ABSTRACTA two-level expression of the second-order hyperpolarizability (y) is proposed, and shown... more 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 fol...
Nonlinear Optical Effects in Organic Polymers, 1989
The Langmuir-Blodgett (L-B) technique is well known as a method of building-up ordered arrays of ... more The Langmuir-Blodgett (L-B) technique is well known as a method of building-up ordered arrays of organic molecules, and especially as a means of imposing a noncentrosymmetric structure from molecules that crystallize in a centrosymmetric space group(1–3). L-B films for use in quadratic nonlinear optics can be ordered in a statistically noncentrosymmetric lattice. The method involves the compression of a mono-layer of the organic molecule, spread on top of a water surface, into a two-dimensional solid, followed by the repeated dipping of the substrate to be coated into and out of the subphase. Monolayers may be deposited onto the substrate both on immersion and withdrawal, resulting in a centrosymmetric arrangement of layers (Y-type deposition), or just on immersion (X-type) or withdrawal (Z-type), in which case a noncentrosymmetric structure should be obtained. However, this kind of samples is not very stable and tends to relax towards disordered structures. An alternative method is the successive deposition of alternate layers ABAB… where A and B are two different molecular species stacked following a Y-type structure, the hydrophobic chain being grafted onto the acceptor group of the first species A and onto the donor group of the second species B (4,5). The quadratic nonlinear response, resulting from the addition of the individual nonlinearities of each moiety, is quite large, with the additional advantage of a high degree of order and a good stability of the multilayers.
Unconventional Optical Elements for Information Storage, Processing and Communications, 2000
Engineering of new nonlinear materials, structures and devices with enhanced figures of merit has... more Engineering of new nonlinear materials, structures and devices with enhanced figures of merit has acted over the two last decades as a major driving force in optics: electrooptic polymers have emerged in this context as a sound basis for a currently maturing integrated optics technology with a variety of industrial applications at stake. We report here on a major turning point in this field whereby nonlinear optical phenomena, while remaining a major functional end-goal, are being furthermore implemented in the elaboration process itself. Coherent multiphoton processes appear indeed as unique tools to pattern linear and nonlinear structures to a sophistication level out of the reach of earlier technologies. We will review the basic physical phenomena involved which mainly pertain to quantum interferences between multiphoton excitation pathways in photosensitive media. Multipolar nonlinear patterns reflecting the multipolar symmetry of controllable polarization states of the coherent writing beams can be permanently or imprinted on a variety of substrates from films to waveguides, or gratings.
We report the experimental demonstration of spectral encoding of the polarization state of light ... more We report the experimental demonstration of spectral encoding of the polarization state of light by use of multiplexed distributed-feedback lasers in a dye-doped organic thin film by exploiting the pump polarization selectivity of the superimposed resonators. Measurement of the Stokes parameters of the pump light without a priori knowledge of the lasing properties of the structure is discussed.
Journal of Nonlinear Optical Physics & Materials, 1998
Organic materials for quadratic nonlinear optics generally follow the basic pattern of strongly d... more 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 pola...
Previous research toward more efficient nonlinear optical organic crystals has aimed at increasin... more Previous research toward more efficient nonlinear optical organic crystals has aimed at increasing the first‐order hyperpolarizabilitiy of individual molecular units. We show that the general features derived from these studies (high conjugation, charge transfer, and molecular asymmetry) ...
ABSTRACTA two-level expression of the second-order hyperpolarizability (y) is proposed, and shown... more 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 fol...
Nonlinear Optical Effects in Organic Polymers, 1989
The Langmuir-Blodgett (L-B) technique is well known as a method of building-up ordered arrays of ... more The Langmuir-Blodgett (L-B) technique is well known as a method of building-up ordered arrays of organic molecules, and especially as a means of imposing a noncentrosymmetric structure from molecules that crystallize in a centrosymmetric space group(1–3). L-B films for use in quadratic nonlinear optics can be ordered in a statistically noncentrosymmetric lattice. The method involves the compression of a mono-layer of the organic molecule, spread on top of a water surface, into a two-dimensional solid, followed by the repeated dipping of the substrate to be coated into and out of the subphase. Monolayers may be deposited onto the substrate both on immersion and withdrawal, resulting in a centrosymmetric arrangement of layers (Y-type deposition), or just on immersion (X-type) or withdrawal (Z-type), in which case a noncentrosymmetric structure should be obtained. However, this kind of samples is not very stable and tends to relax towards disordered structures. An alternative method is the successive deposition of alternate layers ABAB… where A and B are two different molecular species stacked following a Y-type structure, the hydrophobic chain being grafted onto the acceptor group of the first species A and onto the donor group of the second species B (4,5). The quadratic nonlinear response, resulting from the addition of the individual nonlinearities of each moiety, is quite large, with the additional advantage of a high degree of order and a good stability of the multilayers.
Unconventional Optical Elements for Information Storage, Processing and Communications, 2000
Engineering of new nonlinear materials, structures and devices with enhanced figures of merit has... more Engineering of new nonlinear materials, structures and devices with enhanced figures of merit has acted over the two last decades as a major driving force in optics: electrooptic polymers have emerged in this context as a sound basis for a currently maturing integrated optics technology with a variety of industrial applications at stake. We report here on a major turning point in this field whereby nonlinear optical phenomena, while remaining a major functional end-goal, are being furthermore implemented in the elaboration process itself. Coherent multiphoton processes appear indeed as unique tools to pattern linear and nonlinear structures to a sophistication level out of the reach of earlier technologies. We will review the basic physical phenomena involved which mainly pertain to quantum interferences between multiphoton excitation pathways in photosensitive media. Multipolar nonlinear patterns reflecting the multipolar symmetry of controllable polarization states of the coherent writing beams can be permanently or imprinted on a variety of substrates from films to waveguides, or gratings.
We report the experimental demonstration of spectral encoding of the polarization state of light ... more We report the experimental demonstration of spectral encoding of the polarization state of light by use of multiplexed distributed-feedback lasers in a dye-doped organic thin film by exploiting the pump polarization selectivity of the superimposed resonators. Measurement of the Stokes parameters of the pump light without a priori knowledge of the lasing properties of the structure is discussed.
Journal of Nonlinear Optical Physics & Materials, 1998
Organic materials for quadratic nonlinear optics generally follow the basic pattern of strongly d... more 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 pola...
Previous research toward more efficient nonlinear optical organic crystals has aimed at increasin... more Previous research toward more efficient nonlinear optical organic crystals has aimed at increasing the first‐order hyperpolarizabilitiy of individual molecular units. We show that the general features derived from these studies (high conjugation, charge transfer, and molecular asymmetry) ...
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Papers by J. Zyss