Organic Nonlinear Optical Crystal Research Articles

Growth Enhancement of Organic Nonlinear Optical Crystals by Femtosecond Laser Ablation

The impact of femtosecond (fs) laser ablation on the shape and nonlinear optical (NLO) properties of organic crystals was investigated. fs laser ablation of a local region of a NLO crystal can sele...

Synthesis, growth, optical studies and antimicrobial activity of a new semiorganic nonlinear optical crystal L-valine bariumchloride

A semi organic nonlinear optical single crystal of L-valine barium chloride was grown from an aqueous solution by the method of slow evaporation technique at room temperature. The grown crystal was characterized by powder X- ray diffraction confirms the presence of chloride. Single crystal X-ray diffraction studies confirm that the grown crystal belongs to the monoclinic system. The functional groups presented in the crystal were confirmed by FT-IR technique. The UV–vis-NIR spectrum indicates that the crystal has very good absorption in the entire visible and NIR region spectrum indicating the stability of the materials for NLO applications. The grown crystal was subjected to EDX to confirm the presence of the elements. The crystal was stable up to 260⁰C and fully decomposed at 907⁰C. Hence the thermal behaviour and the stability of crystal were studied by TGA, DTA and DSC. The second harmonic generation SHG efficiency was studied by Kurtz-Perry powder technique. The minimum inhibitory concentration (MIC) of the crystal for antibacterial activity was studied using micro dilution bioassay as described by ELOFF.

Ultra‐Broadband and High‐Dynamic‐Range THz Time‐Domain Spectroscopy System Based on Organic Crystal Emitter and Detector in Transmission and Reflection Geometry

The terahertz range of the electromagnetic spectrum reveals important insights when studying material properties. An ultra‐broadband terahertz time‐domain spectroscopy system based on state‐of‐the‐art, high‐stability organic nonlinear optical crystals used as both THz wave generator and detector is presented. In transmission geometry, a broad spectrum exceeding 20 THz and a high dynamic range of more than 80 dB is achieved using a compact 100 MHz femtosecond laser working at telecom wavelength 1560 nm. In the normal‐incidence reflection geometry, a similar bandwidth with a dynamic range surpassing 60 dB is reported. The experimental results are supported by a complete theoretical model, which includes the pump pulse duration, THz phonon/vibrational modes of the organic crystals and optical/THz beam path optimizations. The effectiveness of the newly developed system is demonstrated by measuring pharmaceutical samples with distinct THz features in the ultra‐broadband THz range and by measuring narrow water vapor lines at a spectral resolution of 2.7 GHz (0.090 cm−1), resulting in an excellent accuracy with a frequency deviation of less than 0.05% from the reference values.

Influence of metallic dopants on the growth, optical and mechanical properties of pure ammonium oxalate crystals

Abstract Ammonium Oxalate (AO), an organic nonlinear optical crystal was grown by slow evaporation solution growth technique. With an insight to explore the impact of impurities, metallic dopants (Cu+, Zn+ and Mn+) were added to pure AO and doped crystals were grown. FT - IR spectra were recorded for both pure and metal doped crystals of AO to identify the functional groups and confirm the inclusion of the dopants. The UV–Visible spectral studies were carried out for both pure and doped crystal to measure the absorbance and transmittance. The alteration in the optical band gap due to the inclusion of dopants were calculated and the obtained results supports the suitability of pure and doped materials in tuning optoelectronic devices. NLO studies were carried out on both pristine and doped crystals to measure the enhancement of the nonlinear properties due to the dopants added. Vickers hardness test was carried out on both pristine and doped AO to analyze the mechanical properties. Z-scan studies revealed that saturable absorption was exhibited by pure AO, Cu+ doped AO and Zn+ doped AO.

