N-烯丙基咔唑三羰基铬配合物的合成及其晶体结构和非线性光学性质研究

采用N-烯丙基咔唑配体与三氨三羰基合铬在二氧六环中回流反应,合成了标题化合物。通过元素分析I、R、1HNMR1、3CNMR、MS和X射线单晶衍射对其结构进行了表征。晶体结构分析表明,该化合物属于三斜晶系,空间群P-1,a=8.136 2(11),b=10.254 6(14),c=10.887 3(15),α=99.671(3)°,β=108.810(2)°,γ=111.073(2)°,Z=2。比较了目标化合物与其自由配体的电子吸收光谱,并用飞秒Z-扫描技术研究了目标配合物的非线性光学性质。     

Thermally stable interpenetrating polymer networks for second‐order nonlinear optical materials

We report several kinds of interpenetrating polymer networks (IPNs) with nonlinear optical (NLO) properties. DMA spectra show that the two components of the IPNs have good compatibility with each other. The NLO materials have good optical transparency. The thermal stability of alignment was improved and the poled order remained very high. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 7–9, 1999     

Synthesis of a diacetylene-containing polyisophthalate and its third-order nonlinear optical susceptibility

In order to obtain amorphous thin films of a polydiacetylene, a polyisophthalate containing a push–pull diacetylene chromophore was synthesized by the reaction of p-(N,N-diethanolamino)-p’-nitrodiphenylbutadiyne with isophthaloyl chloride in anhydrous 1-methyl-2-pyrrolidone. The polymer was soluble in organic solvents, such as chloroform, tetrahydrofuran, dimethylformamide, etc., and films with good optical quality were obtained by spin coating from its N-methyl-2-pyrrolidone solution. It was characterized by ¹H-NMR, IR, DSC, UV–Visible, X-ray, etc. The diacetylene groups underwent polymerization in the film when irradiated with UV light at 120 °C under Ar atmosphere, and it contained free radicals with a radical concentration of 10¹⁶ radicals/g. The third-order nonlinear optical susceptibility, χ⁽³⁾, of the polymer film measured by the Z-scan technique at 1064 nm was not noticeable, but when the film was heated and irradiated with UV light, a χ⁽³⁾ value of 6.4?×?10^?10 esu was obtained due to increase in π-conjugation by the formation of polydiacetylene in the side chain.     

Role of surface defects in the third order nonlinear optical properties of pristine NiO and Cr doped NiO nanostructures

Pristine NiO and 2% Cr doped NiO nanostructures are successfully synthesized by the modified auto–combustion method for the determination and improvement of linear and nonlinear optical behaviours, and for identifying them as suitable materials for optical limiting applications. Vibrational and linear optical properties of both nanostructures are investigated, and structural and morphological studies are carried out using XRD, FE-SEM, and HR-TEM. From the Kubelka-Munk model, the energy band gaps for pristine and doped samples are found to be 3.52 eV and 3.44 eV, respectively. Both pristine as well as Cr-doped NiO nanostructures reveal substantial nonlinear optical behaviour at the excitation wavelength of 532 nm, arising from the presence of strong reverse saturable absorption. The third order nonlinear absorption coefficients have values of the order of 10^?10 m/W and 10^?6 m/W, under pulsed (5 ns) and continuous wave laser excitations, respectively. These values confirm the suitability of these nanostructures for fabricating efficient optical limiting devices for safeguarding human eyes and optical sensors from hazardous laser radiation.     

Third-order nonlinear optical properties and two-photon absorption in polymers doped with p-phenyl sydnone

We report the measurements of the third-order susceptibilities and two-photon absorption in three different polymers doped with p-phenyl sydnone moiety viz., 2-benzylhydrazono-5-(3-p-tolylsydnone-4-yl)1,3,4,-thiadiazine, which is recently synthesized and characterized, with the prospective of reaching a good compromise between processability and high nonlinear optical properties. The measurements were done using nano second Z-scan at 532nm. The Z-scan spectra reveal a large negative nonlinear refraction coefficient n₂ of the order 10⁻¹⁴ cm²/W and a two-photon absorption β, which is determined to be the order of cm/GW. The absorption cross section is 10⁻⁴⁶ cm⁴ s/photon. The molecular second-order hyperpolarizability in PMMA matrix was calculated to be 1.47 × 10⁻³¹ esu, comparable with stilbazolieum derivatives, a well-known class of optical materials for photonics and biophotonics applications. The chromophore shows its optical power limiting behavior in all the three polymer matrices. All these results suggest that this moiety has potential for the application of all-optical limiting and switching devices. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and the third-order nonlinear optical properties of soluble polymers with different substituted azobenzene side chains

A series of soluble polyacrylates containing different azobenzene side chains have been synthesized via atom transfer radical polymerization (ATRP) technique, from which the side-chain nonlinear optical (NLO) polymers with controllable molecular weight and low polydispersity (1.1-1.4) have been obtained. The third-order NLO absorption and refraction coefficients were simultaneously determined by Z-scan technique. The polymerization activity of the azobenzene-containing acrylate monomers and the third-order NLO properties of the obtained polyacrylates were both dominated by the electronic effect of the different substituents in the azobenzene side chain. The results of Z-scan with and without an aperture showed that all the azobenzene-containing monomers and polymers have both nonlinear absorption and nonlinear refraction. The third-order NLO susceptibility (χ⁽³⁾) of all the azobenzene-containing samples under the laser irradiation is 1.0-5.0 × 10⁻¹¹ esu.     

Photoluminescence and third-order nonlinear optical limiting properties of Sn1-xNdxO2 thin films deposited via spray pyrolysis

In the present work, spray pyrolysis method was adopted to synthesis nano thin films of Sn_1-xNd_xO₂ (x = 0.01 to 0.1) possessing tetragonal structure with (1 1 0) plane orientation. Nd doping reduced the overall crystallinity of the films, however Sn_0.92Nd_0.08O₂ film showed crystallite size of 18.7 nm, similar to that of the pure film. The morphology changed to distinct grains at lower doping concentration, beyond which a fibrous nature evolved but again changed to smaller grains with further increase in the doping. The oxidation states of the constituent elements were confirmed using XPS. The transmittance of the films reduced due to incorporation of Nd ions. A decrease in the energy band gap was also noticed in the films following dopant addition. The PL emissions corresponding to the Nd ion transitions was found in the NIR region resulting from internal 4f-shell transitions of Nd³⁺ ions. Other defect related emissions like the one from oxygen vacancies also showed up in the UV and visible wavelength regions, which were responsible for a near white light emission. The third-order optical nonlinearity of the films was confirmed using the Z-scan technique. All the Sn_1-xNd_xO₂ films till 8 at. % of doping showed reverse saturable absorption. The highest and lowest nonlinear absorption coefficient was exhibited by Sn_0.92Nd_0.08O₂ and Sn_0.98Nd_0.02O₂ films, respectively. Depending on the Nd concentration, the films either showed self-focusing or self-defocusing behavior and influenced the nonlinear refractive indices of the films. The least optical limiting values among the doped films was obtained in the range of 1.73 kJ/cm² for Sn_0.92Nd_0.08O₂ films.     

Synthesis and optical properties of polyacetylenes containing nonlinear optical chromophores

High molecular weight polyacetylenes bearing nonlinear chromophoric pendants poly[4-ethynyl-4′-(N,N-diethylamino)azobenzene-co-phenylacetylene]s [poly(EAAB-co-PA)s] were synthesized in moderate yields by [Rh(nbd)Cl]₂-Et₃N. The azo unit in the copolymers can be effectively controlled by the monomer feed ratio. Whereas the homopolymer of EAAB possessed low solubility, all the copolymers, however, dissolved readily in common organic solvents when the poly(EAAB) molar content was less than 41.7%. The structures and properties of the polymers were characterized and evaluated by UV, NMR, optical limiting, and nonlinear optical analyses. All the copolymers possessed high stereoregularity and thermal stability (≥300 °C). They can attenuate intense laser pulses, with solutions of high concentrations showing better performances. The third-order nonlinear susceptibility of the copolymers was as high as 4.62×10⁻¹¹ esu, which are two orders of magnitude larger than those of poly(PA), and larger than that of poly(N-carbazoylacetylene), and poly(1-naphthylacetylene).     

