A layered structure combining a thin plate of lithium niobate (LN) with a langasite (LGS) substrate was numerically investigated as an advanced substrate material for surface acoustic wave (SAW) devices with improved characteristics, including capability of operating at high temperatures. The longitudinal leaky SAWs (LLSAWs) propagating with negligible attenuation and high velocities up to 6400 m/s were found in LN/LGS using an optimization technique previously applied to the LN/quartz structure. Compared with quartz, the use of LGS as a substrate imposes less constrains on bonding at elevated temperatures for fabrication of a layered structure. Due to the specific acoustic anisotropy of LGS crystals, low-attenuated high-velocity waves exist in a wide range of LGS orientations, including the commercially available SAW cut, when LGS substrate is combined with an LN plate. In the found optimal structures, the electromechanical coupling increased from 5.5% to 14.5%, with increasing LN thickness, making LN/LGS substrate suitable for application in SAW devices with a widely varying bandwidth. In addition, low shear bulk wave velocities in LGS provide a wide spurious-free frequency range in resonators using LLSAW.

中文翻译：

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结合了LiNbO3和Langasite的SAW器件的高级基板材料。

数值研究了将铌酸锂（LN）薄板与硅酸铝（LGS）基板相结合的层状结构，作为用于表面声波（SAW）器件的先进基板材料，具有改善的特性，包括在高温下工作的能力。使用先前应用于LN /石英结构的优化技术，在LN / LGS中发现了纵向漏泄声表面波（LLSAW），其衰减可忽略不计，并且高达6400 m / s的高速传播。与石英相比，使用LGS作为衬底对在高温下进行粘合以制造层状结构的约束较少。由于LGS晶体具有特定的声学各向异性，因此低衰减的高速波存在于LGS取向的各种范围内，包括市售的SAW切割，当LGS基板与LN板结合时。在找到的最佳结构中，随着LN厚度的增加，机电耦合从5.5％增加到14.5％，这使得LN / LGS基板适合用于带宽变化很大的SAW器件。另外，LGS中的低剪切体波速度在使用LLSAW的谐振器中提供了宽的无杂散频率范围。