  In this article we discuss a model describing key features concerning the
lineshapes and the coherent absorption conditions in Fano-resonant dissipative
coupled oscillators. The model treats on the same footing the weak and strong
coupling regimes, and includes the critical coupling concept, which is of great
relevance in numerous applications; in addition, the role of asymmetry is
thoroughly analyzed. Due to the wide generality of the model, which can be
adapted to various frameworks like nanophotonics, plasmonics, and
optomechanics, we envisage that the analytical formulas presented here will be
crucial to effectively design devices and to interpret experimental results.
