Acousto-Optic Devices with Phased-Array Transducers: Features of operation and applications

Peculiarities of anisotropic light diffraction in a periodically inhomogeneous acoustic field generated by a phased-array transducer with antiphase excitation of adjacent sections are studied theoretically. As opposed to the non-sectioned transducer, light diffraction in this case is practically absent when the optical wave falls on the phased-array cell at the Bragg angle. However, the diffraction can be observed at some other angles (called here as “optimal”), which are located on opposite sides from the Bragg angle. Our calculations have shown that, despite a significant acousto-optic phase mismatch, the diffraction efficiency can reach 100% at these optimal angles. This variant of acousto-optic interaction possesses a number of interesting regularities which can be useful for designing acousto-optic devices of a new type, in particular, acousto-optic modulators and deflectors intended for controllling of unpolarized optical radiation.