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Crystal growth and optical characterization of an organic single crystal for frequency conversion applications
摘要： Organic nonlinear optical 2-methylquinolinium L-malate single crystals have been grown by slow evaporation solution growth technique from a mixture of 2-methylqiunoline and L-malic acid in ethanol solution at ambient temperature. Single crystal X-ray diffraction analysis reveals that grown crystal in monoclinic system with non-centrosymmetric space group P21 and the lattice parameters are a = 7.35 ?, b = 26.51 ?, c =10.83 ?, α = γ = 90o, β = 102.95o and V = 2057.4 ?3. UV-vis spectrum indicates that the crystal is transparent (75%) in the entire visible region with a cut-off wavelength of 437 nm and optical energy band gap Eg is found to be 2.71 eV. Microhardness measurement reveals the mechanical strength of the grown crystal. The photoluminescence spectrum shows the blue emission of the crystal. Laser damage threshold studies was carried out to ascertain the suitability of grown crystal for laser applications.The relative second harmonic generation efficiency of 2-methlquinolinium L-malate crystal was found to be two times greater than that of KDP.
关键词： Photoluminescence,Optical band gap,SHG studies,Laser damage threshold,Crystal growth
更新于2025-09-10 09:29:36
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Novel chromophore with tricyanocyclopentenone electronic acceptor and its application in organic EO polymers
摘要： Novel organic second nonlinear optical chromophore GL-1 based on tricyanocyclopentenone (TCNP) electronic acceptor group were designed and synthesized in this paper. The structure of chromophore GL-1 is characterized by mass spectrum and nuclear magnetic resonance spectroscopy. Chromophore FTC based on traditional tricyanofuran (TCF) electronic acceptor was also prepared as the contrast. Their delocalized energy levels were estimated by UV–Vis spectra. Their thermal properties were studied by thermogravimetric analysis. Obviously, chromophore GL-1 showed lower delocalized energy levels and higher thermal decomposition temperature (just about 286 °C). Electro-optics polymers prepared based on chromophore GL-1 showed the largest SHG coefficients of about 119 pm/V, which was about two times higher than chromophore FTC (about 68 pm/V). These advantages of chromophore GL-1 are attributed to the improvement of first order hyperpolarizability and the attenuatation of intermolecular dipole interaction by the introduction of tricyanocyclopentenone electronic acceptor. And in another word, tricyanocyclopentenone electronic acceptor may be a promising way to drastically change the nonlinear optical features of the titled compounds and show a direction of designing new electron acceptor in the field of nonlinear optical materials.
关键词： organic EO polymers,SHG coefficients,nonlinear optical chromophore,tricyanocyclopentenone,electronic acceptor
更新于2025-09-10 09:29:36
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Second and third order nonlinear optical studies of a novel thiophene substituted chalcone derivative
摘要： A noncentrosymmetric chalcone derivative (E)-1-(thiophen-2-yl)-3-(3, 4, 5-trimethoxyphenyl) prop-2-en-1-one (TTMP) was synthesized using Claisen Schmidt condensation approach and single crystals were grown using slow evaporation method. The grown TTMP crystals crystallises in orthorhombic structure with Pna21 space group. The intermolecular interactions of the TTMP crystals were envisioned by Hirshfeld surface analysis (HSA). Further, the structural conformations of the crystal were carried out by using 1H NMR, FTIR and FT-Raman spectral analysis. The UV-Vis-NIR spectrum of the sample clearly shows the prime transparency in the entire visible and near infrared region. Thermal studies (TG/DTA/DSC) of the TTMP sample shows excellent thermal stability and phase transition and also noticed that crystal was most stable up to 152.65 0C. The second harmonic generation efficiency was obtained for the crystals using Nd:YAG laser and is to be 1.93 times that of urea . The third order nonlinear absorption coefficient (β), nonlinear refractive index (n2), third-order nonlinear susceptibilities (χ (3)), second order hyper polarizability (γh) and optical limiting thresholds were determined by Z-scan technique using the Diode-Pumped Solid State (DPSS) Continuous Wave (CW) laser. The results suggest that the TTMP molecules are promising materials for optoelectronic device applications.
