Non reflection and perfect reflection via Fano resonance in waveguides

Lucas Chesnel (1, 2) , Sergei A Nazarov (3, 4)

1 CMAP - Centre de Mathématiques Appliquées - Ecole Polytechnique
2 DeFI - Shape reconstruction and identification
3 Saint Petersburg State Technical University
4 IPME - Institute of Mechanical Engineering Problems [St. Petersburg]

We investigate a time-harmonic wave problem in a waveguide. By means of asymptotic analysis techniques, we justify the so-called Fano resonance phenomenon. More precisely, we show that the scattering matrix considered as a function of a geometrical parameter ε and of the frequency λ is in general not continuous at a point $(ε, λ) = (0,λ_0$) where trapped modes exist. In particular, we prove that for a given $ε = 0$ small, the scattering matrix exhibits a rapid change for frequencies varying in a neighbourhood of $λ_0$. We use this property to construct examples of waveguides such that the energy of an incident wave propagating through the structure is perfectly transmitted (non reflection) or perfectly reflected in monomode regime. We provide numerical results to illustrate our theorems.

Mots clés: Waveguides; Fano resonance; non reflection; perfect reflection; scattering matrix

Domaines: Equations aux dérivées partielles [math.AP]; Analyse numérique [math.NA]; Physique mathématique [math-ph]

Lucas Chesnel, Sergei A Nazarov. Non reflection and perfect reflection via Fano resonance in waveguides. Communications in Mathematical Sciences, 2018. ⟨hal-01694063⟩