Resonant tunneling and bound states in the continuum

Many research topics these days involve the study of resonances in different structured media, especially in the field of optics. The seemingly different discovery of cyclotron resonance in metals by Mark Azbel and Emanuil Kaner in 1956, that opened a new way to study the Fermi surface of metals, has never been linked to optics. However, some later works of Mark Azbel on resonant tunneling are closely related to the concepts currently developing in optics and photonics, and here I discuss some of those fundamental ideas underpinned by the physics of Fano resonances and bound states in the continuum with a few examples of their experimental demonstrations.