Cascade acousto-optic frequency shift of light

A new method for drastically shifting the carrier frequency of light based on the acousto-optic (AO) cascade diffraction effect is described and investigated. The method is based on the peculiarities of anisotropic diffraction in anisotropic media and allows separation of the different diffracted beams in the multi-stage diffraction process. The feasibility of the novel method is experimentally verified by using a common TeO2 monocrystal as the AO medium and standard optical units. A prototype comprising a five-stage cascade process with a total frequency shift of 400 MHz was built and tested with an overall AO diffraction efficiency of 40%. Issues for improving this efficiency are discussed.