Nonreciprocal sound propagation via cascaded time modulated slab resonators
Résumé
In this work, we demonstrate nonreciprocal acoustic wave transmission in a two cascaded Fabry-Perot like slab resonators undergoing time modulation of their effective density. Phase difference is introduced in the time modulation between the two coupled resonators to produce spatial bias in order to access unidirectional wave propagation. A theoretical model based on plane wave expansion and transfer matrix method is developed to study the Fabry-Perot-based system. The theoretical model allows rapid and precise characterization of the acoustic dispersion, with results in excellent agreement with finite element based numerical simulations. We demonstrate acoustic nonreciprocity behavior for the fundamental acoustic mode, and further show that with proper optimization, the coupled Fabry-Perot based device can achieve nonreciprocal acoustic frequency conversion. This work could inspire designing simple and compact nonreciprocal acoustic devices for efficient wave control.
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