Optimized cut of LiTaO3 for resonator filters with improved performance

In resonator filters, it is often desirable to minimize propagation loss simultaneously at resonant and anti-resonant frequencies. Using this criterion, we found an optimal dependence of rotation angle on electrode thickness in wavelengths, in rotated YX cuts of LiTaO₃ with At grating. In particular, 48°YX cut was found to be optimal for resonator filters with thick Al electrodes, about 10% wavelength. With rotation angle set to be optimal for the specified electrode thickness, the lines of nonsymmetric orientations were located, along which propagation losses at resonant and anti-resonant frequencies do not exceed 0.003 dB/Λ, electromechanical coupling coefficient is higher than 8% and power flow angle does not exceed 5°.