Multipolar engineering of molecules and materials for quadratic nonlinear optics

Abstract

The first generation of molecular engineering studies whereby a one-dimensional bipolar donor-acceptor conjugated system had served, since the early 1970s, as a quasi-exclusive template, had failed to take into account the tensorial dimension attached to the β quadratic hyperpolarizability tensor. We review here the outgoing second generation of molecular design studies based on three-dimensional multipolar charge transfer which reflects on enhanced values for all β ij k coefficients, then opening-up the possibility of polarizationindependent nonlinear interactions. This can be ensured by more isotropic crystalline lattices or statistical polymer-based orientational distribution out of reach for the cruder one-dimensional systems. A particular challenge which has in fact triggered this domain in the early 1990s to this day has been set by octupolar systems whereby the symmetryimposed cancellation of the dipole moment precludes the utilization of an electric field coupling scheme to orient molecules into a noncentrosymmetric order. We will review this new domain, encompassing both physical and chemical considerations, all the way from new molecular engineering techniques, with associated quantum modeling, to advanced characterization methods and macroscopic ordering schemes jointly aiming at promoting and exploiting the so far largely ignored tensorial dimension of nonlinear light-matter coupling schemes in molecules. To cite this article: I. Ledoux, J. Zyss, C. R. Physique 3 (2002) 407-427.  2002 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS molecular engineering / nonlinear optics / octupoles / multipoles / polymers / molecular crystals / dendrimers

Polymeric metal‐organic octupolar NLO materials: lithium(I) and sodium(I) 3,5‐dinitrobenzoates

“…In the absence of resonances (this is true in our case, considering the nearly colourless samples and the wavelengths of incident and second harmonic lights), the hyperpolarisability tensor can be decomposed into dipolar (β J=1 ) and octupolar (β J=3 ) spherical components [2,13]. In a purely octupolar environment (e.g.…”

“…However, unlike such molecules that must necessarily be rod-shaped, NLO chromophores can also be non-dipolar 2D or 3D molecules or species of octupolar symmetry -D 3h , D 3 , T d or D 2d [1][2][3][4]. Such chromophores, referred to octupolar NLO-phores or octupoles, possess advantages that can exploit the tensorial nature of β.…”

Morphology, Linear and Nonlinear Optical Response of Octopolar Chromophores Embedded in a Silica Sonogel Matrix

“…rodlike dipolar systems. Nevertheless, second-order ONL effects may also arise from some centrosymmetric molecular structures, such as octopolar compounds, which posses a zero overall dipole moment and liquid crystalline (LC) behavior in columnar phases [1][2][3]. The development of octopolar nonlinear optical materials suitable for several applications in optical, nonlinear optical and electro-optical devices is a topic of current interest among many research groups.…”

Unusual supramolecular assembly and nonlinear optical properties of l-histidinium hydrogen malate

“…The individual molecules organize themselves into supramolecular aggregates that have welldefined structures often resulting in unique chemical and physical properties [1][2][3][4][5]. For the past two decades, extensive efforts have been directed toward the design and synthesis of efficient chromophores, which can be incorporated into macroscopic assemblies such as polymers, to form materials exhibiting large nonlinear optical and electro-optic responses [6][7][8][9][10][11]. A successful example is the case of octupolar nonlinear materials pioneered by the group of Zyss et al [12] and Feuvrie et al [13] that have been successfully tailored and attempts for supramolecular associations between cationic and anionic octupolar derivatives have been made very recently.…”