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Knowledge of the absolute value of the second order nonlinear optical coefficient of materials plays a key role in assessing the performance. The second harmonic (SH) wave is employed to measure accurately the second order nonlinear coefficient (d36) of the narrow band gap semiconductor, mercury cadmium telluride (MCT).

Research was conducted to examine the refractive indices of the optically nonlinear organic crystal (S)-3-methyl-5-nitro-N-(1-phenylethyl)-2-pyridinamine. The refractive indices were measured from 480 to 660 nm and fitted to four-parameter Sellmeier equations with an accuracy of +/-3 x 1/10 to the 3rd power to +/-5 x 1/10 to the 3rd power. The values of the n(sub x), n(sub y) and n(sub z) refractive indices at 532 nm were found from the Sellmeier equations to be 1.690, 1.901 and 1.725, respectively.

The linear electro-optic effect in single crystals of 4-aminobenzphenone (ABP) is reported together with calibration data on LiNb[O.sub.3]. For ABP the linear electro-optic coefficients [r.sub.22] and [r.sub.32] at 488 nm were found to be 2.12 and 5.05 pm/V, respectively, with the corresponding reduced half-wave voltages being 49.4 [+ or -] 0.1 and 9.3 [+ or -] 0.1 kV. For LiNb[O.sub.3] the half-wave voltage was found to be 4.0 [+ or -] 0.1 kV at 632.8 nm and 2.4 [+ or -] 0.1 kV at 488 nm. Key words: Electro-optic, half-wave voltage, organic crystal.

A more accurate method of obtaining the refractive indices of anisotropic prisms is introduced. Designed for prisms that undergo light polarization orthogonal to a dielectric prism axis, it does not require the orientation of the dielectric axes within a prism. It was developed on prisms made of 4-amino-benzophenone crystals characterized by low defect levels. The fitting of the linear refractive indices of ABP to Sellmeier equations and their verification via external angle of incidence observations is also discussed.

Measurements of linear electro-optic effect in 2-alpha-methylbenzyl-5-nitropyridine show that there is variation in the linear electro-optic effect with respect to the wavelength of incident light. Values of 2.1, 2.8, and 6.0 kilovolts at 488, 514.5 and 632.8 nanometers are exhibited by the methylbenzylamino compound as half voltages. The measurements also enable the variation of birefringence of the compound.

Flash diffusivity method is used to measure the thermal diffusivities of high quality alpha-methylbenzylamino-5 nitropyridine single crystals in different directions. From the various values of thermal diffusivity, specific heat and density data, the complete thermal conductivity tensor at temperatures of 295, 323 and 349 Kelvin are obtained. The Heckman method was used for the evaluation of the thermal diffusivities from temperature time response characteristics by using the least square methods. The value obtained for the thermal conductivity anisotropy is large for these materials.

The linear and nonlinear optical properties of 4-nitro-4'-methylbenzylidene aniline (NMBA) organic material are studied. Large single NMBA crystals are grown by temperature lowering of a seeded supersaturated ethyl acetate solution. The crystals are then subjected to a series of experimental and theoretical analyses. Results reveal that both angle and wavelength noncritical phase matching are possible with the NMBA crystals.

The linear electro-optic effect in 4-nitro-4-methylbenzylidene aniline single crystals was analyzed. The half-wave voltages were measured at 2.8, 1.3 and 1.1kV at 632.8, 514.5 and 488.0 nm. The results showed that the crystal features asignificant electro-optic effect. In addition, the birefringence was observed to be larger than that found in inorganic materials.

The variation of the linear electro-optic effect in (-)-2-(α-methylbenzylamino)-5-nitropyridine with the wavelength of the incident light at room temperature has been measured. The reduced half-wave voltages have been found to have the values 2.1, 2.8, and 6.0 kV at 488, 514.5, and 632.8 nm respectively and the corresponding values of the linear electro-optic coefficient have been evaluated. The interpretation of the results in terms of the structures of the molecule and the crystal is discussed. The thermal variation of the birefringence has also been investigated and the coefficient for the temperature variation of the refractive index difference is found to have the value (dΔn/dT)=9.3×10-5 K-1. [ABSTRACT FROM AUTHOR]

The organic crystal (S)-3-methyl-5-nitro-N-(1-phenylethyl)-2-pyridinamine that were previously identified by the powder technique as a promising nonlinear optical material, the large single crystals (3 * 3 * 2 cm(super 3)) of which is grown by temperature lowering of a seeded supersaturated solution in acetone is reported. Refined refractive indices are obtained from the predicted angles of incidence of the phase-matched second harmonic signals.