Experimental and theoretical investigations of organic creatininium 2-chloroacetate nonlinear optical single crystal

The main aim of this work is to synthesize creatininium 2-chloroacetate (CR2ClA) single crystal by using slow evaporation technique and to analyze its structural, optical and mechanical properties with the aid of experimental and theoretical techniques. The Single Crystal X-ray Diffraction analysis (SXRD) is carried out to identify the structural parameters. Hirshfield surface analysis explains the interactions present in the synthesized material. The optical property has been examined by using UV–visible spectral analysis and the optical constants such as band gap energy, extinction coefficient and refractive index were evaluated. HOMO–LUMO and MESP maps were successfully generated and analysed. The emission behavior was analysed by fluorescence spectral analysis. Third order optical non linearity was confirmed by Z scan analysis and the theoretical nonlinear optical parameters are calculated and analysed. The optical limiting behaviour and laser damage threshold analysis explains the synthesized materials laser assisting property. Mechanical property of the material has been analysed by Vicker’s microhardness analysis and the mechanical parameters such as yield strength and elastic stiffness illustrates the materials excellent atomic package.

Synthesis, crystal growth, and physicochemical characterization of 4-aminopyridinium 4-nitrophenolate 4-nitrophenol (4AP4NP) single crystals for NLO applications

The organic nonlinear optical (NLO) single crystal of 4-aminopyridinium 4-nitrophenolate 4-nitrophenol (4AP4NP) single crystal was grown by the solution method at room temperature. The unit cell parameters of the grown 4AP4NP single crystal were confirmed by single-crystal X-ray diffraction (SXRD) measurement. The various (hkl) planes of the grown crystal and their average lattice strain were analyzed by powder X-ray diffraction (PXRD). The crystalline perfection of the 4AP4NP single crystal was analyzed by high-resolution X-ray diffraction (HRXRD) measurement. The optical quality of 4AP4NP single crystal and its cut-off energy were analyzed by UV–Vis–NIR. The photoluminescence (PL) study reveals that the grown crystal has high-intense green emission at 500 nm. The thermal stability of the grown crystal was analyzed by TG/DTA. The mechanical stability was analyzed by Vickers microhardness measurement. The dislocation density of 4AP4NP crystal has been investigated by etching studies. Laser-induced damage threshold (LDT) of the 4AP4NP crystal was analyzed by Q-switched Nd:YAG laser of wavelength 532 nm. The optical homogeneity of 4AP4NP was determined by the birefringence interferometry technique. The dielectric measurement has been carried on the grown crystal. The electronic polarizability (α*) of the grown crystal was determined by various theoretical calculations. The second-harmonic generation (SHG) and third-order nonlinear optical properties of the grown 4AP4NP crystal were analyzed by Kurtz–Perry powder and Z-scan technique, respectively.

Chemical growth dynamics of 4-Methyl-4′-Hydroxy Benzylidene Aniline NLO single crystal structure and spectroscopic applications

An aromatic Schiff bases organic nonlinear optical single crystal of 4-methyl-4′-hydroxy benzylidene aniline (MHBA) was grown by slow evaporation solution growth technique and the solubility of MHBA in ethanol at increasing temperature was esteemed. The unit cell proportions were gained by both single crystal and powder X-ray diffraction analysis. The structural refinement of MHBA shows that it crystallizes in the orthorhombic system with space group Pbcn. The molecule chiefly consists of two non – planar benzene rings attached by carbon and nitrogen atoms. The various planes of reflection were identified from the powder X-ray diffraction study and the unit cell proportions were same for single crystal XRD. Functional assemblies were entrenched by using Fourier transform infrared and FT Raman analysis by the molecular vibrations in the MHBA crystal. The assignment of protons and carbons in the grown MHBA crystals were recognized from 1H and 13C Nuclear Magnetic Resonance Spectroscopy analyses. The UV- visible and fluorescence spectral evaluate were carried out and to find the optical transmission and emission range of MHBA. The second harmonic generation productivity of MHBA is about 1.04 times than that of a standard sample of potassium dihydrogen orthophosphate. The thermal constancy of the grown crystal was investigated by differential scanning calorimetric, thermo gravimetric and a differential thermal analysis which confirms the decomposition of the sample occurs at 120 °C. Mechanical stuff, the hardness number, yield strength and Young's modulus of the grown material were studied using Vickers micro hardness tester and the work hardening coefficient reveals that MHBA belongs to the family of soft materials. The dielectric measurements with frequency and temperatures were used to find the power dissipation of the grown MHBA crystals.

