Linear electrooptic coefficient

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... 

Sugie, M., and Tada, K, Measurements of the linear electrooptic coefficients and analysis of the nonlinear susceptibilities in cubic GaAs and hexagonal CdS, Jpn. Appl. Phys., 15, 421 (1976). 

In poled polymers, the noncentrosymmetric alignment of NLO-active chromophores is achieved by electrically poling the material at the glass-rubber transition temperature. The alignment under these conditions is locked in by cording the sample with the field still apidiod. The linear electrooptical coefficient for a poled polymer is given by [458,459]... 

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... 

Lipscomb, G. F., Garito, A. F., and Narang, R. S., An exceptionally large linear electro-optic effect in the organic solid MNA, J. Chem. Phys., 75, 1509 (1981). Sigelle, M, and Hierle, R., Determination of the electrooptic coefficients of 3-methyl 4-nitropyridine 1-oxide by an interferometric phase-modulation technique, J. Appl. Phys., 52, 4199 (1981). 

Broussoux and Mkheron [17] reported electrooptic and elastooptic effects in stretched PVDF. The linear EO coefficients in PVDF were measured at room temperature and constant stress at the He-Ne laser wavelength. The refractive indices n, 1.444. A = 1.436, and n, 1.42S and electrooptk coefficients rn = 0.10 pmA, 0.21 pm/V were OKasured. The secondary electrooptic effect estimated for the longitudinal configuration was ZS% of the measured free electrooptic coefficient. The quadratic electrooptic coefficients at constant strain and stress were gu 0.02 m /C and ga s 0.01 m /C. ... 

As shown in previous sections of this chapter, when an external perturbation is applied to the polymer film (such as irradiation), the ATR guided modes shift their angular positions and the reflectivity is modulated (Fig. 31b). These angular shifts are very small in the case of electrooptic experiments they correspond to refractive index variations of the order of 10 . One has then to modulate the measuring electric field at a low frequency Q( = cos fit) and to detect the modulated signal with lock-in amplifiers. The lock-in signals detected at the modulation frequency and its second harmonic give, respectively, the linear (or Pockels) and the quadratic (or Kerr) electrooptic effects. The amplitude of the modulation of the thickness and the refractive indices is evaluated by a computer fit, and allows the determination of Pockels (r) and Kerr (s) coefficients (Eqs. 28) ... 

In Equation (14.7), the linear term vanishes and only the Kerr effect term survives. The electrooptic tensor for the Kerr effect varies with different molecular stmcture. For an isotropic Uquid, its quadratic electro-optic effect coefficients can be represented by the following matrix ... 

A sensitive approach for the analysis of molecular structures is the measurement of rotation time constants and optical anisotropy coefficients by relaxation electrooptical methods.The experimental procedure used for electrooptical investigations is relatively simple samples are subjected to electric field pulses, and the response due to field-induced alignment or field-induced reactions is recorded by spectrophotometric techniques. In the dichroism experiments, the absorbance of polarized light is measured under electric field pulses. The measured quantity, linear dichroism (LD), means that anisotropic absorption of plane or linearly polarized light has taken place. 

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