| 摘要 |
PURPOSE:To improve the coupling coefficient and to eliminate spurious wave produced by an Rayleigh wave by providing a lithium niobate rotating Y plate as a piezoelectric substrate and a thin film with high density having a slower sound velocity than that of the rotating Y plate and using a pseudo elastic surface wave of the rotating Y plate as a Love wave type of elastic surface wave. CONSTITUTION:The substrate is constituted by the LiNbO3 rotating Y plate 11, a high density thin metallic film or dielectric thin film 12 having a slower sound velocity than that of the Y plate 11 formed on the rotating Y plate 11 so as to constitute a waveguide path, and interdigital electrodes 13, 14 exciting or receiving the pseudo elastic surface wave. The pseudo elastic surface wave excited by the interdigital electrode 13 or 14 is propagated onto the thin film waveguide path 12 as a Love wave. The relation among the coupling coefficient of the Love wave 21, of the Rayleigh wave 22 and a cut angle theta of the LiNbO3 rotating Y plate is shown in figure, in which no Rayleigh wave being a spurious wave is excited at 30-60 deg. of the theta and the coupling coefficient of the Love wave is 28-14%. |
