On the sound wave attenuation by spatiotemporally reconfigurable grating

Controllable wave propagation is impossible when the properties of a material or structure are fixed by fabrication. External actions are inevitable for adjusting material properties to change wave field characteristics in a desirable way. Another way to manage the wave field is to reconfigure the inner structure. This approach is exemplified in the paper by analyzing wave propagation through a space-time reconfigurable diffraction grating in air. The diffraction grating can be dynamically adjusted by moving it back and forth, creating a time-periodic change in its configuration. Instantaneous space-time reconfiguration represents the limit case for wave propagation control. It is demonstrated that in this limit scenario, complete sound isolation is achievable.