Abstract: The design and prototype technology of a transducer with 180 MHz acoustic frequency are described for the experiment of Acousto-Optical Bragg diffraction in planar LiNbO₃ optical waveguide. The experimental phenomena are observed. When the input electric power reaches 80 mW, the diffraction frequency approaches 100%. This means that the diffraction power required by the superficial device is ten times smaller than that of the bulk device. The biffraction efficiency is largely dependent on the crystal quality. Although we did not make special design to enhance the bandwidth of the device, the Bragg diffraction could be observed when the acoustic frequency varies in the range of -40 MHz——150MHz.