Acoustic Ridge Waveguide Technology
Abstract
The feasibility of etching single-crystal lithium niobate and alpha- quartz to produce wedge-shaped acoustic waveguides has been examined. The primary etchant considered was boiling hydrofluoric acid. Etch masks of sputtered chrome/gold were employed. Highly uniform small (approximately 0.001 inch high) waveguides could be produced in quartz substrates. LiNb03 waveguide fabrication was not possible due to the high defect density in the material. Spurious mode excitation problems were examined and found to be minimal in unapodized transducers on mechanically lapped waveguides with large transverse dimensions. Smaller transverse dimensions or apodization of the transducers introduced interfering modes. Apodization of interdigitated transducers on wedge waveguides was evaluated as a means of achieving bandpass shaping. The entire coupling range was found to be controlled by the first wavelength of apodization. Thus, impulse response weighting by apodization will require control of electrode geometry to within fractions of a wavelength from the apex of the waveguide.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1976
- Accession Number
- ADA029510
Entities
People
- Robert S. Wagers
Organizations
- Texas Instruments