The highly sensitive optical measurement of absolute SAW amplitudes for power flow analysis.
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(-12) m 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-LiNbO3 transducer, the measured and calculated SAW power densities were found to agree within better than 6%.
Franke
Kurt
K
Institut fur Festkor per und Werkstofforschung, D-01069 Dresden, Germany. k.franke@ifw-dresden.de
Ross-Messemer
Martin
M
Menck
Alexander
A
Hoeller
Frank Stefan
FS
Schmidt
Hagen
H
Weihnacht
Manfred
M