LAUSR

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.