Polymer 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.

Polysilanes are cr-conjugated polymers composed of Si-Si skeletons and organic pendant groups. They are insulators with filled intramolecular valence bands and empty intramolecular conduction bands. However, because of strong cr conjugation, they have rather narrow band gaps of less than 4 eV [24,25] and are converted to conductors by photoexcitation or by doping electron donors or acceptors. Recently they have attracted much attention because of their potential utility as one-dimensional conductors, nonlinear optical materials, and electroluminescent materials [26-28]. 

The reader is also referred to other literature for a more comprehensive introduction to various aspects of optical nonlinearity and for more in-depth reviews of certain topics than can be covered in this review [2,3,5,24-87]. It is also suggested that the reader use these cited reviews to access literature not cited here. The literature on the topic of organic electro-optic materials now stands at many thousands of papers. It is unrealistic to attempt to even cite this entire body of literature here let alone discuss in depth all of the salient features of research into organic electro-optic materials. It is hoped that a readable overview of poled polymer electro-optic materials is provided in the following sections and that insight is provided both into the technological potential and problems associated with these materials. 

Williams, David J., and American Chemical Society Division of Polymer Chemistry. Nonlinear Optical Properties of Organic and Polymeric Materials. ACS Symposium Series no. 233. Washington, D.C. American Chemical Society, 1983. 

Polymer functionalization aims at imparting new properties (e.g. chemical, biophysical, physicochemical or optoelectronic) to materials. Functional polymers have been developed for a wide range of diverse applications. These include organic catalysis (support catalysts), medicine (red-blood-cell substitutes), optoelectronics (conducting polymers, magnetic polymers and polymers for nonlinear optics), biomaterials, paints and varnishes, building materids, photographic materials as weU as lube and fuel additives. While it is not possible to enum ate all of the applications of functional polymers, some representative examples of functional polymers are listed below. 

Recent development of organic nonlinear optical (NLO) polymers has focused on the fabrication of thermally stable NLO materials in which the second order nonlinearity... 

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. ... 

Recently, polymers show promising prospects as active constituents of optical and electronic devices, especially polymers for nonlinear optics and conducting polymers. In a remote future even organic ferromagnets and molecular electronics may become more than wishful thinking. For this reason several fundamental aspects of these materials are the subject of intensive research. In this paper we will review the present state of the art in these new fields of polymers for electronics and photonics. Special emphasis will be laid on recent results from our laboratories. 

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

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