Multi-port acoustic beam splitter based on multi-level stimulated Raman adiabatic passage

The acoustic beam splitter, a critical device for partitioning incoming waves into multiple outgoing waves, has extensive applications in navigation, acoustic information processing and other fields. Leveraging the formal analogy between the Schrödinger equation of quantum mechanics and the coupled-mode theory of classical waves, we introduce the multi-level stimulated Raman adiabatic passage into the design of multi-port acoustic beam splitters. Due to the adiabatic property, three- or four-port acoustic waveguide splitters with low propagation loss are theoretically constructed, taking N = 4 as an example. By adjusting the spatial coupling structure between adjacent waveguides, beam splitting of the outgoing sound wave at any preferred intensity ratio can be achieved. Our numerical simulations are in good agreement with the theoretical predictions. This work closely relates the multi-level quantum adiabatic passage to the multi-port acoustic beam splitter, thereby expanding the categories and design concepts of acoustic beam splitters.