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Photonic and Electronic Properties of Fluoride Materials || Frequency-Doubling Oxide Fluorides, Borate Fluorides, and?Fluorooxoborates
摘要： The frequency-doubling (FD) materials that are able to expand the frequency ranges of lasers by second harmonic generation (SHG) are the core of the solid-state lasers. FD is a nonlinear optical (NLO) process, in which two input laser beams with the same frequency interacting with an FD material “combine” together to generate a new output laser with twice the frequency and half the wavelength of the initial light beams. This phenomenon was first demonstrated by Franken et al. in 1961. They irradiated a quartz sample using a laser beam with a wavelength of 694 nm, and observed the output light at 347.2 nm. FD is only allowed with coherent light and in mediums without inversion symmetry.
关键词： Nonlinear Optical Materials,Borate Fluorides,Second Harmonic Generation,Frequency-doubling,Fluorooxoborates
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
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Nonlinear optical and optical power limiting studies of Zn1-xMnxO thin films prepared by spray pyrolysis
摘要： Zn1-xMnxO (x=0, 0.02, 0.04, 0.06, 0.08 and 0.1) thin films were deposited at 723 K temperature on glass substrate using a solution of molarity of 0.0125M through spray pyrolysis method. X-ray diffractogram (XRD) analysis confirmed that all the films have (0 0 2) as a preferential orientation with hexagonal wurtzite structure. The increase of dopant marginally changed the crystallite size and lattice parameters. Surface morphology changes fibrous to spherical structure with an increase in doping. X-ray photoelectron spectroscope (XPS) measurements proved the occurrence of manganese is in the Mn2+ transition state along with Oxygen and Zinc content. The films showed ~90-80% transmittance in the visible region with increasing in Mn concentration. The energy band-gap reduced with increase in dopant, due to sp-d exchange interactions. The nonlinear optical (NLO) properties were studied using z-scan technique under continuous wave (CW) diode pumped solid-state (DPSS) laser operating at 532 nm wavelength. Reverse saturable absorption (RSA) behaviors observed in both undoped and Mn doped films which is attributed to two-photon absorption (TPA) process. The optical limiting properties were also studied, which suggests that the prepared thin films could be used as optical limiters in the visible region.
关键词： ZnMnO films,structural property,nonlinear optical properties,optical property
更新于2025-09-19 17:15:36
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Theoretical study on nonlinear optical properties of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole
摘要： The first-, second- and third-order nonlinear optical properties of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole in gas phase employing sum-over-states (SOS) method have been calculated for the first time. The ground state molecular structure of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole was obtained by the geometrical optimizations based on the B3LYP/6-31+G(d) level. The energy of excited states and transition dipole moments between different excited states were obtained by using the time-dependent density functional theory (TDDFT) based on the CAM-B3LYP/Sadlej POL level. Charge transfer during electron excitation was analyzed based on hole and electron distributions. Our calculations showed that the N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole has good nonlinear optical properties and its nonlinear optical properties arise from charge-transfer excitation and local excitation but charge transfer plays the leading role.
