Effect of damping on magnetic induced resonances in cross waveguide structures
Résumé
We consider, in the frame of long-wavelength Heisenberg model, a simple magnetic device consisting of two dangling side stubs grafted at the same site along a waveguide. This simple structure is designed to obtain bound in continuum (BIC) modes, magnonic induced transparency (MIT) and magnonic induced absorption (MIA), the analogues of electromagnetic induced transparency (EIT) and absorption (EIA) resonances respectively. By detuning the lengths of the two stubs, a resonance can be squeezed between two transmission zeros induced by the two resonators. We give detailed analytical expressions for the transmission and reflection coefficients as well as the absorption coefficient of the whole structure. A sharp peak with high Q factor is found as the consequence of the constructive interference of the waves in the two stubs. For some specific detuning values, the Q factor may reach infinity giving rise to the so-called bound in continuum state. Also, we give several explicit expressions for other physical characteristics, e.g., the transmission function close to the resonance, the position, the width and the Fano parameters of the resonances as a function of the difference between the lengths of the stubs. The reported analytical results are obtained by means of a Green's function method. These results should have important consequences for designing a selecting or rejecting magnon filter.