摘要:

Nonlinear optical susceptibilities of conjugated polymers are studied in the Su-Schrieffer-Heeger model supplemented by long-range Coulomb interactions, taking account of the formation of excitons and the influence of disorder. In the calculated third-harmonic generation spectrum, on the high energy side of the main peak (due to the lowest singlet exciton) a second peak (due to the three-photon resonance to the electron-hole continuum) is found that is strong enough to remain significant even in the presence of disorder. The results are in good agreement with experiments in polydiacetylene and polythiophene.

ISSN:1058-725X    

DOI:10.1080/10587259208046867

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The third order optical nonlinearity, x(3), of two polymers consisting of nickel dithiolene guest molecules in a polymethylmethacrylate host have been measured. The optical nonlinearity was measured by degenerate four wave mixing experiments at a wavelength of 1.06 μm using 100 ps laser pulses. χ(3)coefficients of up to 10−17m2/V2were observed corresponding to nonlinear refractive index, n2, of up to 10−8cm2/KW with a damaged threshold > 1GW/cm2.

ISSN:1058-725X    

DOI:10.1080/10587259208046868

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We report on nonlinear optical properties of a new class of efficient nonlinear optical compounds built of trihalides interacting weakly with donor type molecules. Adducts of iodoform with sulphur (CHI3· 3S8) and quinoline (CHI3· 3C9H7N) exhibit sizeable electrooptic effects and second harmonic generation comparable to POM and better than urea. Angle-tuned phase matching of type I and II has been observed for both compounds. The comparison between the electrooptic effect and the second harmonic generation suggests that the electrooptic effect is mostly electronic in origin. The atomic force microscope was used to record the molecular structure on free-standing iodoform-sulphur crystal plates. The intermolecular spacings on the crystal surface correspond remarkably closely with those in the bulk.

ISSN:1058-725X    

DOI:10.1080/10587259208046869

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A variety of optically nonlinear tolan chromophores and epoxy based polymers containing them have been prepared and studied. The molecular hyperpolarizabilities of the dye chromophores have been measured by the EFISH technique while the polymers containing them have been examined by calorimetry, X-ray diffraction, dielectric spectroscopy as well as the appropriate linear and nonlinear optical techniques. Novel liquid crystalline behavior has been encountered in some of these monomers and polymers.

ISSN:1058-725X    

DOI:10.1080/10587259208046870

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We have measured a spectrum of third-order nonlinear optical susceptibility |x(3)(-3ω;ω,ω,ω)| of σ-conjugated polysilane, poly(di-n-hexylsilane) (PDHS), by means of third-harmonic generation (THG) measurement, in the fundamental photon energy region from 0.56 eV to 2.15 eV. The obtained | x(3)(3ω; ω, ω, ω)| spectrum exhibits three peaks. These peaks are interpreted as the multi-photon resonance enhancement to the one-dimensional exciton states. This exciton model can be applied also to the nonlinear optical response of other conjugated polymers.

ISSN:1058-725X    

DOI:10.1080/10587259208046871

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Optical properties of densely doped organic optically nonlinear materials were investigated by means of optical absorption spectroscopy, optical harmonics generation, X-ray diffraction spectroscopy and pressure tuning spectroscopy. From the investigation of the absorption λmax, 2‐methyl‐4‐nitroaniline(MNA) in poly methyl methacrylate(PMMA) exhibited an intermediate character between the crystal and the MNA dissolved in the solvents, i.e., some type of “amorphous”, and in the regenerated cellulose(cellophane) almost the same character as the MNA crystal. These results were consistent with the X-ray diffraction analysis, the second and third harmonics generation and the pressure effect on the absorption λmax and fwhm.

ISSN:1058-725X    

DOI:10.1080/10587259208046872

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The third-order nonlinear optical susceptibility has been investigated for oriented thin films of halogen bridged platinum complexes. The | χ(3)(−3ω;ω,ω,ω) | spectrum associated with the third harmonic generation (THG) was measured by the Maker fringe method in the region of fundamental wavelength 0.6 μm∼1μm and 1.6μm∼2.2μ m. In the | χ | spectra, we found a peak structure at ω ∼ 1.8eV that is attributable to a two-photon resonance to the optically forbidden charge transfer exciton. The | χ(3)| value was in the order of 10−11esu that is comparable to the π-conjugated polymers. Common features of NL0 processes for the one-dimensional semiconductors are discussed.

ISSN:1058-725X    

DOI:10.1080/10587259208046873

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Preparation of new polydiacetylenes by solid-state polymerization and their third-order nonlinear optical susceptibilities are discussed.

ISSN:1058-725X    

DOI:10.1080/10587259208046874

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A series of meso-monosubstituted porphyrins and metalloporphyrins, MOEP-X (M = 2H or Zn; OEP = octaethylpor-phyrin; X = NO2, CN or CHO) and ZnTPP-N02(TPP = tetraphenyl-porphyrin), were synthesized and characterized. The effect of the substituents and metals on the dipole moment is discussed. A preliminary investigation of the nonlinear optical property is presented.

ISSN:1058-725X    

DOI:10.1080/10587259208046875

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Molecular orbitals and third‐order susceptibility for terephthal‐bis‐(4‐N,N-diethylamino aniline) are calculated. The electronic mechanism is explained approximately by a three level system. The effect of orbital shape upon the susceptibility is analyzed. It is found that molecular orbital distortion due to substituted nitrogen atoms, enhances the transition moment of 1Bu – 2Ag and contributes to the third‐order susceptibility.

ISSN:1058-725X    

DOI:10.1080/10587259208046876

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor