Abstract
In this work, a quality factor(Q)enhancement technique has been investigated for the fundamental shear-horizonta(SH0)mode lithium niobate resonators. Four supporting tether designs are employed in combination with an optimized release distance to enhance the acoustic isolation and consequently attain a higher Q without introducing spurious modes. The fabricated prototype resonator with tapered tether design at 90 MHz exhibits a Q of 2,600 and an electromechanical coupling(k-{t}^{2})of 17%, resulting in a high figure-of-merit(FoM=k-{t}^{2}times Q)of 442. The Q of 2,600 underlines a 2X Q enhancement from a conventional straight supporting design. The perfectly matched layer(PML)method is adopted to optimize the energy loss with different acoustic boundaries. Results from our comprehensive finite-element analyses(FEA)are also reported to rationalize our design choices and confirm a Q estimation error within 15%
of the measured values.