Inverse Design of an Ultrasparse Dissipated-Sound Metacage by Using a Genetic Algorithm

Acoustic metasurfaces have the potential to be a promising route for the development of compact sound -absorptive devices with ventilation capability. However, the dissipation mechanism of limited plane wave fronts and elaborate geometry configured by extensive parametric sweepings severely restricts the avail-able designs. Here, via establishing a cylindrical transfer matrix method combined with an inverse-design strategy of a genetic algorithm, we construct an optimized ultrasparse (with filling ratio of framework at 50%) dissipated-sound metacage (DSM), which theoretically (experimentally) demonstrates 99.1% (98.2%) absorptance for omnidirectionally radiated cylindrical sound at a prescribed frequency of 260 Hz in deep-subwavelength thickness. The perfect absorption is ascribed to the mode hybridization between two resonant meta-atoms in which one acts as a dissipated mode and the other as an acoustically soft boundary. Moreover, the balance between thickness and sparsity is investigated by demonstrating DSMs that show different filling ratios of air channels. We finally extend the paradigm into a broadband regime for exploring more potential practicability.