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Extensive Study of Rhodanine-Arylamine-Based Chromophores: Consolidated Optical, DFT/TD-DFT and Non-Linear Optical Properties
摘要： Three push-pull rhodanine-arylamine based D-π-A dyes (2a-2c) are prepared to study the effect of donor on electronic, linear and nonlinear optical properties. The dyes, 2a,2b and 2c have a vinyl spacer conjugated with triphenylamine, julolidine, and carbazole donors respectively, with a methoxy group and rhodanine-3-acetic acid. The dyes exhibited solvent dependent absorption-emission up to the red region with large Stokes shifts (2a = 77-130 nm). This dyes possess charge transfer characteristics as established by transition dipole moment (μeg), dipole moment ratio (μe/μg), Generalised Mulliken-Hush analysis, and electron distribution (DFT). The non-linear optical study revealed that quadratic hyperpolarizability (μβCT) are 1098.9 (2a), 515.0 (2b) and 339.6 x 10-48 e.s.u. (2c) depending on donor strength. The intrinsic hyperpolarizabilities fall below βint0 = 10-3/2 limit i.e. less than unity. Solvatochromic two-level model is used to study the trends in two photon cross-section (σ2PA). The dye 2a exhibited high σ2PA, 216 GM (λmax 485 nm and 564 nm). The dyes 2a and 2c with analogue dye 3a show reverse saturable absorption (RSA) therefore, show positive third order nonlinear absorption coefficient, β and reasonable values of third order nonlinear susceptibility and high laser damage threshold. The Re χ(3) factors are responsible for the high values of χ(3) in the range of 0.77 to 8.09 x 10-12 e.s.u. Therefore, this material would serve as good candidate in the photonic application.
关键词： hyperpolarizability,Z scan,Arylamine donors,σ2PA,LDT
更新于2025-09-23 15:23:52
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Effect of acceptor moieties on static and dynamic first hyperpolarizability of azobenzene chromophores
摘要： The effect of acceptor on static and dynamic first hyperpolarizability, β, of trans- and cis-isomers of azochromophores AAB-DCV and AAB-TCV is studied. Calculations were performed by MP2 and DFT with three density functionals: M06-2X, CAM-B3LYP and ωB97X-D in gas phase and chloroform. Dynamic first hyperpolarizabilities were calculated by TD-DFT at 1.165 and 0.65 eV. The first hyperpolarizability values for trans-isomers are approximately three times greater than those for cis-isomer; solvent effect is essential comprising 2.7 and 3.2 times growth for static values for AAB-DCV and AAB-TCV, respectively, the corresponding dynamic estimations for βtot(2ω) being slightly smaller (2.2 and 2.6 times).
关键词： Dynamic characteristics,MP2,Azochromophore,Solvent effect,Acceptor effect,First hyperpolarizability,Density functional theory,TD-DFT
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Method for Calculating Electronic Polarizability of Water Molecules and Refractive Index
摘要： A method for calculating the electronic polarizability of water molecules is proposed. In the approximation of this method, the electronic components of the hyperpolarizability of the first and second order for the water molecule are determined.
关键词： water molecule,electron polarizability,refractive index,hyperpolarizability,electronic polarizability,molar refraction
更新于2025-09-23 15:22:29
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Enhanced nonlinear optical properties of porphyrin with an extended π-conjugated bridge
摘要： In this work, a series of molecules with an extended π-conjugated bridge have been theoretically designed based on porphyrin, where -(CH=CH)n- (n = 1–4, 8, 12) chain is served as an extended π-conjugated bridge. It is found that all molecules exhibit large energy gaps in the range of 3.484–4.151 eV for porphyrin-(CH=CH)n-NH2, and 3.624–4.250 for porphyrin-(CH=CH)n-NO2. The maximum absorption wavelengths of all molecules show a red shift trend with increasing -(CH=CH)n- length, which leads to small transition energy. It is observed that long chain brings these molecules the large first hyperpolarizability, which are 1.04 × 105 au for porphyrin-(CH=CH)12-NH2, 1.26×105 au for porphyrin-(CH=CH)12-NO2. Moreover, compared with -(CH=CH)n-NH2 with the same chain length, -(CH=CH)n-NO2 chain can achieve larger nonlinear optical response. It is hoped that the research in this paper can provide a new strategy for the experimental design of nonlinear optical materials.
关键词： First hyperpolarizability,Porphyrin,An extended π-conjugated bridge
更新于2025-09-23 15:22:29
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Effect of Fluorination on Bandgap, First and Second order Hyperpolarizabilities in Lithium Substituted Adamantane: A Time Dependent Density Functional Theory
摘要： Time dependent density functional theory is used to systematically examine the band gap variation of Li-substituted adamantanes upon fluorination. It is realized that the absorption wavelength of Li-Adamantane can be fine tuned within UV-Visible region by changing the degree of fluorination. The static and dynamic hyperpolarizabilities of fluorinated Li-Adamantane derivatives were computed using coupled perturbed Kohn Sham theory. In this article, we report Pockel, dc-Kerr, ESHG, degenerate four wave mixing coefficients and nonlinear refractive indices from the first and second order hyperpolarizability calculations. A high positive nonlinear refractive index and significant second harmonic generation efficiency at Nd:YAG Laser wavelength are observed in F3Li-Adm derivative.
