AI 中文总结
本文提出双晶周期极化钽酸锂平台，通过抑制电荷抵消实现高阶厚度剪切泛音激励，在室温及低温下获得高Q值（最高20507）和fQ乘积（最高1.98e13 Hz），为亚GHz和低GHz高Q可扩展微声学谐振器提供新方案。
AI 中文摘要
高品质因数（$Q$）和泛音工作模式使得在单个腔体内实现具有多个离散频率的窄线宽声学器件成为可能。然而，在更高阶模式下同时保持高$Q$值和足够的机电耦合仍然具有挑战性。在此，我们展示了一种双晶周期极化压电薄膜（P3F）钽酸锂（LN）平台，用于高阶厚度剪切（TS）泛音激励。该器件包含一个键合的80微米厚单晶X切LN双晶，具有相反极化方向，图案化的顶部电极和悬浮的底部电极，以及一个悬浮的空气腔。P3F配置减轻了高阶TS模式交替应力分布引起的电荷抵消，从而在广泛的泛音序列中实现了可测量的耦合。厚的LN声学腔和日益受限的高阶模式分布支持低损耗运行。测得的TS泛音延伸至1.75 GHz。在室温下，0.77 GHz和0.89 GHz的代表性泛音表现出11,338和11,917的3-dB $Q$值，对应的$fQ$乘积分别为$8.74\ imes10^{12}$和$1.06\ imes10^{13}$ Hz。从297 K冷却至12 K系统地增强了$Q$，在779 MHz处产生峰值3-dB $Q$为20,507，在1.379 GHz处达到最大$fQ$乘积$1.98\ imes10^{13}$ Hz。这些结果确立了双晶P3F LN作为亚GHz和低GHz范围内高$Q$、频率可扩展微声学谐振器的有前景平台。
英文摘要
High quality factor ($Q$) and overtone operation enable narrow-linewidth acoustic devices with multiple discrete frequencies in a single cavity. Maintaining both high $Q$ and sufficient electromechanical coupling at higher mode orders remains challenging. Here, we demonstrate a bimorph periodically poled piezoelectric film (P3F) lithium niobate (LN) platform for high-order thickness-shear (TS) overtone excitation. The device comprises a bonded 80-$μ$m-thick single-crystal X-cut LN bimorph with opposite polarizations, patterned top and floating bottom electrodes, and a suspended air cavity. The P3F configuration mitigates charge cancellation from the alternating stress distribution of higher-order TS modes, enabling measurable coupling across a broad sequence of overtones. The thick LN acoustic cavity and increasingly confined high-order mode profiles support low-loss operation. Measured TS overtones extend to 1.75 GHz. At room temperature, representative overtones at 0.77 and 0.89 GHz exhibit 3-dB $Q$ values of 11,338 and 11,917, corresponding to $fQ$ products of $8.74\times10^{12}$ and $1.06\times10^{13}$ Hz, respectively. Cooling from 297 to 12 K systematically enhances $Q$, yielding a peak 3-dB $Q$ of 20,507 at 779 MHz and a maximum $fQ$ product of $1.98\times10^{13}$ Hz at 1.379 GHz. These results establish bimorph P3F LN as a promising platform for high-$Q$, frequency-scalable micro-acoustic resonators in the sub-GHz and low-GHz regimes.
