Multipolar Symmetry Patterns in Molecular Nonlinear Optics

1998 ◽  
Vol 07 (03) ◽  
pp. 397-439 ◽  
Author(s):  
J. Zyss ◽  
S. Brasselet
Keyword(s):  
Nonlinear Optics ◽  
Three Dimensional ◽  
Molecular Engineering ◽  
Quantum Model ◽  
One Dimensional ◽  
Irreducible Components ◽  
Level Model ◽  
Linear Material ◽  
Two Level Model ◽  
Photoinduced Processes

Organic materials for quadratic nonlinear optics generally follow the basic pattern of strongly dipolar quasi one-dimensional intramolecular charge transfer molecules organized in macroscopic crystalline or statistical polar lattices. This restriction has been lifted by the introduction of the much broader class of multipolar materials whereby efficient two- and three-dimensional molecules can be fruitfully exploited in self assembled or externally engineered multipolar macroscopic structures. At the molecular level, polarized harmonic scattering permits to evaluate the invariant irreducible components of the molecular quadratic tensor. Its anisotropy and dispersion can be accounted for by a three-quantum model in agreement with linear spectroscopy on poled samples, whereas the validity of the two-level model is restricted to one-dimensional systems. Permanent macroscopic multipolar organization can be implemented by purely optical photoinduced processes. Adequate choice of the polarization of "write" beams permits to imprint any desired symmetry pattern onto the (non)linear material. Photonic engineering thus complements and considerably broadens the more traditional scope of molecular engineering.

RELATION BETWEEN QUANTUM AND GEOMETRIC DIMENSIONALITIES IN MOLECULAR NONLINEAR OPTICS: BEYOND THE TWO-LEVEL MODEL FOR ANISOTROPIC SYSTEMS

1996 ◽  
Vol 05 (04) ◽  
pp. 671-693 ◽  
Author(s):  
S. BRASSELET ◽  
J. ZYSS
Keyword(s):  
Excited States ◽  
Second Harmonic ◽  
Three Dimensional ◽  
Wavelength Dependence ◽  
Quantum Model ◽  
Substitution Pattern ◽  
Molecular Systems ◽  
Level Model ◽  
Anisotropic Systems ◽  
Two Level Model

The nonlinear optical susceptibilities of two- or three-dimensional molecular systems exhibit variable anisotropic features depending on their structure and substitution pattern. We show that appropriate geometric (e.g. tensorial) considerations combined with an n-level quantum model (n≥3) are able to account for such nonlinear anisotropy as rigorously defined in an invariant spherical formalism by extension of classical linear anisotropy. We call on two kinds of experiments to investigate these properties: firstly, variation of the incident polarization (VIP) in harmonic light scattering (HLS) experiments is being performed to sort out individual tensorial components of the quadratic hyperpolarizability β tensor; secondly, wavelength dependence studies in coherent second harmonic generation (SHG) from poled thin film media are shown at a preliminary stage to be able to designate those excited states responsible for the nonlinear anisotropy.

Quadratic and Cubic Nonlinearities in Solution of Intramolecular Charge Transfer Aromatic Molecules A Quantum Two-Level Approach

1987 ◽  
Vol 109 ◽  
Author(s):  
M. Barzoukas ◽  
P. Fremaux ◽  
D. Josse ◽  
F. Kajzar ◽  
J. Zyss
Keyword(s):  
Charge Transfer ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Third Harmonic ◽  
One Dimensional ◽  
Aromatic Molecules ◽  
Donor Acceptor ◽  
Level Model ◽  
Quadratic And Cubic Nonlinearities ◽  
Two Level Model

ABSTRACTA two-level expression of the second-order hyperpolarizability (y) is proposed, and shown to contain a negative charge transfer (CT) contribution. Frequency dispersed measurements of the quadratic and cubic susceptibility of N-(4-nitropheny1)-L-prolinol (NPP), N-(4-nitrophenyl)-N-methylaminoacetonitrile (NPAN) and 2-(N-prolinol)-5-nitropyridine (PNP) are reported. The electric field induced second-harmonic generation (EFISH) and third-harmonic generation (THG) techniques in solution are used. A two-level model dispersion of y as from THG measurements is shown to lead to a neglegible electronic contribution to the overall EFISH nonlinearity, as compared to the orientational contribution. The theoretical β-components of these molecules, obtained consistently by finite-field and perturbational approaches, clearly confirm that the β-tensor is one-dimensional along the donor-acceptor CT axis. The off resonance quadratic polarizabilities (β) of these molecules are sequenced as follows : β(NPP)> β(PNP)> β(NPAN). However this increased efficiency is obtained at the expense of the transparency range.

scholarly journals Асимметричная генерация в сверхизлучающем лазере с симметричным низкодобротным резонатором

2019 ◽  
Vol 53 (10) ◽  
pp. 1321
Author(s):  
Вл.В. Кочаровский ◽  
В.А. Кукушкин ◽  
С.В. Тарасов ◽  
Е.Р. Кочаровская ◽  
В.В. Кочаровский
Keyword(s):  
Active Medium ◽  
Population Inversion ◽  
Energy Levels ◽  
Active Centers ◽  
One Dimensional ◽  
Half Wavelength ◽  
Propagating Waves ◽  
Symmetric Cavity ◽  
Level Model ◽  
Two Level Model

On the basis of numerical solution to the Maxwell-Bloch equations within an one-dimensional two-level model of a superradiant laser with a symmetric cavity where a photon lifetime is less than an incoherent relaxation time of the optical dipole oscillations of active centers, we find that a spontaneous asymmetric generation of the counter-propagating waves is possible under a continuous homogeneous pumping of an active medium. We show that such a phenomenon of a symmetry breaking of the spatial profiles of the counter-propagating waves of an electromagnetic field as well as the polarization and population inversion of an active medium in the considered case of a weak inhomogeneous broadening of an operating transition is caused by an asymmetric half-wavelength nonlinear grating of the population inversion of the transition’s energy levels which is produced by these waves.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

scholarly journals Topological correlators and surface defects from equivariant cohomology

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Rodolfo Panerai ◽  
Antonio Pittelli ◽  
Konstantina Polydorou
Keyword(s):  
Quantum Mechanics ◽  
Equivariant Cohomology ◽  
Surface Defects ◽  
Star Product ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Dimensional System ◽  
The Novel ◽  
One Dimensional ◽  
Dual Quantum

Abstract We find a one-dimensional protected subsector of $$ \mathcal{N} $$ N = 4 matter theories on a general class of three-dimensional manifolds. By means of equivariant localization we identify a dual quantum mechanics computing BPS correlators of the original model in three dimensions. Specifically, applying the Atiyah-Bott-Berline-Vergne formula to the original action demonstrates that this localizes on a one-dimensional action with support on the fixed-point submanifold of suitable isometries. We first show that our approach reproduces previous results obtained on S3. Then, we apply it to the novel case of S2× S1 and show that the theory localizes on two noninteracting quantum mechanics with disjoint support. We prove that the BPS operators of such models are naturally associated with a noncom- mutative star product, while their correlation functions are essentially topological. Finally, we couple the three-dimensional theory to general $$ \mathcal{N} $$ N = (2, 2) surface defects and extend the localization computation to capture the full partition function and BPS correlators of the mixed-dimensional system.

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