Synthesis and characterization of azo‐based acrylate polymers for use as nonlinear optical materials

In this work, high molecular weight azo polymers were synthesized by incorporating the azo monomer into a base polymer through their reactive functional groups. Copolymers of methyl methacrylate and methacrylic acid (with varying concentrations of carboxylic acid group) were synthesized. These were then reacted with epoxy‐terminated azo molecule by carboxylic acid–epoxy reaction. The functionalized systems show excellent film homogeneity and optical clarity. The series of copolymers were characterized using FTIR, NMR, UV–vis spectrometry, gel permeation chromatography, elemental analysis, thermogravimetric analysis, and differential scanning calorimetry. The polymer films coated on ITO glass slides were poled and their order parameters were calculated to check the stability of oriented dipoles. Temporal stability, checked up to 120 h under ambient conditions, was found to be excellent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 425–431, 2007     

Second-order nonlinear optical properties of a photocrosslinkable epoxy-based polymer

The synthesis and characterization of a novel epoxy-based photocrosslinkable nonlinear optical (NLO) polymer exhibiting enhanced thermal stability is reported. The synthesized polymers show spectroscopic properties (NMR, IR, UV) in accordance with the proposed structures. A glass transition temperature (T_g) of 112°C and a thermal degradation temperature (T_d) of 310°C were recorded. The poled polymer film exhibits stable second-order nonlinear optical activity (d₃₃ = 19.5 pm/V) over a period of 500 h as characterized by the temporal response of the second harmonic signal at room temperature. © 1996 John Wiley & Sons, Inc.     

Studying optical and nonlinear optical properties of synthesized azo dyes doped in polymer and liquid crystal using birefringence and Z‐ scan techniques

The authors report the effect of the structure of new synthesized photo‐responsive azo dyes, based on N‐benzyl‐N‐ethyl‐aniline on their optical and nonlinear optical properties, when doped in polymer and liquid crystal (LC) hosts. Anisotropic response of dyes doped with polymer polymethyl methacrylate is studied using photo‐induced birefringence experiment and the optical nonlinearity of dyes doped in LC 5CB is measured using z‐scan technique. A correlation is established between dipole moment and optical/nonlinear optical response, which makes it possible to develop molecular design strategies to create structures with suitable anisotropic response and nonlinearity in various host systems for different applications. It is also shown how very little change in the structure of the dye may cause severe changes in the dipole moment and its nonlinear response. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Microwave dielectric and nonlinear optical studies on radio‐frequency sputtered Dy2O3‐doped KNN thin films

We report the effect of oxygen mixing percentage (OMP) on structural, microstructural, dielectric, linear, and nonlinear optical properties of Dy₂O₃‐doped (K_0.5Na_0.5)NbO₃ thin films. The (K_0.5Na_0.5)NbO₃ + 0.5 wt%Dy₂O₃ (KNN05D) ferroelectric thin films were deposited on to quartz and Pt/Ti/SiO₂/Si substrates by RF magnetron sputtering. An increase in the refractive index from 2.08 to 2.21 and a decrease in the optical bandgap from 4.30 to 4.28 eV indicate the improvement in crystallinity, which is also confirmed from Raman studies. A high relative permittivity (ε_r=281‐332) and low loss tangent (tanδ=1.2%‐1.9%) were obtained for the films deposited in 100% OMP, measured at microwave frequencies (5‐15 GHz). The leakage current of the films found to be as low as 9.90×10^?9 A/cm² at 150 kV/cm and Poole‐Frenkel emission is the dominant conduction mechanism in the films. The third order nonlinear optical properties of the KNN05D films were investigated using modified single beam z‐scan method. The third order nonlinear susceptibility (?χ⁽³⁾?) values of KNN05D films increased from 0.69×10^?3 esu to 1.40×10^?3 esu with an increase in OMP. The larger and positive nonlinear refractive index n₂=7.04×10^?6 cm²/W, and nonlinear absorption coefficient β=1.70 cm/W were obtained for the 100% OMP film, indicating that KNN05D films are good candidates for the applications in nonlinear photonics and high‐frequency devices.     

