Natural SPUDT behavior of YZ LiNbO3 for reflective delay lines

The goal is to develop low-loss reflective delay lines based on surface acoustic waves (SAW) for 2.45 GHz which are insensitive to fluctuations of technological parameters. We want to use natural SPUDTs (NSPUDT) to reduce the loss of devices. Because of technological stability the propagation direction should be a pure-mode direction. The cuts of LiNbO₃ with Euler angles (0o, ψ, 90°) are candidates for NSPUDT directions. At the same time, the propagation direction is a pure-mode direction independently of ψ. YZ LiNbO₃ is the best known cut of this type. Three layer thickness values with NSPUDT behavior are found when platinum electrodes are used. The experimental NSPUDT effect in vicinity of 2.45 GHz is demonstrated. An IDT including Pt electrodes is applied for a reflective delay line design on YZ LiNbO₃. All the reflectors are made of Al. This configuration is based on the calculation of reflection and transmission coefficients by means of a Finite Elements Method The width of finger electrodes amounts to 0.30. Moreover, some ψ values for complete NSPUDT behavior using Al electrodes have been found theoretically.