Acousto-optical 2 × 2 switches of optical beams with different wavelengths for fibre-optic gyroscopes

New types of acousto-optical 2 × 2 switches of optical beams with different wavelengths, intended for fibre-optic gyroscopes, are analysed and proposed. These switches make it possible to transmit two different radiations through the same fibre coil and thus obtain two independent Sagnac signals related to coil rotation. A method for calculating the angular and frequency characteristics of the switches is described. Experiments on volume acousto-optical diffraction in a TeO₂ single crystal confirm, on the whole, the theoretical conclusions.