Novel crosslinked nonlinear optical materials based on cellulose diacetate

Preparation of second‐order nonlinear optical (NLO) materials based on cellulose diacetate and melamine derivatives was attempted. The NLO chromophore DR19 was incorporated into the crosslinking network resulting from the reaction of cellulose diacetate with trimethylolmelamine or hexamethylolmelamine. The poled and cured NLO materials exhibited electrooptic coefficient (r₁₃) values of 1.11 or 1.03 pm/V, respectively, at a laser wavelength of 1550 nm, a modulation frequency of 12.7 kHz. The r₁₃ values decreased to 80 or 81.5% of the initial values after 4 days. The laser transmission loss was 0.50 or 0.44 db. The crosslinking materials showed better temporal stability than that of host/guest type materials, and 73% of the initial r₁₃ value remained after keeping the NLO film at 100°C for 15 h. No evident weight loss was found below 250°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2832–2837, 2006     

Synthesis and properties of novel crosslinkable second‐order nonlinear optical polymers based on 2,3,4,5,6‐pentafluorostyrene

Two crosslinkable second‐order nonlinear optical polymers were prepared by copolymerization of 2,3,4,5,6‐pentafluorostyrene, styrene (St), glycidyl methacrylate (GMA) and 1‐(4‐nitrophenyl)‐2‐(4‐{[2‐(methacryloyloxy) ethyl] ethylamino}‐phenyl) diazene (DR1M) via the sealed‐tube reaction technique. These polymers were characterized using ¹H, ¹³C and ¹⁹F NMR spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The crosslinkable polymers have high molecular weights, good organosolubility, excellent film‐forming properties and high glass transition (106–110 °C) and thermal decomposition temperatures (290–350 °C) after being crosslinked. Furthermore, the polymer films possess not only high values (12–16 pm V^?1) of electro‐optical coefficient (r₃₃) at 1.3 µm wavelength but also low optical loss (1.7 dB cm^?1) at 1.55 µm wavelength, which is of interest for applications in electro‐optical devices. Copyright © 2004 Society of Chemical Industry     

The synthesis of tetrahedral bipyridyl metallo-octupoles with large second- and third-order nonlinear optical properties

Two new 4,4′-bis(donor)-6,6′-diphenyl- 2,2′-bipyridine ligands and their corresponding D_2d (Cu^I, Ag^I, Zn^II) octupolar metal complexes were synthesized, and their linear and nonlinear optical properties were investigated. A single crystal X-ray structure was also determined for the bis[4,4′-bis(diethylaminostyryl)-6,6′-diphenyl-bipyridine]copper(I) complex, which revealed a distorded pseudo-tetrahedral geometry. Molecular second-order nonlinear optical properties were determined for the complexes using the Harmonic Light Scatterring technique at 1.91 μm. These metallo-chromophores display large first hyperpolarizabilities β_1.91 in the range of 211-340 × 10⁻³⁰ esu, which increase with the Lewis acidity of the metal ion. The two-photon absorption properties of the bipyridyl ligands and related complexes were determined using either the two-photon emission method for fluorescent compounds or the open aperture Z-scan technique for non emissive ones. The complexes display red-shifted two-photon absorption bands compared to their metal-ion free chromophores, as well as a large increase of the maximum two-photon absorption cross-sections.     

参数不确定非线性系统切换控制

针对一类含有不确定参数的非线性系统,基于其参数的不确定范围,设计多个滑模变结构控制器。在此基础上,基于一给定的指标切换函数构造切换控制器。在确保系统Lyapunov稳定性的前提下,被控对象的控制器按照预先设定好的切换条件,在多个控制器之间相互切换,从而极大地改善系统的瞬态响应。以工业机器人手臂为研究对象,针对机器人手臂运动方程构造滑模变结构控制器,并设计以输出误差为自变量的指标切换函数,基于此切换函数构造切换控制器,使机械手的控制器在多个控制器之间进行切换。针对不同的参数变化范围,研究切换控制的有效性。多个仿真实例表明切换控制能极大地改善控制品质。     

