinium nitrate (2A5NPN) single crystals were successfully grown by slow evaporation solution technique with the dimension of 10 × 10 × 10 mm3. The crystalline structure of 2A5NPN was confirmed by single crystal X-ray diffraction measurement. The optical quality of the grown crystal was studied using UV–Vis–NIR spectrum analysis. It shows that the grown crystal has 69% of transmittance with the lower cut-off wavelength of 404 nm. The refractive index of 2A5NPN single crystal was calculated using the Prism-coupling method. The thermal diffusivity was analyzed using photoacoustic measurement. The dark and photoconductivity of the grown crystal were analyzed and the result shows that the crystal has negative photoconductivity nature. The mechanical strength of 2A5NPN crystal was analyzed by Vickers microhardness tester and the hardness number ( $${H_v}$$ ), Meyer’s index (n), yield strength (σy), stiffness constant (C11) and Hays–Kendall relation were evaluated. The fundamental solid state parameters such as valence electron plasma energy (ћωp), Penn gap (Ep), Fermi energy (Ef) and various type of electronic polarizability (α) of the grown crystal were determined using the dielectric parameters. The HOMO–LUMO energy and first-order hyperpolarizability (β) of 2A5NPN molecule were calculated in the gas phase by density functional theory. The laser damage threshold measurement has been performed and it reveals that the optical damage tolerance power of the grown crystal is high compared to other organic and inorganic NLO crystals. The third-order nonlinearity of 2A5NPN was assessed using an open and closed aperture Z-scan technique. The above results show that 2A5NPN crystal is a potential candidate for nonlinear optical device applications.

Investigation on the crystal growth, molecular structure and nonlinear optical susceptibilities of 2-[2-(4-Ethoxy-phenyl)-vinyl]-1-ethyl-stilbazolium iodide (EESI) by Z-scan technique using He–Ne laser for third-order nonlinear optical applications

Organic 2-[2-(4-Ethoxy-phenyl)-vinyl]-1-ethyl-stilbazolium iodide (EESI), a derivative of the stilbazolium family single crystal was synthesized by condensation method. Nearly perfect as-gown single crystals of EESI structure was confirmed by single-crystal X-ray diffraction studies. The crystal has a triclinic system with the space group P-1, the molecule consists of one pyridinium cation, one iodide anion, and 0·5H2O molecules. The nature of charge transfer, molecular properties, electrostatic potential map, and HOMO-LUMO energy gap of EESI have been theoretically investigated by Sparton’10 V1.0.1 program. The optical transparency of EESI was studied by Uv–Visible spectral analysis. The growth features were observed during the etching studies using a Carl Zeiss optical microscope (50X magnification). The mechanical behavior of the crystal was estimated by Vickers microhardness test, which shows reverse indentation size effect (RISE) with good mechanical stability. Both the dielectric constant and dielectric loss increases with the increasing temperature and attain almost constant at higher frequencies, which justify the crystal quality and essential parameter for electro-optic device applications. The complex impedance analysis explains the electrical property of EESI. TGA and DTA measurements determined the thermal stability of the grown crystal. Laser-induced damage threshold energy measurements exhibit that the excellent resistance with good threshold energy up to 2.08GW/cm2 that was found to be more than that of some known organic and inorganic NLO crystals. Photoconductivity of EESI crystal confirms that the positive photoconductivity nature. Also, the third-order nonlinear optical (NLO) properties of EESI were investigated by using the single beam Z-scan technique under the Visible light (632.8nm) region. The results show that EESI has effective third-order nonlinear optical property with the nonlinear refractive index n2 =1.787×10-11m2/W, third-order nonlinear optical susceptibility χ(3) =4.229×10-6esu and second-order hyperpolarizability (γ) =1.468×10–33 esu. It is found to be larger than that of some organic NLO materials. All the obtained results are making it a potential candidate as useful non-linear optical (NLO) applications.

