Electrooptic coefficient

The birefringent (BR) modulator makes use of polarized light and tensorial nature of the electrooptic coefficient. For example, poled organic polymer films are characterized by two nonzero components for the electrooptic tensor and parallel and orthogonal to the poling direction,... 

For crystalline solids, comparative quantities for second harmonic generation and the linear electrooptic coefficient are given by Miller s delta and the polarization optic coefficient f. The quantity 6 is defined by the relation... 

Yu-Shan Li, K. Tada, T. Murai, T. Yuhara, Electrooptic Coefficient T33 in Proton-Exchanged z-Cut LiTaOs Waveguides, , Japan. J. Appl. Phys. 28, L263-L265 (1989). Yu.N. Korkishko, V.A. Fedorov, V.V. Nosikov, S.M. Kostritsldi and M.P. De MicheU The phase diagram of H Lii NhOs optical waveguides , Proc. SPIE 2997, 188-200 (1997). 

Comments on NLO and Electrooptic Coefficients. Typically, the Pockels effect is observed at relatively low frequencies (up to gigahertz) so that slower nonlinear polarization mechanisms, such as vibrational polarizations, can effectively contribute to the "r" coefficients. The tensor used traditionally by theorists to characterize the second-order nonlinear optical response is xijk Experimentalists use the coefficient dijk to describe second-order NLO effects. Usually the two are simply related by equation 31 (16) ... 

Electrooptic Measurements. The final characterization method to be discussed is the measurement of the electrooptic coefficient. The electrooptic effect is derived from... 

For the sake of illustration, the determination of the electrooptic coefficient for a uniaxial crystal is described below. Considering the nonlinear uniaxial medium of Figure 11, a D.C. electric field is applied in the z direction. The effect of the electric field is to modify the refractive index in the z direction by an amount proportional to the electric field, the modified ellipsoid is given as... 

Electrooptic coefficient measured for poled host-guest systems with the chromophore weight percentage in parentheses. 

Although the bulk SHG and electrooptic coefficients, d33 and r33, are frequently quoted in pm V-1, many NLO quantities (and most of those discussed in this chapter) are typically expressed in c.g.s. units. These are not usually stated explicitly, but esu is used to denote that the units are the appropriate electrostatic units for that quantity in the c.g.s. system. We have followed this practice in this chapter. Some important conversions from esu to SI units are given in Table 11.3. In addition, we have followed the practice of quoting 2PA cross-sections in Goeppert-Mayer (GM) units, which are named after the scientist who first predicted 2PA processes [204, 205], and defined as 1 GM = lO-50 cm4 s (photon)-1. In addition, readers should note that cross-sections are sometimes quoted in cm4 GW-1 cross-sections in these units can be converted to cm4 s (photon)-1 by multiplying by the photon energy. 

It follows from the definitions above that for measuring the electrooptic coefficients, one should measure the index variation due to the application of an electric field. Evanescent waves coupled by the ATR method to surface plasmons or to waveguide modes have been demonstrated as useful tools for measuring electrooptical properties of NLO Langmuir-Blodgett films and NLO polymers [81-85],... 

See Table 23. Indices of refraction were determined from waveguiding experiments. Electric field during poling. Electrooptic coefficient. 

The linear and nonlinear optical behaviors of poly-(1,6-heptadiyne)s containing NLO chromophores was summarized in Table 22. It was found that n of the copolymers gave higher values than that of poly-76 not bearing any chromophore while the values of Amax were similar to each other. This result clearly shows the effects of incorporation of chromophore into the polymer backbone. The values of electrooptic coefficients, r33, for poled film samples of poly-77 to poly-81 by using a simple reflection technique reported by Teng et al. was measured. Table 22 shows the measured electrooptic coefficients of polymer films at... 

The electrooptic coefficient can be related to the second order susceptibility by ... 

Banach MJ, Alexander MD Jr, Caracci S, Vaia RA. 1999. Enhancement of electrooptic coefficient of doped films through optimization of chromophore environment. Chem Mater 11 2554 2561. 

Agullo-Lopez, R, Cabrera, J.M., and Agullo-Rueda, F. (1994) Electrooptics Phenomena, Materials, and Applications, Academic Press, London. Gives a very detailed description of aU aspects of electrooptic materials. Two of the chapters cover applications. It also provides information about how electrooptic coefficients are determined experimentally. 

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