Abstract. present the method for analyzing the anisotropy of acoustooptic figure of merit for optically uniaxial crystals and illustrate it on the example of crystalline paratellurite. This first part of the article deals with analysis of the isotropic acoustooptic interaction. The results of our calculations agree well with the experimental data known from the literature.

We have developed a method for the analysis of anisotropy of an acousto-optic figure of merit (AOFM), which is valid for the case of anisotropic diffraction in the trigonal crystals of the point symmetries 3m, 32, and 3¯m. The method is verified via the example of LiNbO₃ crystals. The relations for the effective elasto-optic coefficients and the AOFM are obtained for the three types of acousto-optic (AO) interactions peculiar for the anisotropic AO diffraction: the interaction of a so-called type VII with a quasi-longitudinal acoustic wave and the interactions of types VIII and IX with two quasi-transverse acoustic waves. The AO diffraction geometries providing maximal AOFM values have been determined for each of the mentioned interaction types. We have found that the maximum AOFM proper for LiNbO₃ is equal to 15.9×10^-15 s³/kg. This value is achieved at the type IX of AO interactions in the interaction plane rotated by 60.0 deg around the principal X axis with respect to the principal X-Z plane. The type VIII of AO interactions is characterized by a comparable AOFM (15.1×10^-15 s³/kg), which is realized in the Y-Z interaction plane. A close comparison of our results with the available experimental data demonstrates their fairly good agreement.

The influence of inhomogeneous fields on the optical properties of crystals is discussed on the basis of the phenomenological approach: we discuss here the results of birefringences in LiNbO3 crystals under the inhomogeneous mechanical strain (torsion) for various experimental configurations and the observation of optical activity under the torsional deformation in centrosymmetrical NaBi(MoO4)2 crystals. The possibility of application of the torsion-induced optical effects is also mentioned.

We suggest a new approach for analyzing spatial anisotropy of acoustooptic figure of merit (AOFM). The relations for the effective elastooptic coefficients and the AOFM are derived for all possible types of acoustooptic (AO) interactions in optically is otropic media, including non-solid-state and solid -state amorphous media, and crystals belonging to the cubic system. Our approach allows for finding the optimal geometries of AO interactions characterized by the highest AOFM for a given material. The analysis is carried out on the examples of cubic KBr and KAl(SO4)2×12H2O crystals which represent different subgroups of the cubic symmetry class. OCIS codes: 260.1180OCIS codes: 260. , 230.1040OCIS codes: 260. , 160.1050OCIS codes: 260. , 260.1960 http://dx.doi/org/10.1364/AO.99.099999 1.IntroductionAmong the parametric optical effects induced by external fields, such as electro-, magneto-, piezo-and acoustooptic (AO) ones [1,2], AO diffraction represents ma ybe the most frequently used effect. This phenomenon is utilized for deflecting and modulating of light, scanning of the optical beams, RF spectrum analyzing, Q-switching, etc. [3 -6]. It is well known that efficiency of the AO diffraction is d efined by the AO figure of merit (AOFM):where n , ef p and ρ denote respectively the optical refractive index, the effective elastooptic coefficient (EEC) and the density of an optical material, and v the velocity of the acoustic wave (AW). Although the 2 M parameter is scalar, it can reveal notable spatial anisotropy. This anisotropy is mainly influenced by the elastooptic tensor and the tensor of elastic stiffness coefficients, on the basis of which the AW velocities are determined. Anisotropy of the refractive indices contributes to the total spatial dependence of 2 M , too. Thus, the AO efficiency simulta neously depends on a number of constitutive coefficients of a given optical material. Searching for efficient materials for the AO diffraction is of a primary importance. Moreover, development of the methods for analyzing the anisotropy of AO efficiency for different geometries of AO interactions can solve a lot of materials science problems, since the anisotropy of the 2 M coefficient can yield in increasing AO efficiency for both well-known and new materials. As shown in our recent works [7,8], the anisotropy of AW velocities often plays a major role in the anisotropy of AOFM. In fact, it can result in extremely high 2 M coefficient, e.g., for one of the best AO materials, TeO2 crystal [9,10].It is obvious that the EEC and its anisotropy also contribute significantly to the AO efficiency. In particular, this contribution can become notable for the media where the AW velocities are almost isotropic (see, e.g., [11]). Unfortunately, no general method for analyzing the anisotropy of AO efficiency has been developed up to now. To our best knowledge, there have been a few relevant attempts, which are based on the anisotropies of the EEC [12] and the AW velocities [2]. A combined method has been suggested in Ref. [13,1...

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We have developed the approach for analyzing anisotropy of acoustooptic figure of merit (AOFM) for lithium niobate crystals in the case of isotropic acoustooptic (AO) diffraction.The working relations for the effective elastooptic coefficients and the AOFM have been derived. We have found that, under the conditions of isotropic AO diffraction, the maximum AOFM value for LiNbO 3 is equal to 11.62×10

Abstract. We present the developed method for analyzing the anisotropy of acoustooptic figure of merit (AOFM) for the case of anisotropic diffraction in optically uniaxial crystals, and we illustrate it on the example of crystalline paratellurite. We demonstrate that nine types of acoustooptic (AO) interactions can be implemented in general, six types for the isotropic interactions and three for the anisotropic ones. When the AO diffraction is collinear, the angular dependence of the AOFM is characterized by narrow peaks or dips. In the case of anisotropic diffraction, the maximum AOFMs for the paratellurite crystals are reached for the AO interactions of the type VIII with the acoustic wave QT 1 propagated along the [110]

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