Patent US 4,159,539

A device for memorizing information by means of interactions between elastic waves and electromagnetic waves. It comprises a piezoelectric substrate, at least one electromechanical transducer receiving the information to be memorized, means for exciting a pulsating electric field through the substrate, said field interacting non-linearly with the elastic wave created by the transducer to form a spatial charge pattern representing said information and means for modifying the physical properties of the medium of propagation of the elastic waves in the region of said pattern, for memorizing. The reading is effected by a non-linear interaction between said pattern and the pulsating electric field.