Synthesis and crystal growth of 2, 3-dimethyl-N-[2-(hydroxy) benzylidene] aniline: An organic second-order non-linear optical crystal for non-linear optical (NLO) applications

Abstract Optically transparent organic single crystal of 2,3-Dimethyl-N-[2-(hydroxy) benzylidene] aniline (DHBA) has been successfully prepared, and the single crystals were grown with dimensions up to 10 × 5 × 2 mm3 by using slow evaporation solution growth method in methanol. Single crystal X-ray diffraction (SCXRD) study revealed that the DHBA was crystallized in an orthorhombic crystal structure with P212121 space group, which is a crucial parameter for the second harmonic generation. The existence of various functional groups in the DHBA molecular structure was characterized by FT-IR, FT-Raman, and 1H NMR techniques. UV–Vis–NIR absorption study reveals that the lower cut-off wavelength at 464 nm with transparency over the Vis-NIR spectral regions. The photoluminescence (PL) spectra of DHBA crystal exhibit a green emission centered at 538 nm. The thermal stability and melting temperature of DHBA was assessed by TG/DTA analysis. Vickers microhardness studies have also been investigated to check the mechanical stability of the grown crystal. The dielectric properties of DHBA have been tested in various frequency ranges from 50Hz to 5 MHz at three different temperatures (308K, 323K, and 348K), and the results are discussed. The second order NLO efficiency of the powdered DHBA crystal is three times greater than that of KDP. All of these results imply that DHBA crystal could be a desirable candidate for non-linear optical applications.

Growth and characterization of pure and metals-doped organic nonlinear optical single crystal: l-alanine alaninium nitrate (LAAN)

The pure and metal ion (Cu2+, Zn2+ and Mg2+)-doped LAAN single crystal was developed by slow evaporation technique under ambient temperature. Cell parameters of the grown crystal were identified using single crystal X-ray diffraction analysis and found that the material crystallizes in orthorhombic crystal system with space group of P21.The presence of functional groups and the spectral properties were assessed by FTIR analysis. Transmittance spectrum reveals that the crystal has a low UV cut-off of 360 nm and has a good transmittance in the entire visible region. The band gap energy of LAAN and doped (Zn, Cu and Mg) LAAN crystals were estimated to be 3.38, 3.22, 2.75, and 3.13 eV by Tauc plot. Prevention of the recombination process of electron–hole pair was also confirmed by photoluminescence spectra analysis. The dielectric constant of pure crystal was found to be less than that of doped crystals. The AC conductivity was found to increase after doping and with the increase in temperature. Second harmonic generation efficiency of the grown crystal has been measured by Kurtz and Perry technique and it was found that Cu-doped LAAN is 3.2 times higher than that of KDP and 2.1, 1.5, and 1.8 times more prominent than pure, Zn, and Mg-doped LAAN crystals, respectively.

Growth of High-Quality DSTMS Single Crystals with Enhanced Optical Properties for Photonic Applications

Highly efficient organic nonlinear optical stilbazolium crystals of 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS) single crystal were grown by slow solvent evaporation technique using methanol as a solvent. The structure and cell parameters of the grown crystals were derived from single crystal and powder x-ray diffraction analyses, and the optical properties of the grown crystal were analyzed by a UV–Vis spectrophotometer. The band gap of the grown crystal was found to be 2.28 eV. The vibrating modes of functional groups in the grown crystal were identified by FTIR spectroscopy. The dielectric measurement was made as a function of frequency (1 Hz–1 MHz) at different temperatures (50–200°C) in steps of 50°C. The dielectric constant and dielectric loss were found to be strongly dependent on temperature and frequency of the applied electric field. The semicircle in the Cole–Cole plot showed the presence of dielectric relaxation in the crystal with its radius representing the resistance of the crystal. The resistivity and AC conductivity were calculated from the measured dielectric data.

