基于声学超晶格铌酸锂的新型体声波器件

设计了一种集成的声学器件。它的基本结构是由下列3部分组成的，即换能器部分、声学开关部分和声传播介质部分，但其材料均来源于铌酸锂晶体。其中换能器与声开关部分是由声学超晶格铌酸锂构成的，而声的传播介质则是单畴铌酸锂。着重研究了声开关部分所外加的直流偏压对在该器件中传播的声波的影响。结果显示：声开关部分对声波的反射率受到这一外加偏压大小的影响，外加偏压越大，则反射率越强；声子带隙也受到外加偏压的影响，外加偏压越大，则声子带隙将会增宽。同时我们还发现了声开关的反射谱分布决定于铌酸锂超晶格的周期大小，且超晶格周期数的减小也会增宽声子带隙。该器件在设计上有两大优点：一是实现了声学开关器件的集成化，二是充分利用了声学超晶格铌酸锂最大的机电耦合系数。

An Acoustic Bulk-wave Device Made of Acoustic Superlattice LiNbO3

An integrated acoustic device, including a transducer, an acoustic switch and a transmission medium, is proposed. The first two parts are made up of acoustic superlattice LiNbO 3 (ASLLN). The influence of the DC bias on the propagation of acoustic waves in the switch part is investigated. The results show that the greater the amplitude of DC bias, the greater the reflectivity. The distribution of the reflection spectra depends on the thickness of domains. The acoustic band gaps broaden with the increase of the DC bias or with the decrease of the number of periods. The design of the device has such advantages that monolithic integration can be realized with the largest electromechanical coefficient of the excited modes of ASLLN being used.