An integrable and configurable phononic beam splitter based on self-collimated surface acoustic waves

In this letter, self-collimated beam of surface acoustic waves (SAWs) based on phononic crystals (PnCs), made of cone-shaped micropillars attached on a half-space, are numerically demonstrated and utilized for device applications. The self-collimated SAW beam can be split by a geometric line defect in PnCs. Of special interest is that the energy ratio of self-collimated beams can be adjusted by varying the radius of the micropillars of the defect. As functional displays with scalability and integrability, a one-to-three beam splitter and a Mach–Zehnder interferometer of SAWs are designed by utilizing this mechanism, providing prospects for on-chip SAW sensing or signal filtering.