Nonlinear optical materials applications

Due to the limited number of well-defined polygermanes that have been prepared and made available, few demonstrated applications have appeared. However, polygermanes have possible applications as photocondustors, photoresists, and nonlinear optical materials. Applications should be pursued. 

Most of the envisioned practical applications for nonlinear optical materials would require solid materials. Unfortunately, only gas-phase calculations have been developed to a reliable level. Most often, the relationship between gas-phase and condensed-phase behavior for a particular class of compounds is determined experimentally. Theoretical calculations for the gas phase are then scaled accordingly. 

Applications Involving Nonlinear Index Phenomena. The index of refraction, n, can be expressed for nonlinear optical materials as... 

Cycloaddition reactions with the Si(lOO) surface have been investigated for the purpose of designing microelectronics, nonlinear optical materials, sensors, and biologically active surfaces. The features of the [2+2] cycloadditions characteristic of the reactions in the pseudoexcitation band [133] predicts that [2+2] cycloadditions of electron-donating alkenes with Si(100)-2 x 1 surface could proceed with retention of configurations, in agreement with the observation [134]. Such stereospecific functionalizations of surfaces are of potential use for specific applications. 

This manuscript describes the dendritic macromolecules for optical and optoelectronic apph-cations, particularly stimulated emission, laser emission, and nonlinear optics. Dendrimers have been designed and synthesized for these applications based on simple concepts. A coreshell structure, through the encapsulation of active imits by dendritic branches, or a cone-shaped structure, through the step-by-step reactions of active imits, can provide particular benefits for the optical high-gain media and nonlinear optical materials. It also described experimental results that support the methods presented for designing and fabricating functionalized dendrimers for optoelectronic applications, and theoretical results that reveal the intermolecular electronic effect of the dendritic structure. 

Polymethyl(methacrylate) doped with 4-substituted 3-arylsydnones provide a promising class of nonlinear optical materials with various potential applications <2007SM142>. 

The coordination chemistry of the trichalcogenophosphonates is very undeveloped when compared to the analogous metal organophosphonates (RP032), which have been extensively studied owing to their potential and practical applications as ion exchangers, sorbents, sensors, proton conductors, nonlinear optical materials, photochemically active materials, catalysts and hosts for the intercalation of a broad spectrum of guests.145... 

Second-order nonlinear optics (NLO) has several applications in the field of optoelectronics.11 Several of these nonlinear processes are straightforward to experimentally demonstrate but their application in devices has been hampered by the lack of appropriate materials. Necessary requirements for second-order nonlinear optical materials include the absence of centrosymmetry, stability (thermal and mechanical), low optical loss, and large and fast nonlinearities.8... 

The purity and stability of three dichlorotriazine dyes applied in nonlinear optical materials was checked by RP-HPLC. The chemical structures of the dyes are shown in Fig. 3.131. Analyses were realized in an ODS column (250 X 4.6 mm i.d. particle size 5 jtim) using gradient elution. Aqueous ammonium acetate (50 mM) and methanol were solvents A and B, respectively. The detection wavelength depended on the absorption maxima of the dye. Chromatograms illustrating the decomposition of dyes under alkaline conditions are depicted in Fig. 3.132. It was established that the application of RP-F1PLC for the study of the purity and stability of dyes may facilitate their use in nonlinear optical materials. [179],... 

If the mesogens are pendant to the polymer backbone, materials are obtained with special magnetic, electrical and optical properties. They provide for nonlinear optics (NLOs) applications in numerous optoelectronic elements. 

Finally, the combination of dendrimers and organometallic entities as fundamental building blocks affords an opportunity to construct an infinite variety of organometallic starburst polymeric superstructures of nanoscopic, microscopic, and even macroscopic dimensions. These may represent a promising class of organometallic materials due to their specific properties, and potential applications as magnetic ceramic precursors, nonlinear optical materials, and liquid crystal devices in nanoscale technology. 

The cadmium chalcogenide semiconductors (qv) have found numerous applications ranging from rectifiers to photoconductive detectors in smoke alarms. Many Cd compounds, eg, sulfide, tungstate, selenide, telluride, and oxide, are used as phosphors in luminescent screens and scintillation counters. Glass colored with cadmium sulfoselenides is used as a color filter in spectroscopy and has recendy attracted attention as a third-order, nonlinear optical switching material (see NONLINEAR OPTICAL MATERIALS). Dialkylcadmium compounds are polymerization catalysts for production of poly (vinyl chloride) (PVC), poly(vinyl acetate) (PVA), and poly(methyl methacrylate) (PMMA). Mixed with TiCl4, they catalyze the polymerization of ethylene and propylene. 

Polysilane high polymers possessing fully saturated all-silicon backbone have attracted remarkable attention recently because of their unique optoelectronic properties and their importance in possible applications as photoresists, photoconductors, polymerization initiators, nonlinear optical materials etc. A number of review articles have been published on this topic4-9. The studies in this field have stimulated both experimental and theoretical chemists to elaborate on understanding the excited state nature of polysilanes and oligosilanes and of their mechanistic photochemistry. 

Applications of Organic Second-Order 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.

This investigation shows that an organized assembly ranging from isolated molecules to expanded structures stabilized inside a sodalite host matrix (Figure 1) can be readily fabricated out of a material that is normally a I-VII semiconductor. The (8-2n)Na,2nAg,2X-SOD sodalites might find applications as electronically tunable nonlinear optical materials (see later). 

As a conducting polymer, polyaniline has many electronics-related applications, such as rechargeable batteries (Tsutsumi et al. 1995), multilayer heterostructure light-emitting diode devices (Onoda Yoshino 1995), biosensors (Bartlett Whitaker 1987), elec-trochromic windows (Nguyen Dao 1989), and nonlinear optical materials (Papacostadi-nou Theophilou 1991). Polyaniline may be prepared from aniline by both electrochemi-... 

For the practical application of second-order NLO materials, not only a high hyperpolarizability but also good thermal stability is required. Heteroaryl diazo chromophores could also act as organic second-order nonlinear optical materials suitable for applications such as second... 

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