Molecular crystals, nonlinear optical properties

Liquid crystal polymers are also used in electrooptic displays. Side-chain polymers are quite suitable for this purpose, but usually involve much larger elastic and viscous constants, which slow the response of the device (33). The chiral smectic C phase is perhaps best suited for a polymer field effect device. The abiHty to attach dichroic or fluorescent dyes as a proportion of the side groups opens the door to appHcations not easily achieved with low molecular weight Hquid crystals. Polymers with smectic phases have also been used to create laser writable devices (30). The laser can address areas a few micrometers wide, changing a clear state to a strong scattering state or vice versa. Future uses of Hquid crystal polymers may include data storage devices. Polymers with nonlinear optical properties may also become important for device appHcations. 

Molecular Optics Nonlinear Optical Properties of Organic and Polymeric Crystals... 

Except through the study of linear and nonlinear optical properties of molecular crystals, methods to determine the nature of / require evaluation of appropriate characteristics of... 

Several organometallic moieties serving as acceptors and donors have been evaluated. Molecular crystals of stilbenes have been shown to be unusually active in second harmonic generation. The linear and nonlinear optical properties of 3-methyl-4-methoxy-4 -nitro-stilbene (MMONS) single crystals will be presented. 

In this paper, we make use of molecular modelling techniques, particularly the AMI semiempirical molecular orbital method, to study the intermolecular interactions that are important for determining the manner in which crystal formation takes place. We are particularly inter ested in compounds that can potentially exhibit nonlinear optical properties. The calculational techniques are directed towards providing insight into the manner in which the desired nonlinear optical properties can be op timized in the macromolecular crystal state.(1)... 

Polymers and an Unusual Molecular Crystal with Nonlinear Optical Properties... 

F Wudl, P-M Allemand, G Srdanov, Z Ni, D McBranch. Polymers and an unusual molecular crystal with nonlinear optical properties. In SR Marder, J Sohn, GD Stucky, eds. Materials for Nonlinear Optics Chemical Perspectives. ACS Symposium Series 455 683, 1991. 

Zyss, J., and Chemla, D. S. (1987). Quadratic nonlinear optics and optimisation of the second-order nonlinear optical response of molecular crystals. In Nonlinear Optical Properties of Organic Molecules and Crystals. (Chemla D. S., Zyss J., eds.),. Academic Press, Boston. 

Dick B, Hochstrasser RM, Trommmsdorf HP (1987) In Chemla DS, Zyss J (eds). Resonant Molecular Optics Nonlinear Optical Properties of Organic Molecules and Crystals, vol 12. Academic, New York, p 159... 

With few exceptions, a useful nonlinear optical material will be in the solid phase for example, a single crystal or a poled polymer embedded in a film. Ironically, the quantum chemical calculations of nonlinear optical properties have for the most part been concerned with a single microscopic species. Much has been learned in this way about appropriate molecular construction, but the ultimate goal must be to investigate the nonlinear optical (NLO) properties in the solid phase. 

Zyss, J. Berthier. G. Nonlinear optical properties of organic crystals with hydrogen-bonded molecular units The case of urea. J. Chem. Phys. 1982. 77 (7). 3635. 

Chemla DS. Nonlinear Optical Properties of Organic Molecules and Crystals. Elsevier, 2012. Kanis DR, Ratner MA, Marks TJ. Design and construction of molecular assemblies with large second-order optical nonlinearities. Quantum chemical aspects. Chem Rev. 1994 94(l) 195-242. http //dx.doi.org/10.1021/ct00025a007. 

Optical Properties of PDA Microcrystals of Different Sizes. The effect of average molecular weight on the functions of PDA microcrystals is expected to be important from the point of view that the electronic and nonlinear optical properties of quantum-wire and quantum-dot structures differ significantly from those of bulk crystals. An enhancement of several orders of magnitude in third-order optical nonlinearities has been predicted in the case of quantized microaystallites. 

Wudl, E, Allemand, P.-M., Srdanov, G., Ni, Z., and McBranch, D., Polymers and unusual molecular crystal with nonlinear optical properties, in Materials for Nonlinear Optics Chemical Perspectives, (S. R. Marder, J. E. Sohn, and G. D. Stucky, eds.). Am. Chem. Soc. Symp. Sen, 455(ACS), American Chemical Society, Washington, DC, 1991, pp. 683-686. 

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. 

F. Wudl, P. M. Allemand, G. Srdanov, Z. Ni, and D. McBranch, Polymers and an Unusual Molecular Crystal with Nonlinear Optical Properties (ACS Symposium Series, 455), American Chemical Society, Washington, D. C., 1991, p. 683. 

Laser-induced molecular reorientation is a common cause of optical nonlinearity in a fluid medium. In this respect, liquid crystals are often strongly nonlinear because of their large molecular anisotropy and strong correlation between molecules. The nonlinear optical properties of liquid crystals in the isotropic phase have already been studied quite extensively by a number of researchers in the past decade, This is, however, not true for liquid crystals in the mesophases. 

The liquid crystal mesophases provide various opportunities for thermal reorientation for instance, heating alters the pitch of cholesteric helices. Reference 14 considered nonlinear optical properties of C smectics associated with changes in the molecular orientation angle during heating. In this section we show that thermal orientation effects are also present in nonuniformly oriented nematics. 

Linear and nonlinear optical properties of liquid crystals in their mesophases have been studied in several contexts, in both fundamental and application-oriented pursuits. In the context of nonlinear optical processes, they have recently received considerable renewed interests as a result of the newly discovered extraordinarily large optical nonlinearity due to the laser-induced molecular reorientation, and a renewed effort explicitly at the large thermal index effect in liquid crystals. In the last few years, several groups [2]-[10] have looked at the optical nonlinearity in the mesophases of liquid crystals and the associated nonlinear processes. A brief review of some of these nonlinear optical processes and the fundamental mechanisms in both the liquid crystal and the isotropic phases has recently appeared [1]. In this paper, therefore, we will concentrate only on optical wave mixing processes that are relevant to this Special Issue. 

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