Terahertz wave up-conversion detection based on organic nonlinear optical crystals

Laser pumped terahertz (THz) wave up-conversion detection with high sensitivity, fast responsivity and wide frequency band is achieved at room temperature, based on home-made organic nonlinear crystals 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST). Green laser pulses pumped KTiOPO<sub>4</sub> optical parametric oscillators are utilized as the sources of dual-wavelength near-infrared (NIR) beams (1.3–1.6 μm, for THz-wave difference frequency generation (DFG)) and a single NIR beam (1.2–1.4 μm, for up-conversion detection). The nonlinear medium for both THz-DFG and detection is DAST (grown by CETC-46). A nanosecond-time-resolved THz pulse is obtained with an InGaAs p-i-n photo-diode. The spectrum of the up-converted NIR light is acquired, which allows us to measure the THz frequency indirectly. The sensitivity (also at room temperature) is 4 orders better at 19 THz than the sensitivity of a commercial thermal detector (Golay Cell). The wide frequency band operation is realized with different sets of band-pass filters, which cover the entire range from 3.15 to 29.82 THz except 8.4 THz of the strong absorption peak of DAST. The dynamic range of a THz source based on DFG can be commonly improved by 2–3 orders, by changing the traditional thermal detector with the up-conversion detection. The presented technology can promote the applications of DFG THz source in the fields of high-resolution spectroscopy and imaging.

The exploration of the crystal nucleation parameters and physico-chemical analysis of a single crystal: 2-amino-4,6-dimethoxypyrimidinium hydrogen (2R,3R)-tartrate 2-amino-4,6-dimethoxypyrimidine.

This paper discusses the structural orientations and the physico-chemical properties of a single crystal of 2-amino-4,6-dimethoxypyrimidinium hydrogen (2R,3R)-tartrate 2-amino-4,6-dimethoxypyrimidine (2ADT). The experimental investigation of the properties of the compound improves the potential for the utilization of the crystalline compound in the fabrication of optical limiting and nonlinear optical devices. For the growth process, an organic nonlinear optical crystal of 2ADT is synthesized conventionally at varying molar concentrations to achieve an excellent yield. The structural orientations and refinements of the compound are identified and discussed with reference to a single crystal X-ray diffraction study and its supporting computations. The results of the experimental analysis via UV-vis-NIR spectrometry and a z-scan setup with a laser beam source are used in an in-depth discussion on the linear and nonlinear optical properties of the crystal together with its damage threshold induced by a Nd:YAG laser beam at 1064 nm. With optical transparency of 55% in the entire visible region, a lower cut-off wavelength at 228 nm, and a bandgap at 5.2 eV, the crystal was demonstrated to be suitable for use in optical device fabrication. The thermogravimetrically assessed thermal stability of 2ADT was examined up to 147 °C. In addition, the thermodynamic parameters responsible for activation reactions are also discussed because these give information about the material's thermal behavior. An optical limiting study revealed that the transmitted output power increases linearly with the input power at about 1.89 mW cm−2.

Linear–nonlinear optical and quantum chemical studies on Quinolinium 3,5-dinitrobenzoate: A novel third order non-linear optical material for optoelectronic applications

An organic non-linear optical (NLO) crystal of Quinolinium 3,5-dinitrobenzoate (DNBAQ) was synthesized and good quality single crystals of DNBAQ were grown by conventional slow evaporation solution growth technique. Single crystal XRD was utilized to confirm the formation of the charge transfer complex. The crystalline property and the presence of required functional groups was verified employing Powder XRD and FTIR spectral analysis. UV–Vis–NIR and Fluorescence study was performed to determine the optical transmittance and the emission property of the grown crystal. The thermal, mechanical and surface damage threshold stability of the complex was analysed using thermal studies, Vicker’s micro hardness studies and Laser damage threshold measurement. The solid state parameter of electronic polarizability of DNBAQ compound was computed through dielectric studies. The non-linear optical characterizations like Kurtz Perry powder technique and Z-Scan technique ensures the non-linear optical activity of the compound. The frequency conversion efficiency of the grown crystal was estimated to be 70% that of the standard Potassium Dihydrogen Phosphate (KDP). Z-Scan analysis confirms the suitability of the grown crystal for optical limiting and switching applications. Quantum chemical studies were adopted on the optimized geometry of DNBAQ molecule using Density Functional Theory (DFT). Frontier Molecular Orbital (FMO) analysis and Molecular Electrostatic Potential (MEP) analysis were performed. The non-linear optical behaviour of the complex was established by evaluating dipole moment, polarizability and hyperpolarizability features. All the above results confirm the resourceful candidature of DNBAQ material for optoelectronic and photonic applications.

