Spectrum-Clean LiNbO3/SiO2/SI SH-SA W Resonators Utilizing Combined Electrode Apodization and Propagation Angle Twisting

In this study, a high-performance spurious-free thin-film lithium niobate on insulator (LNOI) shear-horizontal surface acoustic wave (SH-SAW) resonator is developed using a combination of propagation angle twisting and crossed-interdigital transducers. By aligning the wave propagation directions to the zero-coupling orientations of the Rayleigh mode and applying electrode apodization, both Rayleigh and transverse spurious modes are effectively suppressed. The fabricated SH-SAW resonator, operating at 839 MHz, achieves a nearly spurious-free spectrum spanning 0.1 to 3 GHz, with an effective electromechanical coupling coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(k_{\mathrm{e}\mathrm{f}\mathrm{f}}^{2})$</tex> of 24.2%, a maximum Bode-Q factor of 552, and an admittance ratio (AR) of 68.8 dB, showing promising potential for applications in wideband radio frequency (RF) circuit.