Title :
The highly sensitive optical measurement of absolute SAW amplitudes for power flow analysis
Author :
Franke, Kurt ; Ross-Messemer, Martin ; Menck, Alexander ; Hoeller, Frank Stefan ; Schmidt, Hagen ; Weilmacht, M.
Author_Institution :
Inst. fur Festkor per und Werkstofforschung, Dresden, Germany
Abstract :
The established optical method for the measurement of surface acoustic wave (SAW) amplitudes (simple probing) has been modified to result in the effective separation of scattered light from the SAW-diffracted light by means of two single mode optical fibers. In this way, the photodetector noise is drastically reduced, and absolute SAW amplitudes of 10/sup -12/ in can be detected easily. Using an additional precise measurement of the nondiffracted light by means of fiber shifting, the SAW amplitudes can be calibrated with an error of less than 3%. This method can be applied to deliver an accurate power flow analysis in SAW devices. As an example, for a YZ-LiNbO/sub 3/ transducer, the measured and calculated SAW power densities were found to agree within better than 6%.
Keywords :
acoustic variables measurement; acousto-optical effects; light diffraction; optical fibres; surface acoustic waves; LiNbO/sub 3/; SAW amplitude; YZ-LiNbO/sub 3/ transducer; calibration; light diffraction; light scattering; optical measurement; photodetector noise; power flow analysis; single-mode optical fiber; Acoustic measurements; Acoustic waves; Fluid flow measurement; Load flow analysis; Optical noise; Optical scattering; Optical sensors; Optical surface waves; Power measurement; Surface acoustic waves;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2003.1176527
