Magnetically controlled bidirectional 2×2 elastic switch using Terfenol-D in a phononic crystal-based Mach-Zehnder interferometer

This study introduces a novel design for a bidirectional 2 × 2 elastic switch based on a Mach-Zehnder interferometer, which modulates input wave phases through the application of an external magnetic field, enabling precise control over the output wave paths. The magnetic switching mechanism utilizes two-dimensional solid-solid phononic crystals composed of a square lattice of tungsten cylinders embedded in a poly methyl methacrylate (PMMA) substrate. The Mach-Zehnder interferometer features two identical symmetrical arms filled with Terfenol-D cylinders, operating effectively within the MHz frequency range. Control of the switch is achieved by dynamically tuning Young's modulus of the Terfenol-D cylinders via the applied magnetic field. This modulation induces phase shifts in the elastic waves traveling through each arm, thereby directing the output based on the resulting phase difference. Finite element method simulations validate the design and demonstrate the switch's excellent performance, including an average extinction ratio of 15.14 dB and low insertion losses averaging 0.26 dB. The proposed elastic switch combines structural simplicity with strong functional potential, making it a promising candidate for applications in acoustic communication systems and networks.