Phononic Crystals: Physical Principles and Novel Structures

Phononic crystals (PnCs) are periodic materials that can control and manipulate the propagation of acoustic (or elastic) waves. The importance of paying attention to this area can be seen in applications such as wireless telecommunications, communication systems in shallow water, sensors, acoustic signal processing, and ultrasonic imaging. During the last two decades, various devices have been proposed, fabricated, and measured and a great amount of research has implemented topology optimization for designing these structural materials as well as the associated functional devices. In this study, a comprehensive overview of the state-of-the-art advances in governing principles of PnC operations are discussed, including the study of the background of PnCs, their types, and topologies, their applications in different fields, as well as their filtering and guiding properties. In this paper, we’ve reviewed two of our own work. First, a 1x2 multiplexer which is designed from two ring resonators and estimated Quality(Q) factor and frequency channel crosstalk at different temperatures(10<T<40℃) and pressures(0.1<P<5MPa). Second, an acoustic channel drop filter and evaluation of Q-factor with changes in parameters such as pressure, temperature, and molality (0.9<M<0.1 mol/Kg). In addition to our works, some of the other proposed simulated or fabricated structures are also presented. The relations and computational methods for solving the equations used in these structures are investigated which is the Finite Difference Time Domain (FDTD) method.