Bound states in the continuum (BICs) provide a viable way of achieving high-Q resonances both photonics and acoustics. In this work, we propose general method constructing Friedrich-Wintgen (FW) BICs accidental coupled acoustic waveguide-resonator system. We demonstrate that FW can be achieved with arbitrary two degenerate closed resonator, regardless whether they have same or opposite parity. ...

This letter presents an eighth-order dual-mode waveguide filter, fabricated using the selective laser melting (SLM) technique. The filter employs four dimpled ellipsoid resonators, operating at fundamental TM101 mode. During printing, can be mechanically self-supported without any internal supports. Compared to filters employing tuning posts, proposed is less sensitive fabrication er...