A compact hybrid structure of silica taper-assisted dual micro-bubbles is proposed and fabricated for broadband ultrasound sensing. UV-cured adhesive is dripped on silica taper to form dual elliptic microbubbles at preselected position. Scattering and reflected light in each microbubble converges at the two focal points of the ellipse to form two new point light sources, enhancing the emergence of high-order modes with strong multi-mode interference. The second microbubble with multi-mode interference further enhances the modulated light propagating from the first microbubble, realizing high contrast transmission spectrum. By exciting high-order harmonics of piezoelectric transducer (PZT) center at 3.7 MHz as ultrasound source, broad bandwidth acoustic signal from 3 kHz to 23.5 MHz is detected, owing to this hybrid structure with strong multi-mode interference along with polymer microbubbles with small Young’s modulus and small sizes. This unique dual-microbubble device makes attractive features for biomedical application and nondestructive test inspection.

中文翻译：

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用于超声传感器的锥形辅助双微泡装置

提出并制造了一种紧凑的二氧化硅锥形辅助双微泡混合结构，用于宽带超声传感。UV固化胶滴在硅胶锥上，在预先选定的位置形成双椭圆形微泡。每个微泡中的散射和反射光会聚在椭圆的两个焦点处，形成两个新的点光源，增强了具有强多模干涉的高阶模的出现。具有多模干涉的第二个微泡进一步增强了从第一个微泡传播的调制光，实现了高对比度透射光谱。通过激发以3.7 MHz为中心的压电换能器（PZT）的高次谐波作为超声源，检测3 kHz至23.5 MHz的宽带宽声学信号，由于这种具有强多模干扰的混合结构以及具有小杨氏模量和小尺寸的聚合物微泡。这种独特的双微泡装置为生物医学应用和无损检测提供了极具吸引力的功能。