Solid‐State Molecular Motions in Organic THz Generators

AbstractOrganic nonlinear optical salt crystals are widely used as efficient broadband THz generators. Although solid state molecular motions of organic crystals can greatly influence THz generation characteristics, their origin and effects on THz photonics are not clearly identified. In this work, the origin of solid‐state molecular motions of the state‐of‐the‐art nonlinear optical organic salt crystals and their effects on THz generation characteristics are theoretically investigated. A model crystal, HMQ‐TMS (2‐(4‐hydroxy‐3‐methoxystyryl)‐1‐methylquinolinium 2,4,6‐trimethylbenzenesulfonate) with large macroscopic optical nonlinearity, which is very attractive for intense broadband and narrowband THz wave generation, is chosen. The solid‐state molecular vibrations of HMQ‐TMS crystals can be classified in three frequency regions: phonon mode region, intramolecular motion region, and their mixing region. For the first time for ionic organic crystalline THz generators, the contributions of cationic chromophores and anionic matchmakers on each of vibrational modes are quantitatively separated. In addition, the influence of solid‐state molecular vibrations of HMQ‐TMS crystals on the generated THz spectra is investigated. These results provide an essential information for design of new organic nonlinear optical salt crystals for THz generators as well as detectors and for optimization of THz generation performance.

Crystal growth, structural, optical and theoretical investigations of organic nonlinear optical crystal: 2-naphthalenol

A good quality organic NLO single crystal of 2-Naphthalenol (2 N) are grown by slow solvent evaporation method. The grown 2 N crystal is analyzed with different characteristic studies such as single crystal XRD, UV, spectroscopic, and NLO. The grown 2 N crystal has above 80% of transmission throughout the visible and IR region. The HOMO–LUMO energy values and the molecular electrostatic potential and the polarizability properties of 2 N crystal are analyzed from DFT theory. The laser damage threshold value has been assessed using Nd:YAG laser as source. The 2 N crystal acquires 2.7 times higher SHG proficiency compared with KDP material.

Crystal growth and characterization of 2-(4-(dimethylamino) styryl)-benzothiazole: A potential organic nonlinear optical crystal

Abstract Research progress of an organic second-order nonlinear optical crystal 2-(4-(dimethylamino)styryl)-benzothiazole (DMASBT) was grown with slow cooling method and its performance characterization in different aspects were reported. It was found that the crystals had a high second harmonic generation efficiency of 9.8 times higher than that of KDP crystal. Crystal structure of the crystal was investigated by single crystal XRD. It was found that the crystal lattice is monoclinic. In addition, the crystal growth mechanism and intermolecular interaction were analyzed by chemical etching and Hirshfeld surface. The functional groups of the raw materials were determined by FT-IR, Raman, 1H NMR and elemental analysis. UV–vis–NIR spectrum, dielectric properties under different frequencies, thermal stability, and photostability of the crystal in powder state were also studied.

Investigation on structural, optical, mechanical, thermal and nonlinear optical activity of 2-methylazinium (2,4,6)-trinitrophenolate – experimental and DFT approach

Organic nonlinear optical single crystal of 2-methylazinium (2,4,6)-trinitrophenolate (2MATNP) was grown by slow evaporation technique at room temperature. The structural parameters were analyzed by single crystal x-ray diffraction analysis which reveals that the 2MATNP crystallizes in triclinic crystal system with P1¯ space group. The intermolecular interactions present in the 2MATNP were pictorially explained by using Hirshfeld surface analysis. The functional groups present in the synthesized crystal lattice were analysed with FTIR and FT-Raman spectral studies. The transmittance ability of the grown 2MATNP was studied by using UV-visible transmittance spectral analysis and the optical band gap was evaluated. NBO analysis confirms the hydrogen bonding and hyperconjugative interactions whereas the nature of atomic charges was explained by Natural Population analysis. The global reactivity descriptors and the intermolecular charge transfer interactions were analyzed by using HOMO-LUMO and MESP analysis. Nonlinear optical property was studied experimentally and theoretically which indicates the effective nonlinear optical efficiency of grown 2MATNP single crystal. The mechanical stability of the grown 2MATNP was analyzed by using Vicker's microhardness test. Thermal behavior has been analysed by TG/DTA analysis.

