Light Beams' Focusing in Biaxial Ferroelectrics
GOMEL STATE UNIV (BELARUS)
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Among problems of modern optics the elaboration of the methods of formation and control by the space structure of light beams is of great importance. In the papers 1,2 it has been shown that the nonlens focusing and nondiffractional propagation of light, stipulated by the presence of concavity of wave vector surface, are possible near by optical axes of biaxial gyrotropic crystals. The application of external electric field leads to strengthening of concavity and then, increasing of focusing effect for slow waves near binormals 3. But conducted consideration was limited by the case of the most symmetrical biaxial crystal, namely, orthorhombic one. At the same time many widely used gyrotropic biaxial crystals have lower symmetry. For example, their symmetry is of 2 or m class. Its description is very complex, but at the same time is of essential interest in the connection with enlargement of possibilities of controlling by parameters of optical radiation. It is known that the big electrooptic effect takes place in ferroelectrics which have orientational spontaneous polarization in definite temperature range in the absence of external electric field. Characteristic peculiarity of given media is strong temperature dependence of optical and electrooptic properties which may be used for control by the focusing of optical radiation. The aim of the paper is investigation of influence of electric and temperature fields on focusing properties of the lens created on the base of lower symmetrical ferroelectric crystal of 2 class.
- Electrooptical and Optoelectronic Devices
- Electricity and Magnetism