Researchers at the University of Texas System have developed multimeter-wave acoustic resonators using thin-film piezoelectric materials such as lithium niobate / lithium tantalate or aluminum nitride / scandium aluminum nitride, in combination with intermediate buffer layers. These resonators support higher-order antisymmetric bulk acoustic modes (first and third antisymmetric tones), enabling operation at multimillion-Hz frequencies with improved performance.
High-frequency acoustic resonators are essential in RF filters, signal processing, wireless communication, and sensors. Traditional acoustic resonator designs often face trade-offs at millimeter-wave (mm-wave) frequencies: higher modes suffer from damping, energy loss, mode leakage, or reduced electromechanical coupling. Fabrication challenges also arise when achieving the required thinness, material quality, and ability to sustain higher-order modes. There is a need for devices that can reliably support multimode, high-frequency acoustic resonances with good efficiency and fabrication compatibility using state-of-the-art piezoelectric thin films.
This patent application discloses resonator devices in which a piezoelectric thin film (e.g., LiNbO₃/LiTaO₃ or AlN/ScAlN) is deposited on a substrate, with one or more intermediate layers (buffer layers, acoustic isolation layers) in the film stack to engineer mode confinement and reduce losses. The design harnesses higher-order antisymmetric bulk acoustic modes (not just fundamental mode) — specifically the first and third antisymmetric tones — to achieve resonant behavior at mm-wave frequencies. The intermediate layers help reduce acoustic leakage into the substrate and improve quality factors, enabling better performance at these high frequencies.
Supports mm-wave operation via higher-order acoustic modes (first and third antisymmetric).
Improved mode confinement and reduced acoustic losses due to intermediate layers.
Use of proven piezoelectric thin films (LiNbO₃/LiTaO₃ or AlN/ScAlN) allows compatibility with existing fabrication ecosystems.
Potential for higher quality factor (Q) at high frequency, which improves filter selectivity or sensor sensitivity.
Film-stack engineering allows tuning of resonance frequency, coupling, and suppression of undesired modes.
RF and mm-wave filters in wireless communication (5G/6G, satellite, radar).
High-frequency sensors (pressure, gas, acoustic) where mm-wave acoustic resonance is beneficial.
Signal processing components (frequency references, oscillators).
Integrated devices requiring compact, high-frequency resonant elements (e.g., in RF front-ends).
Potential use in quantum acoustic applications or microwave photonics where acoustic modes interact with electromagnetic or optical fields.
US 2025/0274279 A1 — Multimeter-wave acoustic resonators Multimeter-wave acoustic resonators (US20250062738A1) Google Patents