Synthesis, growth, and structural, optical, mechanical, electrical properties of a new inorganic nonlinear optical crystal: Sodium manganese tetrachloride (SMTC)

A new inorganic nonlinear optical single crystal of sodium manganese tetrachloride (SMTC) has been successfully grown from aqueous solution using the slow evaporation technique at room temperature. The crystals obtained using the aforementioned method were characterized using different techniques. The crystalline nature of the as-grown crystal of SMTC was analyzed using powder X-ray diffraction. Single-crystal X-ray diffraction revealed that the crystal belongs to an orthorhombic system with non-centrosymmetric space group Pbam. The optical transmission study of the SMTC crystal revealed high transmittance in the entire UV–vis region, and the lower cut-off wavelength was determined to be 240nm. The mechanical strength of the as-grown crystal was estimated using the Vickers microhardness test. The second harmonic generation (SHG) efficiency of the crystal was measured using Kurtz's powder technique, which indicated that the crystal has a nonlinear optical (NLO) efficiency that is 1.32 times greater than that of KDP. The dielectric constant and dielectric loss of the compound were measured at different temperatures with varying frequencies. The photoconductivity study confirmed that the title compound possesses a negative photoconducting nature. The growth mechanism and surface features of the as-grown crystals were investigated using chemical etching analysis.

Computational design of inorganic nonlinear optical crystals based on a genetic algorithm

A theoretical method to design inorganic nonlinear optical crystals for second harmonic generation (SHG) is presented here.

ChemInform Abstract: Synthesis and Characterization of Borate Based and AgGaS2 Materials

AbstractReview: 12 refs.

Second-harmonic generation spectroscopy on organic nanofibers

Optical second-harmonic generation upon nanosecond laser irradiation of nanofibers grown from nonsymmetrically functionalized para-quarter-phenylene molecules on mica surfaces is investigated in the spectral region around electronic resonances. Strong multiphoton excited luminescence appears together with the second-harmonic signal in the spectra. It is demonstrated how the two components can be separated by analyzing emission spectra recorded over a broad range of wavelengths around the second-harmonic energy. Spectra of the absolute values of the second-harmonic signals are obtained for three differently functionalized molecules. Together with supplementary measurements of the structure of the nanofiber films this forms the basis for estimation of the second-harmonic susceptibility of the fiber materials. Values of the nonlinear susceptibilities are obtained, which are comparable to those of well-known inorganic nonlinear optical crystals.

Synthesis and characterization of borate based and AgGaS2 materials

In recent years, there has been tremendous development in the fabrication of suitable materials for optoelectronic, laser, photovoltaic devices, acousto-optic, sonar and infrared detectors applications. Mastering in synthesis, growth and characterization is an essential requirement for fully realizing the potential applications of the materials technology for the construction of novel devices for Laser, microwave, optoelectronic and other applications. The anisotropy in the crystals gives them enhanced properties as required in the field of non-linear optics. With the advent of laser sources, a nonlinear optical phenomenon has got tremendous interest and nonlinear optical (NLO) materials play a key role in the development of laser technology. Because of the variety and complexity of the material systems involved, several approaches towards synthesis, growth and characterization have been developed during the past decades. Laser materials can be classified into Inorganic, Organic and Semi organic categories. Urea, DAST, mNA, POM, NPP, MAP are examples of organic family crystals where as L-Arginine phosphate (LAP), Zinc tris thiourea sulphate (ZTS), BTCC, ZCTC belongs to semi organic class. Inorganic NLO crystals are Potassium titanyl phosphate (KTP), GdYCOB, KAB, Beta Barium Borate (BBO), LBO, KDP and LiNbO3. Synthesis and characterization of technologically important Borate based materials for NLO applications will be reviewed. The raising demand for UV lasers has led to the development of various NLO materials. A series of borate materials – Rare earth calcium oxy borate (RECOB) with the general chemical formula RECa4O(BO3)3 with RE=Y,Gd, Nd, Sm, etc. are reported to be synthesized from their repective melts. The RECOB crystals are excellent NLO materials and when doped with `laser-active' ions (Nd3+, Yb3+), they become efficient laser-host crystals. The single crystals of YCOB were grown by flux technique using boron-tri-oxide as a flux. This technique enables to grow YCOB crystals below its melting point (1510°C) . Powder XRD studies were carried out on both the polycrystalline and single crystals of YCOB using the CuKα X-rays (λ = 540 Å) at a scan rate of 0.05°/ min. The formation of YCOB was confirmed in both the samples. The powder XRD pattern of the grown crystals reveals the formation pure YCOB single phase. There are no excess peaks due to impurities or flux incorporations. UV-VIS-NIR studies were carried out on the as-grown crystals of YCOB which indicates that YCOB crystals have a sharp cut-off around 220 nm and the crystal is highly transparent (>75%) from 220 – 1100 nm. The high transparent nature of the crystals from the deep UV region enables it to be an excellent NLO material for UV applications. The results obtained suggest that flux technique is an excellent method to grow YCOB crystals. Crystal growth and characterization of novel borate materials like XAl3(BO3)4 where X = Nd, Yb and Er will be reviewed in detail.

