The developed technology involves:
1) measuring all existing components of electrical, piezoelectric, elastic, and nonlinear optical tensors and related effects (e.g., piezoelectric or elastic) in the studied crystalline materials (for this purpose, we have the necessary experimental base and developed methods for corresponding measurements for crystals of all symmetry classes);
2) construction of indicative or extreme surfaces for the studied effects as a single effective means of geometric representation of 3rd and higher-order tensors and spatial distributions of parameters characterizing the magnitude of the effect, and on this basis, conducting a 3D analysis of the spatial anisotropy of the corresponding effect (for this purpose, software has been developed to construct a three-dimensional image of such surfaces);
3) search for the global maximum of the studied effect and setting the corresponding geometry of the sample with the largest value of the electro-, piezo-, acousto- or nonlinear optical effect (also implemented on the basis of special software developed by us);
4) determining the increase in efficiency and stability of the studied crystalline material when used at parameter values corresponding to the global maximum point of the studied effect.
The proposed technology makes it possible to significantly increase the efficiency of implementation and stability of use of new or existing crystalline materials as working elements of solid-state optoelectronic devices operating on the principles of electrical, piezoelectric, acoustic, or nonlinear optical modulation or conversion of laser radiation. In addition, the use of crystalline materials at the point of maximum effect also guarantees a significant increase in the stability of the studied working parameter of the sample, and thus an increase in the stability of the technical characteristics of the corresponding device.
For many of the crystals we studied, it was discovered for the first time that the directions of the electric field, uniaxial pressure, polarization, and propagation of light and acoustic waves, which provide the highest electrical, piezoelectric, acoustic, or nonlinear optical parameters of crystalline materials, generally do not coincide with the main crystal physical axes. Thus, for the most effective geometry corresponding to the global maximum of the piezo-optical effect with angular coordinates Θ=42°, φ=30 ° and Θ=49°, φ=30°, an almost 5- and 4-fold increase in efficiency was obtained in piezo-optical transducers of lithium niobate and beta barium borate crystals, respectively. Similarly, for lithium niobate crystals with indirect cuts (Θ=54°, φ=90°), the maximum electrically induced path difference is almost 3 times greater, and the extreme value of the acousto-optical quality parameter for isotropic light diffraction is 2.4 times greater (for Θ=60°, φ=7°) compared to the corresponding parameters for the standard geometry of straight cuts of these crystals. This makes it possible to increase the efficiency of lithium niobate crystals as working elements of laser radiation control devices by the same amount.
Even in cases where a crystal with straight cuts is optimal in terms of ensuring maximum effect (for example, the electro-optical effect in a KDP crystal), the use of the presented technology is advisable, since it allows the optimality of such a configuration to be unequivocally established.