Collinear acoustico‐optic diffraction using a diffuse acoustic field

摘要

The acoustic waves propagating in a low‐loss crystal travel long distances after numerous reflections by the walls before vanishing and thus form a complex sound field in the crystal. From this sound field called ’’diffuse’’ it is possible to select different acoustic modes at given frequencies by means of flat and parallel, disposed normally to pure‐mode axes of the crystal, pairs of reflecting walls which form acoustic Fabry‐Perot interferometers. Some acoustic modes selected from the diffuse field are used for realizing collinear acousto‐optic diffraction and thus, it is shown that the overlapping in space of acoustic and light beams may be achieved in this way. A model for determining the intensities of the selected modes is established. The model is used for calculating the efficiency of the collinear diffraction.