Electro-optic and electro-gyration effects on light propagation in \bf \overline 4 2mpoint-group crystals

Abstract

Several nonlinear crystals that are used in laser and optical signal processing technologies belong to the {\overline 4}2m point group. This group exhibits as primary effects natural birefringence, optical activity, linear and quadratic electro-optic effects, and linear and quadratic electro-gyration effects, and, as secondary effects, photo-elasticity and piezo-gyrationviathe inverse piezo-electric phenomenon. The combination of these effects makes the study of light propagation a complicated task. In this work, the influence of each of these effects on light propagation is analytically reviewed, and suitable configurations for the light propagation and applied electric field directions are identified, which decouple the contribution of the individual effects. It is found that the complete decoupling of the linear electro-gyration from the linear electro-optic effect is not possible for this symmetry, while the inverse is feasible, and that the separation of the quadratic from the linear electro-optic effect can be achieved. For the linear phenomena, index ellipsoid geometries and eingenpolarizations are calculated, and analytic expressions are derived for the intensity of a light beam propagating through a crystal followed by a polarizer, thus providing valuable information for the design of devices and/or measurements of corresponding coefficients.