Second-order Nonlinear Optical Chromophores Research Articles

ペルフルオロシクロペンテニル部位で結合したアゾ系の二次非線形光学クロモファーの配向緩和

ペルフルオロシクロペンテニル部位で結合したアゾ系の二次非線形光学クロモファーの配向緩和

Synthetic approach for the incorporation of second-order nonlinear optical chromophores containing furan groups, into methacrylate copolymers

Nonlinear optical chromophores with furan units incorporated in the conjugated system were synthesized. Their second-order nonlinear response was determined by electric-field-induced second-harmonic generation (EFISHG) measurements. Off-resonant values μβ 0 as high as 431.10 −48 esu were obtained. The D πA (donor-accepted conjugated) systems were incorporated as side chain into MMA-chromophore functionalised methacrylate copolymers in various concentrations.

Synthesis and characterization of thermally crosslinked polyimide with second-order nonlinear optical chromophore

Synthesis of three novel crosslinked polyimides with push-pull azobenzene group has been developed. 4-Nitre4′-[N, N-bis (2-aminoethyl)]aminoazobenzene was first prepared, then poly(amic acid) prepolymer, one crosslinkable component, was obtained by aminolysis of alternating styrene-maleic anhydride copolymer, alternating thiophene-maleic anhydride copolymer or alternating benzofuran-maleic anhydride copolymer with it, and at last the crosslinked second-order nonlinear optical polyimide was synthesized by crosslinking and imidizing poly (amic acid) prepolymer with corresponding alternating copolymer. The crosslinking and imidizing processes were studied by IR and UV-Vis spectra. The chromophore density in one of the crosslinkable components, poly(amic acid) prepolymer, and the thermal stability of crosslinked polyimide thin film were measured by UV-Vis spectra.

Synthesis and nonlinear optical properties of end-group modified aromatic esters as chained chromophores

We synthesized aromatic ester derivatives with some electron accepting groups at molecular ends as new class of nonlinear optical (NLO) active chromophores (ArESn-X, n = 2, 3, X = CN, CF3, NO2, DCV). Some second-order NLO properties for poled polymer films consisting of poly(methyl methacrylate) (PMMA) doped with 10 wt.-% ArESn-X (ArESn-X/PMMA) were investigated. UV/vis spectra of these polymer films have cutoff wavelengths (λco) of about 300∼380 nm, which are much shorter than in the case of p-nitroaniline (pNA) (λco = ca. 450 nm) as a typical strong donor-acceptor (D-A) molecule. In addition, some of these polymer films exhibited larger second-order nonlinear coefficient (d33) values than PMMA film doped with 10 wt.-% pNA (pNA/PMMA) (2.8 × 10−9 esu). Namely, ArES3-CN (d33 = 3.1 × 10−9 esu, 10 wt.-% in PMMA), ArES3-NO2 (3.0 × 10−9 esu, 10 wt.-% in PMMA) and ArES2-DCV (4.0 × 10−9 esu, 10 wt.-% in PMMA) showed not only excellent second-order NLO activity but also excellent transparency in the visible region (λco = 304 nm (ArES3-CN), 340 nm (ArES3-NO2) and 370 nm (ArES2-DCV), respectively). Consequently, these compounds are believed to be promising chromophores for second-order nonlinear optics.

Synthesis and nonlinear optical properties of end-group modified aromatic esters as chained chromophores

We synthesized aromatic ester derivatives with some electron accepting groups at molecular ends as new class of nonlinear optical (NLO) active chromophores (ArESn-X, n = 2, 3, X = CN, CF 3 , NO 2 , DCV). Some second-order NLO properties for poled polymer films consisting of poly(methyl methacrylate) (PMMA) doped with 10 wt.-% ArESn-X (ArESn-X/PMMA) were investigated. UV/vis spectra of these polymer films have cutoff wavelengths (λ co ) of about 300-380 nm, which are much shorter than in the case of p-nitroaniline (pNA) (λ co = ca. 450 nm) as a typical strong donor-acceptor (D-A) molecule. In addition, some of these polymer films exhibited larger second-order nonlinear coefficient (d 33 ) values than PMMA film doped with 10 wt.-% pNA (pNA/PMMA) (2.8 x 10 -9 esu). Namely, ArES3-CN (d 33 = 3.1 x 10 -9 esu, 10 wt.-% in PMMA), ArES3-NO 2 (3.0 x 10 -9 esu, 10 wt.-% in PMMA) and ArES2-DCV (4.0 x 10 -9 esu, 10 wt.-% in PMMA) showed not only excellent second-order NLO activity but also excellent transparency in the visible region (λ co = 304 nm (ArES3-CN), 340 nm (ArES-NO 2 ) and 370 nm (ArES2-DCV), respectively). Consequently, these compounds are believed to be promising chromophores for second-order nonlinear optics.

