Natural SPUDT behavior of YZ LiNbO3

The basic types of SPUDT cells include quite narrow fingers and gaps. However, SPUDT cell types longer than one wavelength and with fingers and gaps wider than a quarter wavelength generate rather big losses. The purpose of the present paper is to find low-loss NSPUDTs on YZ LiNbO₃. It is shown that the propagation directions +Z and -Z of crystals of crystal class 3m are not equivalent. But Al electrodes with a normalized thickness of some percents yield a quite small distance of transduction (TC) and reflection center (RC) which is irrelevant in practice. The problem is solved by using heavy metal electrodes like gold or platinum. In each case, we find three layer thickness values for which the TC-RC distance is λ/8. Furthermore, the influence of buried electrodes and dielectric layers on the NSPUDT behavior is studied. The NSPUDT effect of Au and Pt electrodes on YZ LiNbO₃ is confirmed experimentally.