A recently proposed technique representing a combination of digital imaging laser interferometry with a classical four-point bending method is applied to a canonical nonlinear optical crystal, LiNbO₃, to precisely determine a full matrix of its piezo-optic coefficients (POCs). The contribution of a secondary piezo-optic effect to the POCs is investigated experimentally and analyzed theoretically. Based on the POCs thus obtained, a full matrix of strain-optic coefficients (SOCs) is calculated and the appropriate errors are estimated. A comparison of our experimental errors for the POCs and SOCs with the known reference data allows us to claim the present technique as the most precise.

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.

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We analyze polarization singularities of optical beams that propagate through crystals possessing structural dislocations. We show that screw dislocations of crystalline structure can lead to the appearance of purely screw-type dislocations of light wavefronts. This can happen only in crystals that belong to trigonal and cubic systems. These polarization singularities will give rise to optical vortices with the topological charge equal to ±1, whenever a crystal sample is placed between crossed circular polarizers. We have also found that edge dislocations present in the cubic and trigonal crystals, with the Burgers vector perpendicular to the three-fold symmetry axes, can impose mixed screw-edge dislocations in the wavefronts of optical beams and generate singly charged optical vortices. The results of our analysis can be applied for detecting and identifying dislocations of different types available in crystals.

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...