Tuning of Fano resonances by rotation of continuum: Wave faucet

Sadreev, Almas F.; Pilipchuk, Artem S.; Lyapina, Alina A. EPL, 117 (5): Doi: 10.1209/0295-5075/117/50011 MAR 2017

We consider wave transmission in a non-axisymmetric waveguide which consists of cylindrical resonator and two semi-infinite cylindrical waveguides whose axes are shifted relative to each other by azimuthal angle Δphgr. Although rotation by Δphgr does not change the eigenfrequency spectrum of the resonator, it effectively tunes the Fano resonances and respectively gives rise to an analog of a faucet opening and closing wave flux under rotation. Moreover, under the rotation of the waveguide and variation of the length of resonator, numerous events of the Fano resonance collapse occur to argue for the bound states in the continuum. In the nearest vicinity of the bound states scattering wave function with orbital angular momentum shows phase dislocations with giant vortical acoustic flows around.