PS-2 High Coupling and High Temperature Stable Surface Acoustic Wave Substrates Using Groove Type Interdigital Transducers

In this paper, in order to obtain the new substrates with the higher coupling of electromechanical coefficients (k²) and near zero temperature coefficients of frequency (TCF), the thin periodic grooves and interdigital transducers are fabricated on the high coupling substrates. The results showed high k² over 0.4 at H/lambda, = 0.15 for rotated Y-cut, X-propagating LiNbO₃ leaky SAW substrates, and high k² over 0.08 and small TCF of -10ppm/degC at H/lambda = 0.1 and zero TCF at H/lambda = 0.3, for 36deg Y-X LiTaO₃ leaky SAW substrates. The groove type substrates are applied to resonator and nondispersive filters using dispersive unidirectional transducers. The experimental results of k² and reflectivities using grating groove resonators and UDT filters showed the good agreements to the theoretical ones