关键词： adamantane,non linear responses,hyperpolarizability,TDDFT
更新于2025-09-23 15:21:21
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Recent advances with electro-optic polymers
摘要： In recent years the electro-optic polymers emerged as an important branch of material science. This growth and interest is fundamentally motivated by practical application of these materials in second-order nonlinear optics and in waveguiding configuration. Indeed, these materials marry excellent optical quality of amorphous r bonded polymers with enhanced first hyperpolarizability of imbedded organic nonlinear optical molecules. Although a big progress was achieved with them, concerning particularly the science, understanding and applications, some problems remain still incompletely solved, particularly the stability of induced polar order by the application of external electric field and the molecule aggregation. In this review paper we recall techniques of thin film fabrication, poling, characterization of NLO properties and discuss more precisely problems of molecule aggregation as well as the temporal decay of polar order. A novel 3D second-order NLO chromophores, namely the [2] paracyclophanes, which may help to limit the aggregation, are proposed. We show, in particular, that this molecule can be poled in doped PMMA thin films. Practical applications of electro-optic polymers are also reviewed and discussed.
关键词： pockels effect,electro-optic polymers,electric field poling,first hyperpolarizability,second harmonic generation,[2] paracyclophane,functionalized polymers
更新于2025-09-23 15:21:01
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Structure, electrical and nonlinear optical properties of $$\hbox {M@C}_{20}$$M@C20 (M?=?Li, Na, K, Be, Mg and Ca) nanoclusters
摘要： The decoration of Li, Na, K, Be, Mg and Ca metal atoms on C20 fullerene was studied using the density functional theory (DFT) method. It was shown that the structure of the fullerene was intensely affected by the metal atom present. All metal atoms have exothermic adsorption on C20 fullerene, while Be has the highest value of adsorption energy, enthalpy and free energy. The presence of the metal atom also has a slight effect on Eg while the lowest value of Eg was obtained for Ca@C20. The calculations of polarizability and the ?rst hyperpolarizability show that the metal atoms highly in?uence fullerenes. Among metal atoms, Ca atom had the highest effect and the other metal atoms led to an increase of the ?rst hyperpolarizability to a value of approximately 42000 a.u. The time-dependent (TD)-DFT studies showed that Ca@C20 has the lowest excitation energies which is in agreement with the calculated ?rst hyperpolarizability.
关键词： alkali metal atom,C20 fullerene,?rst hyperpolarizability,NLO,Ca atom
更新于2025-09-23 15:21:01
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Giant Stark effect in coupled quantum wells: Analytical model
摘要： Coupled quantum wells have been proposed as candidates for highly polarizable structures due to their near-degenerate and dipole-coupled electronic states. Hence, many interesting applications in linear and nonlinear optics can be envisioned. We analyze this proposal considering a simple structure with a delta-function barrier separating the wells. While very substantial Stark shifts are certainly predicted for this geometry, perturbative estimates based on polarizabilities (and hyperpolarizabilities) fail beyond a critical ?eld strength that depends inversely on the barrier. Hence, a giant Stark effect due to near-degenerate states is invariably limited by a small critical ?eld. Our analytical (hyper) polarizability expressions are applied to ?nd quantitative Stark shifts for GaAs quantum wells and transition-metal dichalcogenide bilayers. The predicted Stark shifts and critical ?elds agree with the ?eld dependence observed in a range of available experiments.
关键词： Stark effect,hyperpolarizability,GaAs,transition-metal dichalcogenide bilayers,polarizability,coupled quantum wells
更新于2025-09-23 15:19:57
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UV irradiation induce NLO modulation in photochromic Styrylquinoline-Based Polymers: Computational and Experimental Studies
摘要： Functionalized photochromic materials have attracted a growing interest during the last few decades since they are promising materials to be used in optoelectronics and photonics. In this paper, the results of the nonlinear optical (NLO) investigation (second and third harmonic generation) of spin deposited high-quality thin films of styrylquinoline containing methacrylic polymers studied by using Maker fringes technique employing 30 ps laser pulses at fundamental wavelength of 1064 nm are presented. Photochromic styrylquinoline units were oriented in the thin films by corona poling technique promoting second order NLO activity. Strong dependence of the NLO response upon the structure of the polymers has been found, which is related to the different charge transfer within the styrylquinoline fragments. These investigations were completed by theoretical studies using HOMO-LUMO energy levels theory and the first and second order hyperpolarizability values. Good compatibility has been achieved between the theoretical and experimental results. Studied styrylquinoline-based polymers showed the contrast in NLO response after their trans-cis photoisomerization making them interesting for using in photonic devices.
关键词： NLO properties,second and first order hyperpolarizability,harmonic generation,functionalized polymers,DFT and TDHF calculations,styrylquinoline
更新于2025-09-23 15:19:57
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Experimental and theoretical investigations of 4-hydroxy L-proline cadmium chloride nonlinear optical crystal
摘要： The solution grown structure 4-hydroxy L-proline cadmium chloride (4HLPCC) single crystal has been done by means of X-ray diffraction method. The computational quantum mechanical modelling method was performed with B3LYP level and LanL2DZ basis set to determine optimized geometry, dipolar moment, linear polarizability, first order hyperpolarizability, atomic charges of various atoms, thermodynamic parameters, HOMO-LUMO energy gap and vibrational frequencies of 4HLPCC. The vibrational frequencies of 4HLPCC were observed experimentally through FTIR and FT-RAMAN analyses and compared with theoretical frequencies. The electric properties were detected by dielectric studies. The frequency doubling of the grown crystal was made with Kurtz-Perry powder technique.
关键词： Polarizability,4-hydroxy L-proline cadmium chloride,DFT,Nonlinear optical properties,Hyperpolarizability
更新于2025-09-23 15:19:57