Improved Temporal Stability of Electro-optic Property in Sol-gel Matrix bearing a Silylated Dye

We simply synthesized the triethoxysilane bearing the second-order nonlinear optical(NLO) active chromophore or chalcone derivatives. In order to improve the poor temporal stability of second-order NLO effect in sol-gel matrix, we introduced the photo-crosslink between the side chain. themselves. Photo-crosslink formation was confirmed with UV-VIS absorption and infrared vibrational spectroscopy. Under a polarized light, we investigated the decaying behavior of molecular order parameter after corona poling.

Second-order optical nonlinearity of thiazolylazo chromophores containing hydroxyl groups

Bathochromic thiazolylazo second-order nonlinear optical chromophores (NLOphores) having 2-hydroxyethyl group(s) in a molecule have been prepared. The tris(2-hydroxyethyl) derivatives showed the best relaxation behaviour among the non-, mono-, bis- and tris(2-hydroxyethyl) ones doped in poly(methyl methacrylate- co-methacrylic acid).

Synthesis of Novel Polysiloxanes Containing Charge Transporting and Second-Order Nonlinear Optical Functionalities with Atom Economical Constructs

Novel, highly functionalized polysiloxanes were prepared in which each repeat unit bears, on average, one charge transporting and one to two second-order nonlinear optical chromophores. Covalent attachment of charge-transporting carbazole or diphenylamine derivatives was realized through efficient Pt-catalyzed hydrosilylation. Poly(hydrogen methylsiloxane) was reacted with 9-(2-propenyl)carbazole or (N-phenyl-N-2-propenylamino)benzene, affording poly[methyl-3-(9-carbazolyl)propylsiloxane] and poly[methyl-3-(N,N-diphenylamino)propylsiloxane], respectively. Rather remarkable regiospecific bromination of the two arylamine-containing siloxane polymers was achieved using benzyltrimethylammonium chlorobromate, resulting in the formation of poly[methyl-3-(N(3,6-dibromocarbazolyl))propylsiloxane] and poly[methyl-3-(N,N-bis(4-bromophenyl)amino)propylsiloxane]. Pd-catalyzed Heck-type coupling of the arylbromide-bearing polysiloxanes with either vinylbenzenephosphonic acid diethyl ester or 4-nitrostyrene afforded st...

Improved Temporal Stability of the Second-Order Nonlinear Optical Effect in a Sol−Gel Matrix Bearing an Active Chromophore

A second-order nonlinear optical (NLO) chromophore (disperse red 1) was reacted with (3-isocyanatopropyl)triethoxysilane to form a functionalized silicon alkoxide precursor (SGDR1). To improve the temporal stability of the second-order NLO effect, we employed a thermal cross-link between the organic side groups themselves. (3-Glycidoxypropyl)trimethoxysilane was mixed with SGDR1 in tetrahydrofuran (SGDR1/GPTS). We compared the temporal stability of the poled samples with SGDR1 and SGDR1/GPTS. We investigated second-order NLO properties of sol−gel films by virtue of second harmonic generation (SHG) and linear electrooptic (E/O) coefficient measurements for the purpose. We achieved much improvement in the temporal stability of second-order NLO effect at high temperature with the heterogeneous films.

High-Performance Polyquinolines with Pendent High-Temperature Chromophores for Second-Order Nonlinear Optics

A series of high-temperature and chemically stable chromophores were covalently attached onto the polyquinoline backbones. These NLO side-chain polyquinolines possess high glass transition temperat...

Synthesis and non-linear optical properties of aromatic ester oligomers as chained chromophores

We synthesized some aromatic ester oligomers consisting of repeating units of oxy-1,4-phenylenecarbonyl group (ArESn, n = 2–4) as novel non-linear optical (NLO) active chromophores. Some second-order NLO properties for poled polymer films consisting of poly(methyl methacrylate) (PMMA) doped with 10 or 5 wt% ArESn and 10 wt% p-nitroaniline (pNA) were investigated. Comparison of the d33 value at the chromophore molar concentration [d33 (M)] for these polymer films indicated that the d33 (M) value of ArESn increases with an increase in n and ArESn with n more than 3 reveals a higher d33 (M) value than that of pNA. In addition, every ArESn has a cutoff wavelength (λco) of about 300 nm, which is much shorter than the case of pNA (λco = ca.45O nm). ArESn are concluded to be promising chromophores for second-order non-linear optics. © 1997 Elsevier Science Ltd.