Effect of hydrogen bonds on optical nonlinearities of inorganic crystals

This work probes the role of hydrogen bonds (such as O–H⋯O and N–H⋯O) in some inorganic nonlinear optical (NLO) crystals, such as HIO 3, NH 4H 2PO 4 (ADP), K[B 5O 6(OH) 4]·2H 2O (KB 5) and K 2La(NO 3) 5·2H 2O (KLN), from the chemical bond standpoint. Second order NLO behaviors of these four typical inorganic crystals have been quantitatively studied, results show hydrogen bonds play a very important role in NLO contributions to the total nonlinearity. Conclusions derived here concerning the effect of hydrogen bonds on optical nonlinearities of inorganic crystals have important implications with regard to the utilization of hydrogen bonds in the structural design of inorganic NLO crystals.

Nonlinearity of the complex crystals with O-H bond

A systematic and quantitative research on the structure-property correlation has been carried out in KH2PO4 (KDP), NH4H2PO4 (ADP) and HIO3, based on the dielectric theory of complex crystals and the Levine bond charge model. We, for the first time, successfully solve the problems in the calculation of the nonlinearities of the complex inorganic nonlinear optical (NLO) crystals, which have OH bonds in their crystal structures. We do this by introducing the bond-valence equation we have set up, calculating the nonlinear optical tensor coefficients dijk of these three compounds, quantitatively determining the contributions of each type of bond to the total second-order NLO tensor coefficient (dijk) of the crystal, and presenting the bond parameters and the linear properties of each kind of bond. For the first time, the NLO coefficient d36 for ADP was calculated. All calculated results are in good agreement with experimental data. We found that OH bonds also play an important role in these crystals, except for in the important anionic groups (PO4 groups and IO3 groups). All the results thus calculated show that our method is useful in evaluating the NLO coefficients of the inorganic NLO crystals containing OH bonds in their structures, and should be a useful tool toward the future research into new nonlinear optical materials of this kind.

無機非線形光学結晶

無機非線形光学結晶

Design and synthesis of an ultraviolet-transparent nonlinear optical crystal Sr2Be2B2O7