Photobleaching for the formation of nonlinear optical polymer waveguide devices

A simple but realistic kinetic model has been developed to delineate the refractive index profiles formed by photochemical reaction in nonlinear optical polymers. The effects of the absorption due to the unconverted reactant and the photoproduct are included in the model. The parameters required in the model are obtained from simple transmission experiments. The experimental results are consistent with the model. The refractive index profile is steeper when nonlinear optical polymeric materials are bleached by light with higher absorption. The rate of the bleach depth change becomes slower as the bleaching proceeds. Small absorption of bleaching light due to the photoproduct has significant effect on the resulting refractive index profiles. The photobleaching process is shown to be accelerated by the addition of a photosensitizer. Photobleaching time has been effectively reduced by a factor of 3–5. Linear and nonlinear optical properties of the polymer were little affected by the addition of the photosensitizer. It has also been demonstrated that the photobleaching technique can be utilized to tune the initial state of a directional coupler switch after completing the fabrication of the device. It was shown that successive cross states are passed from the initial cross state by selective bleaching of the gap region. The evolution of the refractive index profiles is successfully applied to predict the evolution of output state.     

Synthesis of a photo‐crosslinked stable nonlinear optical polymer and application to external electro‐optic measurement

A photo‐crosslinked side‐chain second‐order nonlinear optical polymer was synthesized with bis‐phenol‐A as the polymer backbone, p‐nitroaniline as the chromophore and cinnamyl group as the photo‐sensitizer. The characterization of the polymer was made by nuclear magnetic resonance, infrared, ultraviolet‐vis, and dynamic mechanical analysis methods. An electro‐optic film was obtained by spin coating of the polymer and corona poling then photo‐crosslinking reaction. An external electro‐optic measurement system was established based on the film and reflective light path configuration, and successfully applied to measure the electrical signals propagating on the under‐test circuits. The poled and crosslinked film showed high glass transition temperature (160°C) and improved chromophore orientation stability. The measuring principle was analyzed by electro‐optic tensor matrix and index ellipsoid methods. The results showed that the designed polymer film had the linear electro‐optic effect, the voltage sensitivity of the system was measured to be 5 mv/ at the condition of 1 kHz input signal. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1506–1512, 2000     

Studies on physico‐mechanical and optical properties,and WAXS of castor oil based polyurethane/polyacrylates interpenetrating polymer networks

Interpenetrating polymer networks (IPNs) of polyurethane (PU)/polyacrylates have been synthesized by sequential polymerization of castor oil, methylene diisocyanate (MDI), and acrylate monomers such as methyl acrylate (MA), methyl methacrylate (MMA), and ethyl acrylate (EA); with benzoyl peroxide (BPO) and ethylene glycol dimethyl acrylate (EGDM) as an initiator and crosslinker, respectively. The physico‐mechanical properties, such as density, surface hardness, tensile strength, percentage elongation at break, and tear strength; and the optical properties, like total transmittance and haze, of PU/polyacrylate IPNs have been reported. Microcrystalline parameters of IPNs have been computed by using wide angle X‐ray scattering (WAXS) recordings. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 764–773, 2005     

Synthesis and characterization of azo‐based methacrylate polymers with methoxy and nitro end groups for nonlinear optical applications

One new and three already described azobased methacrylate monomers with methoxy and nitro end groups and spacer length 2 and 6 were synthesized. These monomers were copolymerized with methyl methacrylate and the monomers as well as copolymers were characterized by classical spectroscopy techniques (FTIR, NMR, and UV‐VIS), gel permeation chromatography (GPC), elemental analysis and thermal analysis (TGA and DSC). The glass transition temperature of the polymers was found to be above room temperature and thermal decomposition temperatures above 100°C. All the polymers were amorphous in nature and formed excellent homogeneous films with good optical transparency. The polymer films coated on indium tin oxide glass slides were poled and their order parameters were calculated to check the stability of oriented dipoles. Few samples were also studied for their second harmonic generation properties. Temporal stability, checked up to 120 h at room temperature, was found to be quite satisfactory. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3497–3504, 2007