关键词： N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole,the time-dependent density functional theory (TDDFT),charge transfer,sum-over-states (SOS) method,nonlinear optical properties
更新于2025-09-19 17:15:36
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Broadband ultrafast nonlinear optical studies revealing exciting multi-photon absorption coefficients in phase pure zero-dimensional Cs <sub/>4</sub> PbBr <sub/>6</sub> perovskite films
摘要： Lead halide perovskite nanocrystals (NCs) apart from their overwhelming optoelectronic applications have recently demonstrated promising nonlinear optical (NLO) properties such as strong two-photon absorption cross-sections (～105 GM), two-photon fluorescence, and saturable absorption even at very high peak intensity. Zero-dimensional perovskite-related materials (0-D PRMs) are a new class of materials offering a high exciton binding energy (Eg ≥ 180 meV) with a strong photoluminescence (PL) quantum yield in few cases. Herein, we report the broadband third-order NLO properties of phase pure Cs4PbBr6 0-D PRM achieved using the Z-scan and degenerate four-wave mixing techniques in the femtosecond regime. Considering the growing content of the fluorescent and non-fluorescent forms of this material, we have performed our studies on both of them. These perovskite NCs exhibited strong multi-photon absorption properties in the near-infrared region with two-photon absorption (2PA) (cross-section, σ2 = 10?43–10?44 cm4 s equivalent to ～106 GM) in the 500–800 nm region, three-photon absorption (3PA) (cross-section, σ3 ～10?73 cm6 s2) in the 900–1200 nm region and four-photon absorption (4PA) (cross-section, σ4 ～10?100 cm8 s3) in the 1300–1500 nm spectral region. These multi-photon absorption processes are explained using a simple band diagram. The measured NLO coefficients and cross-sections are fairly large when compared to some of the earlier reports on perovskite-based NCs. Cs4PbBr6 0-D PRM also demonstrated a large third-order NLO susceptibility χ(3) (～10?7 esu), which can be attributed to the strong quantum confinement arising from spatially isolated, exciton containing individual [PbBr6]4? octahedron. These results clearly suggest the potential of 0D-PRMs in applications such as photonics and ultrafast all-optical switching devices.
关键词： Z-scan,perovskite nanocrystals,ultrafast optics,degenerate four-wave mixing,multi-photon absorption,nonlinear optical properties
更新于2025-09-19 17:15:36
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Cation-tuned synthesis of the A <sub/>2</sub> SO <sub/>4</sub> ·SbF <sub/>3</sub> (A = Na <sup>+</sup> , NH <sub/>4</sub><sup>+</sup> , K <sup>+</sup> , Rb <sup>+</sup> ) family with nonlinear optical properties
摘要： Four antimony fluoride sulfates named A2SO4·SbF3 (A = Na+, NH4+, K+, Rb+) have been successfully synthesized using a hydrothermal method by introducing Sb3+ cations with a stereochemically active lone pair in sulfates and subsequently tuning the structure through the second monovalent cations. All of the title compounds are stoichiometrically equivalent materials which share a common structural motif composed of a distorted SO4 tetrahedron and an asymmetric SbF3 polyhedron. However, the macroscopic centricities of these four compounds are significantly influenced by the size and coordination environment of cations; Na2SO4·SbF3 crystallizes in centrosymmetric space groups Cmca and (NH4)2SO4·SbF3 in Pbca, while K2SO4·SbF3 and Rb2SO4·SbF3 crystallizes in noncentrosymmetric space group P212121. Complete characterization including thermal analyses, infrared and UV-vis spectroscopy, and theoretical calculations is also reported. Powder second harmonic generation measurement for noncentrosymmetric K2SO4·SbF3 and Rb2SO4·SbF3 indicated that both of them are type I phase-matchable.
关键词： hydrothermal synthesis,cation tuning,nonlinear optical materials,antimony fluoride sulfates,second harmonic generation
更新于2025-09-19 17:15:36
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Theoretical design, synthesis and studies on the solvatochromic behaviour of low band gap phenylenevinylene based copolymers
摘要： A new series of low band gap phenylenevinylene based copolymers was designed by employing density functional theory in the periodic boundary condition using HSE06 exchange correlation functional using 6-31G basis set and synthesized via the Gilch polymerization. The theoretical band gap of the copolymers MD-CA-PPV, MD-FL-PPV, MD-PT-PPV and MD-AN-PPV were found to be 1.98, 2.07, 2.31 and 1.99 eV respectively using the DFT/HSE06/6-31G calculation and the optical band gap of 1.96, 2.03, 2.01 and 1.98 eV respectively, according to the onset edge of lower energy peak of the polymers in solution. The experimental results supported the theoretical prediction. Solvatochromic behaviour of the synthesized copolymers was studied thoroughly in toluene/acetonitrile mixtures of varying polarity at room temperature. The absorption spectrum of the PPV polymers was sensitive to solvent effects which showed bathochromic and hypsochromic shifts with increasing solvent polarity indicating that the transitions involved were π-π* and n-π*. The ground and excited state dipole moments were calculated using solvatochromic correlations. Onsager radius determined from ab initio calculation was used in the determination of dipole moments. The change in the dipole moment (Δμ) was calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter (ET(30)) and values are compared. It was observed that the excited state dipole moment (μe) was larger than its ground state (μg) counterpart. This indicated that a substantial redistribution of the π-electron densities occurred in the more polar excited state for the selected phenylenevinylene polymers. The third-order nonlinear optical (NLO) properties of the copolymers, evaluated by Z-scan method with nanosecond laser beam at 532 nm, are reported. The nonlinear absorption coefficient of the copolymers were calculated to be 0.17×10-10, 2.06 × 10-10, 0.63 × 10-10 and 2.83 × 10-10 esu, respectively for MD-CA-PPV, MD-FL-PPV, MD-PT-PPV and MD-AN-PPV which certified that the polymers showed semiconductor properties.
