Crystal organic nonlinear optical materials

Figure 2. Tradeoffs between polymer and crystal organic nonlinear optical materials. EO refers to applications for electro-optic waveguide devices such as modulators and switches. SHG refers to applications for frequency doubling of moderate and low power laser sources. A + indicates favored, - indicates disfavored, 0 indicates neither favored nor disfavored, and x indicates not relevant.

Pintre, I. C. Serrano, J. L. Ros, M. B. Martinez-Perdiguero, J. Alonso, I. Ortega, J. Folcia, C. L. Etxebarria, J. Alicante, R. Villacampa, B. Bent-core liquid crystals in a route to efficient organic nonlinear optical materials. J. Mater. Chem. 2010, 20, 2965-2971. 

In the early days, optical nonlinearity of organic materials was measured usually with powder samples, mainly because it is very difficult to isolate organic compounds in the form of molecular crystals. In the case of centrosymmetric crystal lattices, macroscopic second-order nonlinear optical characteristics are not detected. Molecular crystals are organized assemblies of individual molecules held together by intermolecular forces. Their macroscopic nonlinear optical constants are estimated as the sum of the molecular polarizability of individual molecules. Thus, neglecting intermolecular interactions in the crystal, the nonlinear optical constant, dtlK, is expressed by... 

Organic compounds with delocalized jr-electron systems, e,g., jr-conjugated polymers, are considered to be candidates for third-order nonlinear optical materials. Among them, polydiacetylenes (PDAs) are an important class of conjugated polymers that has attracted investigators from many different fields (7,2). PDAs, which can be obtained as single crystals by topochemical solid-state polymerization (5), have been extensively studied since 1976 (4). PDAs show large third-order nonlinear optical susceptibilities (5) and ultrafast optical... 

Moreover, organic functionalization of a polymer chain can lead to improvement in the physical properties, such as thermal stability and mechanical strength of the resulting siloxanes (Figure 3.1). Appropriate substitution on the polysiloxane backbone can lead to diverse materials such as liquid crystals," crosslinking agents, conductive and electroluminescent polymers, nonlinear optical materials,and bactericides. ... 

Garito, A. F., and Singer, K. D., Organic crystals and polymers—a new class of nonlinear optical materials. Laser Focus, Feb., 59 (1982). 

J. Zyss, ed.. Molecular Nonlinear Optics Materials, Physics, and Devices, Academic Press, Inc., San Diego, Calif, 1994 and its predecessor volumes D. S. Chemla and J. Zyss, Nonlinear Optical Properties of Organic Molecules and Crystals, Vols. 1 and 2, Academic Press, Inc., San Diego, Calif, 1987. 

High Tc Superconductors and Organic Conductors Ferroelectrics and Dielectrics Chalcogenide Glasses and Sol-Gel Materials Nanostructured Materials Liquid Crystals, Display, and Laser Materials Conducting Polymers Nonlinear Optical Materials... 

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