Parity-time symmetric acoustic system constructed by piezoelectric composite plates with active external circuits

Researches on parity-time (PT) symmetry in acoustic field can provide an efficient platform for controlling the travelling acoustic waves with balanced loss and gain. Here, we report a feasible design of PT-symmetric system constructed by piezoelectric composite plates with two different active external circuits. By judiciously adjusting the resistances and inductances in the external circuits, we obtain the exceptional point due to the spontaneous breaking of PT symmetry at the desired frequencies and can observe the unidirectional invisibility. Moreover, the system can be at PT exact phase or broken phase at the same frequency in the same structure by merely adjusting the external circuits, which represents the active control that makes the acoustic manipulation more convenient. Our study may provide a feasible way for manipulating acoustic waves and inspire the application of piezoelectric composite materials in acoustic structures.

Automated summary

In this study, a feasible design of PT-symmetric system constructed by piezoelectric composite plates with two different active external circuits is reported. By adjusting the resistances and inductances in the external circuits, exceptional points can be obtained at desired frequencies to achieve unidirectional invisibility. The system can be at PT exact phase or broken phase at the same frequency in the same structure by adjusting the external circuits, representing convenient active control for acoustic manipulation.