Abstract
We have demonstrated and explored the effects of the hydrostatic pressure on a one-dimensional phononic crystal (1D PnC). In this regard, we designed the proposed 1D PnC structure with a stack of polycrystalline silicon (Si) and polymethyl methacrylate (PMMA) for four unit cells. A hydrostatic pressure (positive and negative) with values ranging from 0 to +/- 5 GPa is applied on the PnC design. By using the well-known transfer matrix method (TMM), we have investigated the transmittance spectrum of the proposed PnC where the mechanical characteristics of PMMA are discussed in the presence of the applied hydrostatic pressure. The obtained results exhibit the tunability of the phononic band gap (PnBG) by controlling the applied hydrostatic pressure in the considered ultrasonic region. We found that the PnBG width is decreased and shifted towards the higher frequencies as the hydrostatic pressure increases. The decrease in the width of the PnBG could be due to the increase in the velocity of sound and Young's modulus of PMMA layer with increasing the pressure. The tunability feature of the PnBGs under hydrostatic pressure can be useful in different acoustic applications such as switches, transducers, filters, sound suppression, and sensors.