In order to optimize the center frequency and bandwidth characteristics of the dual-piezoelectric-layer ultrasonic transducers, an investigation was conducted to find the optimal connection and material combination methods between piezoelectric layers for a dual-piezoelectric-layer structure utilizing systematic comparison and analysis. Finite element analysis (FEA) simulation results show that among all the connection methods, the one based on inversion layer technique exhibits the greatest performance. The simulation results also show that when a PMNT single crystal plate is used as the first piezoelectric layer and a PZT ceramic plate is used as the second piezoelectric layer with a thickness ratio of 7.5:2.5, the transducer presents about 16 % higher center frequency and 50 % broader −6 dB bandwidth as well as a shorter −6 dB lateral beam width compared with a conventional single-piezoelectric-layer transducer. The measurement results prove that the transducer with the proposed structure exhibits the greatest performance, which obtains about 42 % higher center frequency and 10.4 % broader −6 dB bandwidth compared with a conventional transducer. In the meanwhile, the proposed transducer has the shortest pulse length as well. These characteristics are conducive to improving the lateral and axial resolution of ultrasound imaging.

为了优化双压电层超声换能器的中心频率和带宽特性，通过系统的比较和分析，进行了调查，以找到双压电层结构的压电层之间的最佳连接和材料组合方法。有限元分析（FEA）仿真结果表明，在所有连接方法中，一种基于反型层技术的连接方法表现出最大的性能。仿真结果还表明，当将PMNT单晶板用作第一压电层，将PZT陶瓷板用作第二压电层时，其厚度比为7.5：2.5，与传统的单压电层换能器相比，该换能器具有更高的中心频率约16％，较宽的-6 dB带宽约50％，以及较小的-6 dB横向束宽。测量结果证明，具有所提出结构的换能器表现出最大的性能，与传统换能器相比，其中心频率提高了约42％，而-6 dB带宽提高了10.4％。同时，所提出的换能器也具有最短的脉冲长度。这些特征有利于提高超声成像的横向和轴向分辨率。与传统换能器相比，它的中心频率高约42％，带宽-6 dB宽10.4％。同时，所提出的换能器也具有最短的脉冲长度。这些特征有利于提高超声成像的横向和轴向分辨率。与传统换能器相比，它的中心频率高约42％，带宽-6 dB宽10.4％。同时，所提出的换能器也具有最短的脉冲长度。这些特征有利于提高超声成像的横向和轴向分辨率。