关键词： Nonlinear optical properties,Solvatochromic properties,Gilch polymerisation,Density functional theory,Poly(p-phenylenevinylene) derivatives
更新于2025-09-19 17:15:36
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Second-order nonlinear optical properties of Stenhouse photoswitches: insights from density functional theory
摘要： We report the first investigation of the second-order nonlinear optical (NLO) properties of donor–acceptor Stenhouse adducts (DASAs), an emerging class of colored photochromes that undergo photoswitching with visible light to a colorless form. By using time-dependent density functional theory, we provide insights into the relationships linking the nature of the chemical substituents to the amplitude and contrasts of the NLO response. Solvent and frequency dispersion effects are also analyzed. The calculations predict that DASAs behave as high contrast NLO switches, a finding that extends their potential applications to photo-responsive NLO materials and devices.
关键词： photoswitching,Stenhouse photoswitches,nonlinear optical properties,density functional theory,second harmonic generation
更新于2025-09-19 17:15:36
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PbS and PbS/CdS quantum dots: Synthesized by photochemical approach, structural, linear and nonlinear response properties, and optical limiting
摘要： In this work, PbS and PbS/CdS core–shell quantum dots (QDs) were synthesized by a new photochemical approach. Prepared QDs were characterized by means of x-ray diffraction (XRD), ?eld emission scanning electron microscopy (FESEM), energy dispersive x-ray analysis (EDAX), UV–Vis, and Z-scan analyses. Synthesized QDs were in a cubic phase with a spherical morphology, and the crystallite sizes are estimated using the strain–size method. A uniform shift of Bragg diffraction peaks and quenching (200) Bragg plane are interpreted as the growth of the CdS shell. Linear optical properties were investigated using Urbach analysis and Tauc formula. It was found that the density of states of QD conduction and valence bands are three dimensional. The estimated sizes of PbS QDs and PbS/CdS using exciton absorption peaks at room temperature are 1.8 and 2.7 nm, respectively, which are in good agreement with the strain–size plot analysis. The growth of the CdS shell resulted in a considerable decrease in the nonlinearity refractive index and a signi?cant increase in the nonlinear absorption.
关键词： PbS/CdS,photochemical synthesis,PbS,optical limiting,quantum dots,nonlinear optical properties
更新于2025-09-19 17:13:59
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[IEEE 2020 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus) - St. Petersburg and Moscow, Russia (2020.1.27-2020.1.30)] 2020 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus) - Study of Long-term Pulsed Laser Irradiation Effect on SWCNT-Water Dispersion
摘要： In this paper, we studied the effect of long-term pulsed laser radiation from visible range on an aqueous dispersion with single-walled carbon nanotubes with a concentration of 0.005%. The dependence of the normalized temperature dependence, and transmission on nonlinear optical characteristics were determined. In several minutes of irradiation, bubbles appeared in the dispersion and enlightenment was observed, i.e. increase in transmission. It was determined that an aqueous dispersion with carbon nanotubes retains its optical characteristics for 600 pulses at a laser pulses frequency of 10 Hz and power of 230 mW.
关键词： carbon nanotubes,thermograms,pulsed laser radiation,nonlinear optical properties,optical limiters
更新于2025-09-19 17:13:59