Synthesis of polyamic acid possessing second-order nonlinear optical properties and its application to Langmuir Blodgett films

Tetracarboxylic dianhydride containing the second-order nonlinear optical chromophore thiophene-type stilbene with diethylamino and tricyanoethenyl substituents on each terminal was newly synthesized. Polyamic acid prepared from the tetracarboxylic dianhydride and N, N′-diaminodiphenyl ether was soluble in aprotic polar solvents and had an inherent viscosity of 0.2 dL/g. Polyimide obtained by heating of the polyamic acid at 160 °C was thermally stable to 240 °C. Polyimide Langmuir–Blodgett (LB) films were prepared by the precursor method through polyamic acid alkyl amine salts (the precursor of polyimide) with three kinds of alkyl amine. The precursor LB film had a Y-type structure and a good linear relationship between thickness and absorption at 650 nm in both precursor and polyimide LB films. Fourier-transform IR spectra before and after imidization indicated that the nonlinear optical chromophore remained in the polyimide LB film. It was found from the observation of transmission UV–visible spectra that the nonlinear optical chromophore was oriented more nearly perpendicularly in polyimide LB film than in the precursor LB film.

A new hyperbranched polymer with polar chromophores for nonlinear optics

A new three-dimensional hyperbranched polymer with 4-(2-cyano-2-methoxy-carbonylvinyl)aniline as a second-order nonlinear optical chromophore has been synthesized starting from 4-formyl- N,N-di(2-hydroxyethyl)aniline and cyanoacetic acid by a one-pot Knoevenagel polycondensation using 4-(dimethylamino)pyridine as a base. This hyperbranched polymer with a good solubility in polar organic solvents, such as N,N-dimethylformamide and methyl sulfoxide, was characterized by 1H n.m.r., i.r. and u.v.-vis spectroscopies. Differential scanning calorimeter analysis showed that this polymer exhibited a glass transition temperature at 86°C. The second-harmonic generation signal has been observed from the poled films of this hyperbranched polymer.

Photorefractivity in a Novel Polymer Composite with High Diffraction Efficiency and Broad Optical Transparency

A novel photorefractive polymer composite has been developed in which a new organic dye, 4-[N-(2-hydroxyethyl)-N-methylamino]-4‘-[(6-hydroxyhexyl)sulfonyl]stilbene, is used as a second-order nonlinear optical chromophore together with poly(N-vinylcarbazole) as the hole-transporting matrix, tricresyl phosphate as a plasticizer, and C60 as a photosensitizer. The photoconductive, electro-optic, and photorefractive properties of the material have been experimentally studied at wavelengths of 488, 514.5, and 632.8 nm. The amplitude and the phase dependencies of the electro-optic response have been investigated. The composite shows high photorefractivity over a broad wavelength range. Diffraction efficiencies between 20% and 40% as well as net two-beam coupling gains of 25−65 cm-1 have been obtained at wavelengths of 488, 514.5, and 632.8 nm.

Synthesis and Characterization of Functionalized Sol-Gel Materials for Electro-Optical Application

We simply synthesized the triethoxysilane bearing the second-order nonlinear optical(NLO) active chromophore in the side chain. In order to improve the poor temporal stability of second-order NLO effect, we introduced the thermal crosslink between the side chain themselves. We prepared two different silane solutions; one is composed of triethoxysilane with NLO chromophore (SGDR1) only. The other consists of SGDR1 and 3-glycidoxypropyl trimethoxysilane. Thermal crosslink formation was traced with in-situ infrared spectroscopy. We achieved much improvement of the temporal stability of second-order NLO effect utilizing this crosslinked composite system.

Recent Progress of Electro-optic Polymers for Device Applications

AbstractElectro-optic (E-O) polymers have drawn great interest in recent years because of their potential applications in photonics devices such as high speed modulators and switches, optical data storage and information processing1–2. In order to have suitable materials for device fabrication, it is essential to design and develop polymeric material systems (active and passive polymers) with matched refractive indices, large E-O coefficients, good temporal and photochemical stability3–8 The E-O response of an active polymer commonly arises from the electric field induced alignment of its second-order nonlinear optical (NLO) chromophore, either doped as a guest/host system or covalently bonded as a side-chain. Because of the strong interaction among the electric dipoles, the poled structure is in a meta-stable state; the poled NLO chromophores which possess large dipole moment will tend to relax back to the randomly oriented state. As a result, the stability of the poled structure strongly depends on the rigidity of the overall material system. As it might be expected, the continuous increases of the rigidity and Tg of poled polymers imposes constraints on the selection of suitable chromophores that can survive the hightemperature poling and processing conditions. To circumvent this problem, we have developed a series of chromophores that possess conformation-locked geometry and perfluoro-dicyanovinylsubstituted electron-accepting group which demonstrate both good thermal stabilty and nonlinearity. This paper provides a brief review of these highly efficient and thermally stable chromophores and polymers for device applications.

