Weak coupling, strong coupling, critical coupling and fano resonances: A unifying vision

The transversal concepts of weak, strong and critical coupling, and of Fano resonances, are analyzed within a unified framework which relies on a simple classical model of driven-dissipative coupled oscillators. A careful exploration of the system's parameter space has led to the emergence of certain intriguing phenomena, which we named lineshape inheritance, universal absorption lineshape, and strong critical coupling. These concepts may be of relevance when attempting to understand the response of a diversity of systems, especially in the fields of (quantum) light-matter coupling, and of solid-state nanophysics, where the basic scheme of multi-oscillator dissipative resonances is often encountered.