Surface acoustic wave characteristics on zno/yz·linbo₃ structure and their application to elastic convolver

In an effort to improve the efficiency of an elastic convolver, we discussed ways to increase the electromechanical coupling factor of the LiNbO₃ (LN)substrate. We examined, both theoretically and experimentally, the surface acoustic wave (SAW) characteristics of ZnO films formed on the +Y·and -Y·planes of the YZ·LN substrates. As a result, it was clear that a larger electromechanical coupling factor, k_s, can be obtained with a ZnO film on the +Y·plane than on the -Y·plane of YZ·LN substrates. The maximum value of the coupling factor obtained was 0.32, which was 2.04 times the square (k_s²) of the value obtained without the ZnO film. By applying the LN substrate with the ZnO film on its +Y·plane to the elastic convolver, we obtained a processing time of 7.6°µs, a 3°dB bandwidth of 44°MHz and an efficiency of -58°dBm.