Second-order nonlinear optical devices

Jen [2] prepared thermally reversibly electrooptic polymers, (V), via a Diels-Alder reaction, as illustrated below, that were used in second-order nonlinear optical devices. 

A method utilizing differential scanning calorimetry has been developed for quick and reproducible estimation of the thermal stability of nonlmear optical chromophores under consideration for incorporation into polymers for use in second-order nonlinear optical devices. The mediod which uses sealed glass ampoules has been used to compare a large number of chromophores and has been compared to electric field-induced second harmonic generation methods. 

L., and Cahill, R A., Second-order nonlinear optical devices in poled polymers, Proc. SPIE, 1147, 233-244 (1989). 

Fig. 1. Representative device configurations exploiting electrooptic second-order nonlinear optical materials are shown. Schematic representations are given for (a) a Mach-Zehnder interferometer, (b) a birefringent modulator, and (c) a directional coupler. In (b) the optical input to the birefringent modulator is polarized at 45 degrees and excites both transverse electric (TE) and transverse magnetic (TM) modes. The appHed voltage modulates the output polarization. Intensity modulation is achieved using polarizing components at the output.

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... 

Recent advances in optical technology have created great interest in the construction of second-order nonlinear optical (NLO) devices for frequency conversion and electrooptic modulation. Although inorganic substances such as LiNbO possess strong second-order NLO properties and... 

Clearly, a requirement for device quality second-order nonlinear optical materials is a noncentrosymmetric dipolar chromophore lattice. There are several ways by which such lattices have been achieved. With all methods, a force must... 

Several papers and patents deal with the preparation of pyrrole-, indole-, and carbazole-derived dyes for application in organic laser device production, coloring of textiles and other materials, photography, analytical chemistry and physiological and organ function monitoring. Sulfonyl-substituted 2-[4-(dialkylamino)phenyliminomethyl]pyrrole dyes have been prepared, for example, 50-53, and their ultraviolet-visible (UV-Vis) absorptions, second-order nonlinear optical properties, and thermal stabilities have been described <1999TL2157>. 

The poled polymer approach is state-of-the-art in terms of the application of polymers to electro-optic devices such as modulators and waveguides. Chromophore-bound polymers for second-order nonlinear optical applications with glass transition temperatures greater than 320°C have been reported (5). However, the electro-optic coefficients are modest, typically less than 10 pm/V at 1.3 im. Part of the poling problem is caused by electrical conductivity at high poling temperatures, which reduces the poling field, or worse, sometimes causes dielectric breakdown. 

Mao, S.S.H., Y. Ra, L. Guo, C. Zhang, L.R. Dalton, A. Chen, S. Gamer, and W.H. Steier. 1998. Progress towards device-quality second-order nonlinear optical materials 1. Influence of composition and processing conditions on nonlinearity. Temporal stability and optical loss. Chem Mater 10 146-155. 

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