Surface acoustic wave channel waveguides by AlN films

[object Object] Surface acoustic wave (SAW) channel waveguides have been fabricated by sputtering deposition of AlN films on YX- and XY-LiNbO3 substrates. Since the SAW phase velocity is higher in AlN than in the substrate, the supported film acts as a cladding for the guide, while the unmodified substrate corresponds to the core. Both single channel and two-channel waveguides in the configuration of an acoustic coupler have been investigated. Measurement of the acoustic field in the guiding structures has been done by use of acoustooptic probing techniques. The guiding properties of the guides have been probed at different distances from the transducer. In the case of two-channel waveguides the coupling length for the fundamental mode has been measured for different guide separation distanc