Surface Acoustic Wave Non-Linear Interactions in Lithium Niobate.

摘要

This report presents investigations of three types on non-linear surface acoustic wave (SAW) interactions in lithium niobate (LiNbO3). In all cases there are two waves interacting. In the first case, convolution, the waves are collinear and counter propagating. In the second case, collinear mixing, the waves are collinear and co-propagating. In the third case, non-collinear mixing, the waves are non-collinear and co-propagating. The theory for these interactions is presented first and is followed by experiments for each of the interactions. The convolver investigations are directed at understanding and quantifying the various losses and improving the efficiency for high frequency (800 MHz) operation. Convolvers were tested as high as 1 GHZ which is the highest frequency of operation ever reported for a SAW convolver. This establishes the potential for greater than 300 MHz instantaneous bandwidth. As a result the size, weight, and power savings are ten thousand times better than present digital technology. Investigations include propagation loss, diffraction, beam steering, attenuation, multimoding, output plate resistivity, and output matching. An upper practical limit seems to be 800 MHz. Efficiencies obtained at this frequency were within a few dB of those at 150 MHz. (Author)