Microwave Acoustics in Layered Structure.
Final technical rept. 20 Oct 73-30 Nov 75,
RENSSELAER POLYTECHNIC INST TROY N Y
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The initial objective of this research project was the characterization of the excitation and propagation of elastic waves in layered structures and the evaluation of the use of these structures in devices related to the field of microwave signal processing. A new side-entry laser probe technique was developed to accurately map the Rayleigh wave and the layer waves. This non-perturbing optical method gave direct information about the elastic field anywhere in the waveguide structure, the coupling efficiency between Rayleigh waves and layered waves and the nature of the elastic evanescent fields in the bounding solids. The high elasto-optic diffraction efficiency achieved utilizing this technique was employed to fabricate an elasto-optic modulator and convolver for signal processing. Studies on three basic convolver structures were made, though the emphasis in this contract was fabrication of 10 prototypes with center frequency 110 MHz. After these prototypes were completed, two other prototype convolvers using Si on LiNbO3 were built for operation at 230 MHz, 50 MHz bandwidth and 17 micro sec interaction time. The convolvers were tested and found to have good performance. Two new uses of the convolver structure were also found. These applications are ambiguity function generation and phase comparator in a phase locked loop.
- Line, Surface and Bulk Acoustic Wave Devices