Resonant acoustic transmission through compound subwavelength hole arrays: the role of phase resonances

We study the resonant acoustic transmission through compound subwavelength periodic hole arrays. Fabry-Perot resonance peak splitting is found. We can attribute the phenomenon to phase resonances via calculating the phase difference between adjacent holes in a unit cell. Furthermore, by analyzing the transmission characteristics of different kinds of compound hole arrays for normal and non-normal incidence, it can be demonstrated that the phase resonances arise from the coupling between holes in a unit cell. In addition, we also discuss the transmission resonance originating from acoustic surface modes and illustrate the hybridized features of acoustic surface modes and Fabry-Perot modes. The results are expected to have advantages in tailoring resonant acoustic transmission properties.