关键词： Hirshfeld surfaces,Optical limiting,SHG,Z-scan,Single crystal,Chalcones
更新于2025-09-09 09:28:46
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Anapole Resonances Facilitated by High Index Contrast between Substrate and Dielectric Nanodisk Enhance Vacuum Ultraviolet Generation
摘要： Anapole modes are known to be excited only in high-index nanoparticles. Here we show that the nanodisks made of dielectric materials with much lower refractive indices, such as LiNbO3, can generate anapole modes, provided that they are supported by metallic or near-zero-index substrate. The important parameter for exciting anapole mode is the index contrast between nanodisk and substrate, rather than the refractive index of the nanodisk. We numerically demonstrate highly efficient coherent generation of vacuum ultraviolet with the efficiency higher than 10-2 % based on the second-harmonic generation via the excitation of anapole modes in LiNbO3 nanodisks supported by aluminum substrate. Highly efficient vacuum ultraviolet nanosource proposed in this work can find important applications for spectroscopic and sensing purposes at the nanoscale.
关键词： Second-harmonic generation (SHG),Anapole mode,Refractive index,Nanodisks,Vacuum ultraviolet (VUV)
更新于2025-09-09 09:28:46
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Investigation on Physical Properties of Semiorganic Nonlinear Optical Glycine Zinc Sulfate Single Crystal
摘要： Nonlinear optical single crystals of Glycine Zinc Sulfate (GZS) were grown by slow evaporation technique. Single crystal X-ray diffraction analysis revealed the crystal system and lattice parameter values. Powder X-ray diffraction analyses have been carried out and the diffraction patterns have been indexed. The optical properties of the crystals were determined using UV-Visible spectroscopy. Optical constants such as band gap, refractive index, extinction coefficient and electric susceptibility were determined from UV-Visible spectroscopy. The refractive index was determined using Brewster’s angle method. Hardness of the GZS crystal was estimated by Vicker’s hardness studies. Second Harmonic Generation (SHG) of GZS crystal was investigated by Kurtz powder technique. The dielectric constant and dielectric loss measurements were carried out for different temperatures and frequencies. The photoconductivity studies confirm that the grown crystal has negative photoconductivity nature. In order to investigate the growth mechanism and surface features, etching studies are carried out for the crystal.
关键词： NLO,single X-ray diffraction,SHG,UV-Vis-NIR spectrophotometer,dielectric loss studies,dielectric constant
更新于2025-09-09 09:28:46
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Corneal Fibroblast Migration Patterns During Intrastromal Wound Healing Correlate With ECM Structure and Alignment
摘要： PURPOSE. To assess keratocyte backscattering, alignment, morphology, and connectivity in vivo following a full-thickness corneal injury using the Heidelberg Retina Tomograph Rostock Cornea Module (HRT-RCM), and to correlate these findings with en bloc three-dimensional (3-D) confocal fluorescence and second harmonic generation (SHG) imaging. METHODS. Rabbit corneas were scanned in vivo both before and 3, 7, 14, and 28 days after transcorneal freeze injury (FI), which damages all corneal cell layers. Corneal tissue was also fixed and labeled for f-actin and nuclei en bloc, and imaged using 3-D confocal fluorescence microscopy and SHG imaging. RESULTS. Using the modified HRT-RCM, full-thickness scans of all cell layers were consistently obtained. Following FI, stromal cells repopulating the damaged tissue assumed an elongated fibroblastic morphology, and a significant increase in cellular light scattering was measured. This stromal haze gradually decreased as wound healing progressed. Parallel, interconnected streams of aligned corneal fibroblasts were observed both in vivo (from HRT-RCM reflection images) and ex vivo (from f-actin and nuclear labeling) during wound healing, particularly in the posterior cornea. Second harmonic generation imaging demonstrated that these cells were aligned parallel to the collagen lamellae. CONCLUSIONS. The modified HRT-RCM allows in vivo measurements of sublayer thickness, assessment of cell morphology, alignment and connectivity, and estimation of stromal backscatter during wound healing. In this study, these in vivo observations led to the novel finding that the pattern of corneal fibroblast alignment is highly correlated with lamellar organization, suggesting contact guidance of intrastromal migration that may facilitate more rapid wound repopulation.
关键词： SHG imaging,confocal microscopy,corneal wound healing,extracellular matrix
更新于2025-09-04 15:30:14