Synthesis of novel conjugated oligomers for second-order nonlinear optics: incorporation of a central spacer as a conjugation modulator

A new series of second-order nonlinear optical chromophores has been synthesized that consists of a conjugated segment end-capped with an electron acceptor and an electron donor, respectively, and a central spacer intended to modulate the electro-optical effect. Conjugated chains have been tailored with trans-vinylene-1,5-thienylene as the building unit and N,N-dimethylamino and nitro groups as the donor–acceptor pair. Four spacers have been incorporated into the central part of the conjugated oligomers, which range from saturated to totally unsaturated functions, i.e. from methylene to vinylene units. The general strategy relies upon two consecutive Wittig or Wittig–Horner reactions between the spacer precursor and an aromatic phosphonium or phosphonate bearing the strong electron donor and the acceptor, respectively. Two synthetic pathways have been studied. The first procedure is based on the use of a symmetric precursor for the spacer. However, a reaction byproduct is formed, which must be removed and decreases the reaction efficiency. The second approach requires an asymmetric precursor for the spacer, the synthesis of which is a multistep process. In order to evaluate the effect of the spacer, a completely conjugated oligomer has been prepared by the one-step coupling of two conjugated segments end-functionalized by the electron donor and the acceptor, respectively.

Design of optimized photorefractive polymers: A novel class of chromophores

It is demonstrated that the microscopic mechanism of the photorefractive (PR) effect in organic composites with low glass transition temperatures involves the formation of refractive index gratings through a space-charge field-modulated Kerr effect. A tensorial formulation of the macroscopic aspects of the PR Kerr effect and its microscopic interpretation is presented. The second-order dipole orientation term containing the anisotropy of the first-order optical polarizability α(−ω;ω) is shown to yield the dominant contribution to the Kerr susceptibility χ(3)(−ω;ω,0,0). A class of special chromophores having negligible second-order polarizabilities β(−ω;ω,0) and large dipole moments μ has been identified in order to optimize this term. These chromophores are not subject to the efficiency-transparency tradeoff typically encountered with second-order nonlinear optical (NLO) chromophores, providing highly transparent materials with large PR Kerr response. Contrary to previous approaches in this field, the best-performing PR polymers are then expected to employ chromophores that would be useless for second- order applications (negligible β). We report PR of the material 30% 2,6-di-n-propyl-4H-pyran-4-ylidenemalononitrile (DPDCP): 15% N,N′-bis(3-methylphenyl)- N,N′-bis(phenyl)benzidine (TPD):55% poly(methyl methacrylate) (PMMA):0.3% C60 as an illustration of this principle. A 100 μm thick film of this material exhibits a steady-state diffraction efficiency of η=25% and net two-beam coupling of Γ=50 cm−1 at a bias field of 100 V/μm and a wavelength of 676 nm. The macroscopic Kerr susceptibility of the material is related to molecular electronic properties of the chromophore DPDCP which were independently determined by experiments in solution and by quantum chemical calculations.

Synthesis of sulfone-substituted thiophene chromophores for second-order nonlinear optics

A new series of conjugated thiophene compounds 1–4 containing methylsulfonyl and phenylsulfonyl acceptors have been synthesized which possess efficient second-order optical nonlinearities, high thermal stability and good transparency for use as nonlinear optical materials.

The symmetry of functionalized poly(propylene imine) dendrimers probed with hyper-Rayleigh scattering

Dendrimers are well-defined highly branched macromolecules that emanate from a central core and are synthesized through a stepwise, repetitive reaction sequence. In this study, different generations of a poly(propylene imine) dendrimer have been functionalized with second-order non-linear optical chromophores. The non-linear optical properties of these macromolecules have been investigated using the hyper-Rayleigh scattering technique. The sensitivity of this technique to molecular symmetry is exploited. The measurements show, in a unique way at the molecular level, that the dendrimers in solution form globular structures at generations with 32 and 64 4-dimethylaminophenylcarboxamide end-groups with restricted mobility of the end-groups.