Experimental and Theoretical Studies on Various Linear and Non-linear Optical Properties of 3-Aminopyridinium 3,5-Dinitrobenzoate for Photonic Applications

3-Aminopyridinium 3,5-dinitrobenzoate (APDNBA), an organic non-linear optical crystal was synthesised and grown from slow evaporation solution growth technique. Single-crystal XRD and powder XRD were performed to identify and confirm the crystalline nature of the grown crystal. Various characterizations like UV-Vis-NIR studies and fluorescence studies were conducted to determine the optical transparency and emission property of the APDNBA crystal. FTIR analysis was carried out to confirm the formation of the charge-transfer complex. The overall stability of the compound was verified employing thermal, mechanical and laser damage threshold studies. Dielectric measurement was utilised to evaluate the electronic polarisability character of the grown crystal. Non-linear optical activity of the grown crystal was analysed through Kurtz-Perry powder technique and Z-scan studies. The optical limiting and switching applications of the compound were confirmed by the non-linear studies. Additionally, quantum chemistry calculations were carried out to predict the chemical stability, chemical reactivity, and non-linear character of the APDNBA molecule. The formulations was done based on density functional theory (DFT) with the Gaussian09 suite, using B3LYP functional of 6-31++G*(d,p) level of theory. Based on the obtained results, the grown crystal of APDNBA could be recommended as a resourceful non-linear optical candidate for opto-electronic and photonic applications.

Synthesis, crystal growth, spectroscopic characterization and DFT studies of 4-(E)-1-(4-chlorophenyl)-3-(4-nitrophenyl)prop-2-en-1-one (CPNP) single crystal as a nonlinear optical (NLO) material

Abstract An organic nonlinear optical single crystal of 4-(E)-1-(4-chlorophenyl)-3-(4-nitrophenyl) prop-2-en-1-one [CPNP] was synthesized and its single crystal grown by solution growth technique. XRD analysis of the CPNP single crystal confirms that the crystal belongs to orthorhombic system with non centrosymmetric space group Pna21. The characteristic functional groups in the crystal were identified by FT-IR analysis. The CPNP crystal exhibits an optical transparency of 76% with optical band gap energy of 2.88eV. The HOMO-LUMO energy gap calculated from DFT for a single-molecule in the gas phase was found to be 3.88 eV. The thermal stability of the CPNP crystal was analyzed by TGA/DSC analysis. The CPNP crystal exhibits photoluminescence property with strong emission at 615nm in the orange red region. The LDT value of the CPNP crystal was found to be 1.72 GW/cm2. The SHG efficiency of CPNP crystal is 0.75 times greater than that of standard urea.

Crystal growth, structural, optical and piezoelectric investigations on novel B4AAT (bis-4-acetylanilinium tartrate): A phase matchable second and third-order NLO single crystal for optoelectronic and nonlinear optical device applications

Abstract A novel organic nonlinear optical crystal, bis (4-acetylanilinium) tartrate (B4AAT) has been synthesized and successfully grown by a slow evaporation method using acetone as a solvent at ambient temperature. The single-crystal X-ray diffraction study reveals that B4AAT crystallized into a triclinic system with the noncentrosymmetric space group (P1). The crystalline perfection of the grown crystal was affirmed by the High-resolution XRD study. The characteristic functional groups with vibrational assignments and molecular structure of B4AAT were confirmed through Infrared, Raman and NMR spectroscopic analyses. UV–Vis–NIR spectral analysis of the crystal shows 69% of transmittance with a lower cut-off wavelength at 334 nm. The grown crystal was thermally stable up to 143.39 °C. The laser-induced damage threshold of the B4AAT compound was found to be 15.78 GW/cm2 for 1064 nm Nd: YAG laser radiation. The grown B4AAT possesses the low value of dielectric constant and piezoelectric charge coefficient (d33 = 5.86 pC/N) for the supercapacitor and microelectronics industry. The size-dependent of second harmonic generation efficiency of the crystal was found to be 4.6 times higher than that of KDP. The photoluminescence and lifetime measurements of the molecules in the crystal were studied by Fluorescence spectral analysis. The third-order nonlinear optical activity estimated utilizing the Z-scan method reveals that the B4AAT possesses saturable absorption, negative nonlinearity with self-defocusing and optical limiting effect. The aforesaid results confirm that B4AAT crystal is a potential candidate for optoelectronic and nonlinear optical device applications.