Tunable Acoustic Lenses based on Phononic Crystals

A two-dimensional gradient-index phononic crystal (GRIN PnC) of steel cylinders in anethanol matrix was designed and simulated for ۶a at room temperature. The hyperbolicsecant profile of the refractive index is obtained by changing the scatterers radius of thestructure in the transverse direction to gradually refract the waves. The finite element methodis used to calculate the effective refractive index in each row of the structure and to investigatethe propagation of acoustic waves in the gradual medium. With the help of gradient structureequations, the analytical beam trajectories were obtained and compared with the wavepropagation results. The effect of temperature on the first band and thermal adjustment of thefocal point for ۰°C and ۵۰°C have been investigated. The obtained results show that it ispossible to shift the focal point at a certain frequency due to the changes of the effectiverefractive indices of the cylinders in the transverse positions for the calibration applications.

Keywords:

Phononic crystal lens , Hyperbolic secant profile , Thermal tuning , Focal point shift.