POWERFUL, tunable ultraviolet laser sources, required for many spectroscopic applications, rely on the frequency-doubling of lasers in the visible range. Such second-harmonic generation (SHG) depends on the development of nonlinear optical (NLO) materials with high SHG coefficients, a wide transparent region in the ultraviolet, and moderate birefringence. Few such materials are available; those most widely used at present are the inorganic crystals β-BaB2O4 (BBO)1 and LiB3O5 (LBO)2. These crystals are effective for SHG only down to wavelengths of 205 nm (ref. 3), because of a limited ultraviolet-transparent range in the former case and birefringence problems in the latter. We have developed previously4 a new inorganic NLO crystal, KBe2BO3F2 (KBBF), which avoids both of these problems to a large degree. But it is hard to grow large crystals of KBBF because of weak binding between its layered structural units. We have now developed an improved material by rational design: Sr2Be2B2O7 (SBBO), which shares (and in fact slightly improves on) all of the favourable NLO properties of KBBF and is easy to grow as large (so far up to 7 × 7 × 3 mm) crystals of high optical quality. The large SHG coefficients and wide range of ultraviolet transparency make this material a promising candidate for frequency doubling into the ultraviolet.

Structure of bis(2-amino-5-nitropyridinium) dichromate as a step towards the design of efficient organic–inorganic non-linear optical crystals

The orthorhombic crystal structure of 2C 5 H 6 N 3 O 2 + .- Cr 2 O 7 2- (a=22.454 (6), b=15.129 (2), c=5.189 (2) A, Z=4, orthorhombic, P2 1 nb, D x =1.866 g cm -3 ] has been solved using direct methods and refined to wR=0.029 for 2514 reflections. This study provides a step towards a new route to obtain non-linear optical crystals which aims at combining the highly polarizable 2-amino-5-nitropyridinium cation with inorganic anionic host matrices. The shielding effect of dichromate anions in the building of an acentric polar framework is discussed

Quadratic nonlinear-optical properties of a new transparent and highly efficient organic–inorganic crystal: 2-amino-5-nitropyridinium-dihydrogen phosphate (2A5NPDP)

Linear and quadratic nonlinear-optical (NLO) properties of a new organic–inorganic crystal, 2-amino-5-nitro-pyridinium-dihydrogen phosphate (2A5NPDP), are reported. 2A5NPDP was designed to display high NLO efficiency by incorporating highly polarizable organic molecules arranged in a polar order between phosphate polyanion sheets. The material is transparent in the visible and the near-IR (from 0.42 to 2 μm) with favorable phase-matching (PM) conditions for second-harmonic generation in the 1-μm region. Crystal nonlinear coefficients responsible for PM were determined by the Maker fringe method, leading at 1.06 μm to d15 ≅ 7.2 pm/V and d24 ≅ 1.3 pm/V. The measured crystal coefficients significantly depart from oriented gas model calculations based on molecular hyperpolarizability values measured in an aprotic solution, thus suggesting important crystal-field effects and protonation contributions. Thermal sensitivity of the PM angle at 1.34 μm is found to be 155″/°C, which is considerably larger than typical values of inorganic NLO crystals and opens the way to efficient thermal tuning of phase-matched processes.

Absorption-edge calculations of inorganic nonlinear optical crystals

A theoretical model suitable for calculating absorption edges of inorganic nonlinear optical (NLO) crystals is introduced. This model is proved to be useful to elucidate the relationship between electronic structures of NLO-active groups and macroscopic properties of absorption edges on the UV side of most of the inorganic nonlinear optical crystals. A systematic calculation of absorption edges on the UV side for several important inorganic NLO crystals is carried out by means of DV-SCM-Xα method and all calculated results are in good agreement with experimental data. These inorganic NLO crystals include LiB3O5(LBO), β-BaB2O4(BBO), KB5, KDP, Na2SbF5, Ba2TiSi2O8, iodate and NaNO2. The calculated energy level structures of LiB3O5 and β-BaB2O4 crystals are compared with the measured XPS spectra. The unusual transparent spectra of KB5 and KDP crystals are partly explained from the microstructure point of view. The effect of lone electron pair in iodate and NaNO2 crystals on their absorption edges are discussed. All these results show that Anionic Group Theory of Nonlinear Optical Crystals is useful to evaluate the absorption edges of the inorganic nonlinear optical crystal and is a powerful tool in a Molecular Engineering approach to search for new nonlinear optical materials.