Non-reciprocal flexural wave propagation in a modulated metabeam

Flexural wave propagation in an Euler–Bernoulli beam coupled to a set of spring–mass resonators is investigated in the presence of a pump wave in the form of a space–time modulation of the beam-resonators coupling stiffness. A phase matching condition implies then that waves incident along or against the pump wave behave differently and gives rise in select frequency bands to one-way blocking and conversion of waves. In particular, one-way optical–acoustic transitions are proven possible and are quantified. Various orders of magnitude of relevant physical quantities, such as gap widths and interaction lengths, are estimated so as to guide future experimental implementations.